TRANSACTIONS. Vol.II, Part Editor - J. W. HESLOP HARRISON, D.Sc., F.R.S. King's College, Newcastle upon Tyne.

Transcription

1 TRANSACTIONS Vol.II, Part Editor - J. W. HESLOP HARRISON, D.Sc., F.R.S. King's College, Newcastle upon Tyne. CONTENTS PAGE The Magnesian Limestone Area of Durham and its Vegetation. By J. W. Heslop- 1 Harrison, D.Sc., F.R.S., and J. A. Richardson, MSc The Genus Rubus in Northumberland and Dnduun. By Yolande Heslop-Hanison 29 A Long Pollen Diagram from Northumberland. By Katbleen B. Blackburn 40 On the Occurrence of the "Upper Forest layer" around Cold Fell, N. Pennines. By 44 Job. Precbt Price: Five Shillings and Sixpence. Post Free. Printed by T. & G. Allan (Newcastle) Ltd., Westaate Road.

2 THE MAGNESIAN LIMESTONE AREA OF DURHAM AND ITS VEGETATION J. W. HESLOP HARRISON, D.Sc., F.R.S. AND J. A. RICHARDSON, M.Sc. I. INTRODUCTORY Although records of flowering plants from the Magnesian Limestone areas of Durham exist in Stephen Robson's "British Flora" (1777), it was not until the last two decades of the eighteenth century that the flora of these districts was subjected to intensive study. During that period, Winch, Thornhill and Waugh began the investigations which resulted in the production of their "Botanists' Guide through the Counties of Northumberland and Durham". This classical publication, considering the early date (1805), and the state of communications at the time, was a remarkable piece of work for, in addition to other notable plants, it lists a considerable percentage of the calcicole plants on record for East Durham. However, researches in the vegetation of the latter district did not cease with this book. In 1838, Winch was in a position to publish his famous "Flora of Northumberland and Durham" in Volume II of the Transactions of the Natural History Society of Northumberland, Durham and Newcastle upon Tyne in which there was set out an adequate account of the vegetation flourishing on the Magnesian Limestone. Soon after this work appeared, in 1846, the Tyneside Naturalists' Field Club came into being. This was a vigorous body which took its title seriously and organized field meetings to investigate those parts of the two counties noteworthy from the botanical standpoint. Amongst such areas, in the first ten years of its existence, the club visited the Magnesian Limestone outcrops on no fewer than ten occasions. This work continued until 1868 when Baker and Tate's "New Flora of Northumberland and Durham" was produced in Volume II of the Natural History Trans- actions of Northumberland and Durham. This work served to emphasize the thoroughness with which the early workers had investigated the plants of the east Durham calcareous soils. Subsequently, the Natural History Society and the Tyneside Naturalists' Field Club continued these researches until 1924 when the Northern Naturalists' Union, in conjunction with the former body, began to assist in the work. It is a significant fact that its very first field meeting (July 5th, 1924) was planned to examine Hawthorn Dene and cliffs as far south as the Foxhole Dene. Moreover, over a considerable number of years, many similar excursions have been made by the Union to Magnesian Limestone localities, as well as others carried out by keen individual workers. 1

3 Recently, Lousley (1950), dealing with our Magnesian Limestone tracts, asserted that, unfortunately, the only recent papers available were a few short notes in the Vasculum, but this is not the case, for in 1939, one of us (J.W.H.H.) in collaboration with Mr. G. W. Temperley brought together all the plant records for the area in a "Flora of the Three Northern Counties". During the past four years we have been re-examining the ground to extend and confirm the observations of the early workers. The tloristic results of these labours are set out below. II. A GENERAL CONSIDERATION OF THE AREA Magnesian Limestone, as its name sufficiently indicates, is a limestone containing magnesium carbonate. But, whilst the rock is definitely of dolomitic tendencies, it must not be supposed that the ratio between the quantities of calcium carbonate and magnesium carbonate present remains constant. As a matter of fact, in specimens originating in Durham the amounts of the latter compound they contain may tluctuate between 0 and 44.9 per cent. Moreover, its structure and outward appearance display a range of variation such as is exhibited but rarely by any other British rocks. For instance, it may appear as a compact limestone, as a small-grained crystalline dolomite like that found in Castle Eden Dene, near the Blackhall Rocks and elsewhere on the coast, as irregular earthy masses amongst more stony rocks, as a limestone with a laminated structure such as is prevalent in the quarries near Sunderland and at Marsden, as a pseudo-brecciated rock occurring at Frenchman's Bay and so on. In Durham the Magnesian Limestone formation occupies a roughly triangular area of 230 square miles, bounded in the east by the cliffs on the coast between South Shields and Hartlepool. To the west, as it traverses the Coal Measures, its limits are clearly defined by a broken line of eminences, of varying heights, indented by numerous irregular "bays" produced by denudation. These hills are seen at their best at Cleadon, West Boldon, Penshaw Hill, Sherburn Hill, Strawberry Hill, Old Cassop, Quarrington Hill, Coxhoe, Merrington, Westerton, Eldon, Midderidge, East and West Thickley, Redworth, Killerby, Headlam and the White Cross. South of this, the Magnesian Limestone leaves the county to pass into Yorkshire. Although the escarpment never attains really great elevations, it displays considerable changes in level as it proceeds southwestward. Thus, from South Shields to West Boldon, it varies from heights less than 100 feet to 300 feet; thence it runs on to Thrislington and shows elevations up to 550 feet. Continuing southward, it reaches 644 feet at Westerton, 540 feet at Eldon, 400 feet at East Thickley and then its maximum of 650 feet just west of Redworth. At Pierce Bridge where it crosses the Tees into Yorkshire it falls to a height of 231 feet. 2

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5 The third side, or base line of the triangle, is greatly obscured by drift, but it curves from West Hartlepool past Wynyard Park, Grindon and Stillington to strike the Tees south of Darlington. East of the escarpment, the Magnesian Limestone breaks into a series of low undulating hills relieved at intervals by less broken stretches. Toward the coast line, these are intersected by a number of deep denes or ravines of various lengths. Sixty years ago these were veritable beauty spots. Through each, great and small alike, flowed its own crystal- clear stream. In the more confined and narrower ones these ran along the base of steep slopes clad with almost impenetrable thickets of mixed vegetation. In some of the more important denes, like Castle Eden Dene, the burns, in their upper reaches were walled between precipitous cliffs supporting an abundance of rare flowering plants and ferns. Lower down, the denes merged into broader valleys with their slopes covered with the mixed ash woods characteristic of the Magnesian Limestone. However, the advent of the railway rudely disturbed these wood-land solitudes, and the destruction then commenced was speeded up by the sinking of three modern collieries at Easington, Horden and the Blackhall Rocks. Almost immediately, on the stretch of coast between Easington and the Coastguard Station, no fewer tban four of the dene most productive of botanical and entomological rarities were over-whelmed on the landward ends by debris from the mines. To complete the catastrophe, in the richest of these, the coal refuse caught fire, with the result that the dene was smothered by dense clouds of noxious fumes. Further, the cuttings and the embankments necessitated by the construction of the new Easington- West Hartlepool road, carried the work of destruction farther inland to destroy additional stretches of the larger denes, to obliterate some of the smaller ones entirely and to initiate movements destined to destroy utterly the seaward portion of Crimdon Dene. In spite of the widespread devastation outlined above, the more picturesque parts of Castle Eden Dene, the whole of Hawthorn Dene and much of Hesleden Dene remain in a more or less satisfactory con- dition. Their vegetation still provides a source of pleasure to the enthusiastic botanist. In addition, with the extinguishing of the burning pit debris and the cessation of promiscuous tipping, many of the minor denes show encouraging signs of recovery. The latter possibility, with the probable taking over of Castle Eden Dene by the Nature Conservancy, fills us with renewed hopes that future naturalists will be enabled to write, not of the "Doom of the Denes" as Wm. Carter was constrained to do in 1924, but of their rehabilitation. 4

6 Finally, along the coast there stretches a long line of Magnesian Limestone cliffs providing diverse habitats, which, in spite of repeated firing, still maintain their peculiar florulae, described amongst others, below. III. THE FLORULAE OF SPECIAL HABITATS Taking the Magnesian Limestone tract as a whole, owing to the soft and friable nature of the rock, it has produced soils, which, in spite of their comparatively unproductive nature, have been under cultivation for a very long period. Thus the actual areas in which the vegetation remains in a reasonably undisturbed condition, and therefore available for study, are quite small. In fact, in addition to those listed in the previous section, very few are left except certain stations on the escarpment too rough for cultivation, small woodlands, bank sides, rough pastures, limited zones around quarries and, paradoxically enough, the quarries themselves. Rough Pastures Of the rough pastures remammg, we have examined a long series situated at Cleadon, Houghton, Pittington, Elemore, Strawberry Hill, Hawthorn, Easington, Cassop Vale, Black Hall Rocks, Old Quarrington, East Hetton and Raisby and elsewhere. Whilst the floras in these stations conform to the same general pattern, they are not uniform. One, in the vicinity of Cassop Vale, has a composition which gives a good average idea of the rest, and is now listed :- Ranunculus bulbosus Senecio erucifolius Heliathemum nummularium S. Jacobaea Viola hirta Carlina vulgaris V. Riviniana Carduus nutans V. Reichenbachiana C. crispus Polygala vulgaris Centaurea nigra Linum catharticum C. Scabiosa Ononis repens Crepis virens Anthyllis Vulneraria Leontodon hispidus Lotus corniculatus L. autumnalis Fragaria vesca Hieracium Pilosella Alchemilla xanthochlora Campanula rotundifolia Agrimonia Eupatoria Primula veris Poterium Sanguisorba Centaurium umbellatum Sanguisorba officinalis Gentiana Amarella Pimpinella Saxifraga Veronica Chamaedrys Conopodium majus Rhinanthus stenophyllus Silaum silaus Euphrasia nemorosa var. collina Galium verum Origanum vulgare Knautia arvensis Thymus Serpyllum Succisa pratensis Stachys Betonica Scabiosa Columbaria Plantago maritima Bellis perennis P.lanceolata Antennaria dioica P. media Achillea Millefolium Listera ovata 5

7 Dactylorchis Fuchsii ssp. dunelmensis Helictatrichon pubescens Orchis mascula H. pratense Gymnadenia conopsea Arrhenatherum elatius Coeloglossum viride Sesleria caerulea Luzula campestris Koeleria gracilis L. pilosa Dactylis glornerata Carex caryophyllea Briza media C. flacca Festuca ovina Anthoxanthum odoratum Brachypodium sylvaticum HoIcus lanatus Selaginella selaginoides Trisetum flavescens In rough pastures elsewhere, additional plants appear. Thus, at Garmondsway, Bromus erectus becomes locally dominant with the equally rare Cirsium eriophorum forming a significant member of the community. With these are to be noted Hypericum pulchrum, Agrimonia odorata, Chenopodium vulgare, Bromus sterilis and Anacamptis pyramidalis. No great distance away near Highland House, Bromus ereetus is also plentiful, although A. pyramidalis is distinctly scarce. A novelty there, however, is Arabis hirsuta, only known elsewhere on the Magnesian Limestone at Moorsley. At Old Quarrington, Astragalus danieus, usually a coast plant with us, flourishes whilst near Easington we have observed Hypericum montanum, Genista tinetoria, Campanula glomerata, Serratula tinetoria and Ophrys apifera in similar habitats. Scrub In many cases these pastures give rise to scrub associations varying locally in composition. These we have examined at Cleadon, West Boldon, Pittington, Cassop, Quarrington, Old Quarrington, Kelloe, Garrnondsway, Raisby, Highland House, Hawthorn, and the Blackhall Rocks. Where we have been able to study the development of these associations the first invader of the grassland appears to be the ash. In some cases, however, when ash fails, hawthorn seems to have played the part of poineer. At Garmondsway, where the development of the scrub has been recent, the shrubs include Crataegus monogyna, R. canina (agg.) R. dumetorum (agg.), R. dumalis (agg.), R. obtusifolia (agg.), R. mollis, Prunus spinosa (rare), Rubus spp. and Viburnum Opulus. Whilst the ground vegetation is composed of:- Polygala vulgaris Agrimonia Eupatoria Viola hirta Heracleum Sphondylium V. Riviniana Galium verum Hypericum puichrum Knautia arvensis Linum catharticum Succisa pratensis Lotus corniculatus Senecio Jacobaea Lathyrus pratensis Carduus nutans Vicia Cracca Cirsium vulgare Fragaria vesca C. arvense Potentilla reptans Centaurea nigra Poterium Sanguisorba C. Scabiosa 6

8 Hieracium Pilosella Holcus lanatus Primula veris Sesleria caerulea Plantago Ianceolata Dactylis glomerata Centaurium umbellatum Briza media Clinopodium vulgare Festuca avina Prunella vulgaris F. rubra Rumex Acetosella Bromus erectus Trisetum f1avescens B. sterilis Arrhenatherum elatius Brachypodium sylvaticum Of other scrublands that occurring about half a mile from Old Quarrington is of special interest, for it breaks into three distinct sections. In the most easterly of these, although odd hawthorns and Rosa spinosissima are present, the dominant shrub is Ulex europaeus. Here the ground flora consists of plants substantially the same as those listed for the rough pastures near Cassop Vale. On the other hand, the scrub in the west is predominantly of the hawthorn type relieved here and there by rose and bramble species. In this area, the general vegetation consists of an impoverished version of that characteristic of the eastern section. In all probability, this fact depends upon recent ploughing and regeneration. In the central portion, where there are obvious signs of ancient quarrying operations, damper and more sheltered conditions prevail. There the shrubs are reinforced by Fraxinus excelsior, Viburnum Opulus, Corylus Avellana and Salix Caprea, with Hedera Helix, Lonicera Periclymenum and Tamus communis as climbers. In the open and moister areas, in addition to many of the plants more at home in the drier eastern stretch, may be found an abundance of Primula farinosa and Pinguicula vulgaris whilst the denser part, which might be treated equally well as woodland, supports in its ground layer Ranunculus Ficaria, Viola Riviniana, V. Reichenbachiana, Melandrium rubrum, Oxalis Acetosella, Geum urbanum, Fragaria vesca, Asperula odorata, Veronica officinalis, Sanicula europea, Orchis mascula, Allium ursinum, Arum maculatum, Carex sylvatica, Brachypodium sylvaticum and other commoner grasses. In other localities, additional shrubs are encountered. Thus the scrub near Raisby includes Viburnum Lantana, and that at Hawthorn, Euonymus europaeus and Calluna vulgaris, the former two plants being very rare with us. Turning now to the coast denes, we find that the more extensive ones, like those at Castle Eden and Hawthorn, support beautiful mixed woodlands whilst those of narrow and shallower types are occupied by dense scrub, more especially on slopes facing south. One of these, situated south of the Blackhall Rocks, and near the Lime Kiln Gill, contains :- Shrubs Ulex europaeus R. dumetorum Rosa rnollis R. canina (agg.) 7

9 R. coriifolia (agg.) Rubus spp. R. spinosissima Sambucus nigra Prunus spinosa Viburnum Opulus Crataegus monogyna Ground Vegetation Ranunculus Ficaria Tussilago Farfara Viola Riviniana Senecio sylvaticus V. Reichenbachiana Cirsium lanceolatum V. canina Centaurea nigra Cerastium vulgatum C. Scabiosa Stellaria media Lapsana communis Hypericum puichrum Crepis virens Geranium molle Hieracium Pilosella G. Robertianum Hypochaeris radicata G. sanguineum (rare) Sonchus asper Trifolium repens Campanula rotundifolia T. pratense Primula veris Fragaria vesca Echium vulgare Potentilla sterilis Origanum vulgare P. reptans Prunella vulgaris Agrimonia Eupatoria Stachys officinalis Poterium Sanguisorba Teucrium Scorodonia Pimpinella Saxifraga Plantago lanceolata Angelica sylvestris Agrostis stolonifera Galium Aparine Brachypodium sylvaticum Eupatorium cannabinum Deschampsia caespitosa Solidago Virgaurea Dactylis glomerata Bellis perennis Pteridium aquilinum Achillea Millefolium On the opposite slope, the ground is much wetter, and the vegetation varies but little from that occurring in similar habitats elsewhere in Durham, although we have noted the presence of odd examples of Salix Caprea, S. atrocinerea and S. nigricans. It is dominated by coarse grasses like Dactylis glomerata although more interesting plants are present. In particular, attention should be directed to a strong colony of Primula vulgaris and its very variable hybrid with P. veris. This population affords a splendid opportunity for the study of Introgressive Hybridization. Unlike the position on the other side, relatively few examples of P. veris are to be noted. Also occurring abundantly is Dactylorchis Fuchsii which differs considerably in stature and vigor from forms observed elsewhere. As the dene approaches the sea, the shrubs vanish although a procumbent form of Juniperus communis appears. Moreover, many of the plants growing in the thickets are replaced by Helianthemum nummularium, Geranium sanguineum, Lotus corniculatus, Anthyllis Vulneraria, Ononis repens, Poterium Sanguisorba, Sanguisorba officinalis, Pimpinella Saxifraga, Daucus Carota, Succisa pratensis, Scabiosa Columbaria, Senecio erucifolius, Carlina vulgaris, Thymus Serpyllum, Prunella vulgaris and Plantago media. Still nearer the sea, Plantago maritima and Armeria 8

10 maritima abound with P. Coronopus in smaller numbers. North of the Blackhall Rocks lies the Blue Horse Gill, once noted for its characteristic scrub and its plant treasures generally. Thirty years ago, however, the vegetation was seriously damaged by acid fumes. As it is now displaying marked signs of recovery, some account of the present position seems desirable. On the northern slopes low, dense thickets of Ligustrum vulgare and Rosa pimpinellifolia flourish, interrupted by more open spaces supporting masses of Helianthemum nummularium, Geranium sanguineum, Salix repens and their usual associates. On the opposite slopes, S. repens and Ligustrum vu/gare still maintain themselves, but the dominant shrub is Salix nigricans, appearing in a low-growing guise. Amongst the more important members of the ground vegetation, in addition to species observed on the north banks, Melandrium rubrum, Primula farinosa, Parnassia palustris, Pyrola rotundifolia, Epipactis palustris, Dacty/orchis latifolia var. coccinea and D. Traunsteinei seem specially noteworthy. Forty years ago, to the west, where this gill broadened out some- what, the scrub merged into a small wood. In this woodland, the chief trees were oak and ash, the accompanying shrubs being Rosa canina (agg.), R. dumetorum (agg.), R. coriifolia (agg.), Sambucus nigra, Viburnum Opulus, Lonicera Periclymenum, Corylus A vellana, Salix Caprea and S. nigricans. Similarly, the ground flora bore a close resemblance to that usually found in Durham oak-ash woods, although curiously enough, intruders like Helianthemum nummularium, Viola hirta and Brachypodium sylvaticum occurred freely in drier open places. Due to colliery developments and road-making operations this woodland vanished soon after the first war. Still further north, there once existed a long series of similar gills like Ash Gill and Whiteside Gill. These also supported vegetation essentially the same as that growing in Cold Cream Valley and the Blue Horse Gill, although, necessarily, there were local variations in composition. They, too, exhibited woodland conditions as they receded from the sea. In all of these miniature woodlands Fraxinus excelsior was the dominant tree. Woodlands A consideration of the woodlands in these tiny gills brings us to an examination of the major woods in the area. Owing to the extent of cultivation on the Magnesian Limestone, and the unsuitable nature of many of the soils, very few natural woodlands exist, and, of these, those growing on drift or boulder clay, are not characteristic. More suitable for our purpose are those clothing the larger denes exemplified by Castle Eden Dene, Crimdon Dene, Hesleden Dene, Hawthorn Dene, Easington (Horden) Dene and Ryhope Dene. Since it is more easily dealt with, 9

11 and seems typical of the others, we propose to choose Hawthorn Dene for our purpose, our investigations in Castle Eden Dene being reserved for a further communication. Hawthorn Dene lies roughly a mile-and-a-half south of Seaham Harbour, and, from its mouth at Hawthorn Hive, it penetrates a similar distance inland. Its flora includes :- Trees and Shrubs Ilex Aquifoliurn Cornus sanguinea Euonymus europaeus Sambucus nigra Acer campestris Viburnum Opulus A. Pseudo-platanus (planted) Lonicera Periclymenum Ulex europaeus Fraxinus excelsior Prunus insititia Ligustrum vulgare Rubus spp. Viscum album Rosa spinosissima Ulmus montana R. canina (agg.) Betula pendula (rare) R. durnetorum (agg.) Corylus Avellana R. coriifolia (agg.) Quercus petraea (rare) R. mollis Fagus sylvatica (planted) R. Sherardi (agg.) Salix Caprea Crataegus monogyna S. atrocinerea Hedera Helix Taxus baccata Ground Vegetation In considering this type of vegetation, it should be remembered that its composition varies according to the amount of boulder clay present, the openness of the habitat, its proximity to Hawthorn Burn and so on. List :- Anemone nemorosa Rubus Idaeus Caltha palustris R. caesius Aquilegia vulgaris (formerly) Geum urbanum Helianthemum nummularium G. rivale Viola hirta Fragaria vesca V. Riviniana Agrimonia odorata V. Reichenbachiana Poterium Sanguisorba Polygala vulgaris Sanguisorba officinalis Melandrium rubrum Chrysosplenium oppositifolium Hypericum dubium Epilobium hirsutum H. hurnifusum E. parviflorum H. pulchrum E. montanum H. montanum E. palustre Linum catharticum Chamoenerion angustifolium Geranium sanguineum Circaea lutetiana G. sylvaticum Sanicula europaea G. pratense Conopodium majus G. robertianum Angelica sylvestris Oxalis Acetosella Heracleum Sphondylium Genista tinctoria Galium cruciatum Vicia Cracca G. Aparine Lathyrus pratensis Asperula odorata Filipendula Ulmaria Valeriana officinalis 10

12 Scabiosa Columbaria Parietaria diffusa Erigeron acris Neottia nidus-avis Achillea Millefolium Listera ovata Senecio erucifolius Cephalanthera longifolia Carlina vulgaris Orchis mascula Carduus tenuiflorus Dactylorchis purpurella C. nutans D. Fuchsii Serratula tinctoria Ophrys apifera Centaurea nigra O. insectifera C. Scabiosa Gymnadenia conopsea Picris hieracioides Coeloglossum viride P. echioides Allium ursinum Lactuca muralis Convallaria majalis Campanula glomerata Lilium Martagon C. latifolia Paris quadrifolia C. rotuodifolia Luzula campestris Primula vulgaris Arum maculatum P. veris Paris quadrifolia Lysimachia vulgaris Tamus communis L. nemorum Agrostis stolonifera Centaurium umbellatum Deschampsia caespitosa Gentiana campestris Holcus mollis G. Amarella Helictotrichon pubescens Myosotis scorpioides Arrhenatherum elatius Solanum Dulcamara Melica uniflora Veronica montana Briza media V. officinalis Dactylis glomerata Euphrasia nemorosa Festuca ovina Rhinanthus stenophyllus F. rubra Thymus Serpyllum (agg.) F. gigantea Origanum vulgare Brachypodium sylvaticum Glechoma hederacea Pteridium aquilinum Prunella vulgaris Phyllites Scolopendrium Stachys officinalis Athyrium filix-femina S. sylvatica Dryopteris filix-mas Teucrium Scorodonia D.dilatata Ajuga reptans Equisetum Telmateia Viscum album E. sylvaticum As will be recognized, the flora of Hawthorn Dene, although not so striking as that of Castle Eden Dene, is still very rich, and to emphasize this we supply a florula of a wood, near Quarrington Hill, immediately adjoining exposures of Magnesian Limestone and thin limestone soils. In this wood the principal tree is ash, although odd crab apples, hollies, birches, mountain ashes and sycamores are present, with a shrub layer composed of hawthorn, elder, guelder rose, hazel and sallow. The ground vegetation is extremely poor :- Anemone nemorosa Oxalis Acetosella Ranunculus auricomus Geranium robertianum R. Ficaria Geum rivale Viola Reichenbachiana G. urbanum V. Riviniana Fragaria vesca Melandrium rubrum Potentilla Fragiastrum 11

13 Rubus Idaeus Sanicula europaea Conopodium majus Angelica sylvestris Hedera Helix Galium Aparine Asperula odorata Crepis paludosa Veronica montana Stachys sylvatica Urtica dioica Orchis mascula Allium ursinum Tamus communis Scilla non-scripta Arum maculatum Athyrium Filix-femina Dryopteris Filix-mas Within the edges of this ashwood, and extending beyond them, there is a considerable amount of marshy ground which supports an interesting assemblage of plants, some of which are extremely local in Mid and East Durham. These are :- Caltha palustris Cirsium palustre Trollius europaea C. heterophyllurn Filipendula Ulmaria Primula farinosa Geum rivale Scrophularia aquatica Epilobium hirsutum Mentha aquatica Galium palustre Phalaris arundinacea Valeriana dioica Phragrnitis communis v. officinalis Sea banks, dunes and cliffs Between Marsden and the old rifle range at Hart, there stretches, with occasional breaks, a long range of Magnesian Limestone cliffs which, near Hart, give place to low, ill-developed sand dunes, yielding, on the landward side, to steep grassy slopes. At the mouth of Crimdon Dene, the dunes are interrupted although south of that, they continue to Hartlepool. In many places, the cliffs are crowned by a succession of dry banks and dampish hollows. Sometimes, when the boulder clay has crumbled away and slipped downward, the banks may run down almost to the sea. Under such circumstances, as, for instance, just north of the Blackhall Rocks, the lower portions may display a tendency to dune formation. On dry slopes, the vegetation bears a close resemblance to that listed for Cassop Vale pastures and for the seaward declivities of Cold Cream Valley. However, especially near the Blackhall Rocks, Haw- thorn Hive and Easington Colliery, that vegetation may be varied by the local occurrence of dense thickets of Ligustrum vulgare, and abundance of Salix repens, a sprinkling of Salix nigricans, occasional Juniperus communis with Geranium sanguineum, Astragalus danieus, A. glyciphyl/os, Agrimonia odorata, Serratula tinetoria, Cirsium heterophyllum, Origanum vulgare, Primula veris and even, near the sea, Thalictrum arenarium. In addition, at Easington, in its only Durham station, Hypochaeris maeulata may be observed. Worthy of note, too, is the complete absence of Sesleria caerulea. 12

14 Sometimes almost imperceptibly and sometimes abruptly, the plants of the banks give place to a vastly different assemblage in the depressions. When a shrub does grow there, the plant represented is the subalpine Salix nigricans, which owing to wind action, is often dwarfed and flattened. Competing with it are such plants as Angelica sylvestris, Valerina offici- nalis, Eupatorium cannabinum, Mentha aquatica, Iris Pseudacorus, Juncus spp., Phragmitis communis and Equisetum Telmateia. On thinner soils more important species replace these. Of such plants Primula farinosa, Pinguicula vulgaris, Samolus Valerandi, Centaurium Iittorale, Parnassia palustris, Pyrola rotundifolia, Valeriana dioica, Pulicaria dysenterica, Dactylorchis Traunsteineri, D. latifolia, Epipactis palustris and Carex vulpina are the most interesting. One unusual fact should be 'recorded here and that is the presence of Cal/una vulgaris in one of the hollows. Often, when either bank or hollow is fired, recovery may be postponed indefinitely, and we have a strong invasion of such coarse vegetation as bracken and cock's foot grass. Turning now to the dunes, we find that near Hart they are dominated by Ammophila arenaria, intermingled in more sheltered places with masses of Rosa spinosissima. Other plants observed there included Thalictrum arenarium, Geranium sanguineum, Erodium cicutarium, Lotus corniculatus, Rosa mollis, Poterium Sanguisorba, Campanula rotundifolia, Hypochaeris radicata, Crepis virens, Plantago media, Carex arenaria, Desmazeria loliacea and Agropyronjunceum. At the Crimdon Dene end on an isolated section of the dune there used to grow an enormous thicket of wild roses, composed of such Durham rarities as Rosa micrantha and R. rubieinosa with various forms of R. canina and R. dumetorum. Apart from the vegetation of the cliff hollows and slopes, very few plants grow on the cliffs themselves, only Matricaria maritima, Armeria maritima and Asplenium marinum demanding special note. The sea spleenwort still grows sparingly from the mouth of Hawthorn Dene to the Blackhall Rocks. Limestone Quarries Because of the value of Magnesian Limestone for building, blast furnace and other purposes, the mineral has been quarried for a very long period. Generally, the quarries have been situated on the edge of the escarpment although many occur at suitable points elsewhere. In any case, in the past, whenever quarrying operations were suspended, the abandoned quarries were left open, and thus afforded sheltered refugia for hordes of invading plants. Necessarily, such plants were those fitted for life upon limestone rocks, or upon thin limestone soils. In general, the colonists have managed to maintain themselves, and to increase greatly in numbers. As a consequence, there now exist in 13

15 many old quarries magnificent populations available for study. As was inevitable, such colonies vary in facies from quarry to quarry. We have therefore, determined to describe the vegetation of Haswell Quarry as being fairly typical of all. This consists of:- Polygala vulgaris Centaurea nigra Silene Cucubalus Hieracium Pilosella Cerastium vulgatum Hypochoeris radicata C. arvense Taraxacum vulgare Hypericum perforatum Sonchus oleraceus H. humifusum S. asper H. pulchrum Campanula rotundifolia Linum catharticum Primula veris Acer Pseudo-platanus Fraxinus excelsior Ulex europaeus Centaurium umbellatum Trifolium pratense Gentiana campestris T. repens G. Arnarella T. procumbens Digitalis purpurea Anthyllis Vulneraria Veronica officinalis Lotus comiculatus V. Chamaedrys Vicia Cracca Euphrasia nernorosa V. sepium Rhinanthus stenophyllus Lathyrus pratensis Thymus Serpyllum Rubus fruticosus (agg.) Plantago maritima Fragaria vesca P. lanceolata Potentilla reptans P. media Poterium Sanguisorba P. major Rosa canina (agg.) Rumex obtusifolius R. dumetorurn (agg.) R. crispus R. obtusifolia R. Acetosa R. dumalis Betula pendula R. coriifolia Salix viminalis Crataegus monogyna S. atrocinerea Epilobium montanum Dactylorchis purpurella Heracleum Sphondylium D. Fuchsii Sambucus nigra D. Fuchsii x D. purpurella Galium verum Gymnadenia conopsea Knautia arvensis Coeloglossum viride Scabiosa Columbaria Carex Goodenowii Bellis perennis C. caryophyllea Erigeron acris Agrostis stolonifera Achillea MilIefolium Deschampsia flexuosa Achillea Ptarmica Arrhenatherum elatius Chrysanthemum Leucanthemum Sesleria caerulea Senecio vulgaris Dactylis glomerata S. squalidus Briza media S. erucifolius Poa annua S. Jacobaea Agropyron repens Carlina vulgaris Dryopteris Filix-rnas Cnicus Ianceolatus Equisetum arvense C. arvensis Whilst no attempt is made to list completely the whole of the plants growing in every quarry, we mention the most interesting of the plants 14

16 occurring in the quarries named below: AYCLIFFE: Clematis Vitalba, Viola odorata, Hypericum hirsutum, Sorbus intermedia, Daucus Carota, Scabiosa Columbaria, Viburnum Opulus, Ballota nigra, Chenopodium rubrum, Asparagus officinalis, Typha latifolia, T. angustifolia, Eriophorum angustifolium, Zannichellia gibberosa. BISHOP MIDDLEHAM: Helianthemum nummularium, Sagina nodosa, Hypericum dubium, H. quadrangulum, H. montanum, Ononis repens, Astragalus danicus, Crepis taraxacifolia, Centaurea Scabiosa, Stachys arvensis, Acinos arvensis, Salix pentandra, S. Caprea, S. atrocinerea, S. purpurea, S. phylicifolia, Anacamptis pyramidalis, Festuca gigantea. CATLEY: Helianthemum nummularium, Bromus erectus. FERRYHILL: Cerastium tomentosum, Eupatorium cannabinum, Dactylorchis latijolia var. pulchella. FULWELL: Carduus nutans, Polygonum Hydropiper, Senecio squalidus, Ophrys apifera. GARMONDSWAY: Cirsium eriophorum, Carduus nutans, Viburnum Opulus, Anacamptis pyramidalis, Bromus erectus. HAWTHORN: Genista tinctoria, Orchis mascula, Viola tricolor. HIGHLAND: Arabis hirsuta, Helianthemum nummularium, Anacamptis pyramidalis, Bromus erectus. RAISBY: Sagina apetala, Geranium dissectum, Cotoneaster Simmonsii, Campamula Rapunculoides, Echium vulgare, Carduus nutans, C. crispus, Salix nigricans, Asplenium Ruta-muraria, Phyllitis Scolopendrium. TROW: Teucrium Chamaedrys, Anacamptis pyramidalis, Ophrys apifera. WINGATE: Viola odorata, Sagina nodosa, Valeriana officinalis, Petroselinum crispum, Crepis mollis, Bartsia serotina, Salix nigricans, Dactylorchis praetermissa, Orchis mascu/a, Botrychium Lunaria, Ophioglossum vulgare, Phyllitis Scolopendrium. [For the past four years, one of us (J. A. R.) has been studying the physiological and ecological problems connected with the colonization of the immature soils of these quarries and others elsewhere. The results will be presented in a later publication.] IV. A LIST OF THE MORE NOTEWORTHY PLANTS In the following list only such plants as are restricted to the Magnesian Limestone, or for any other reason seem worthy of detailed treatment, are singled out for special mention. In the case of the genus Rosa it should be noted that only very recent observations are included. For earlier records of wild roses in Northumberland and Durham, either on or off the Magnesian Limestone, the pages of the Vasculum should be consulted. Clematis Vitalba L.-Near the old windmill at Aycliffe, 15

17 Trollius europaeus L.-In a wood in Cassop Vale, on marshy ground adjoining it and near Bishop Middleham; also very abundant in the marshes at Billingham where the soil is heavily charged with Magnesian Limestone. Helleborus viridis L.-Probably not native, but occurring at Shotton and South Hylton. Aquilegia vulgaris L.-In Castle Eden, Hawthorn and other Magnesian Limestone Denes. Berberis vulgaris L.-Rare in the scrub near KeIloe. Arabis hirsuta (L.) Scop.-Common in a rough pasture at Moorsley, and on limestone rocks near Highland House. Reseda stricta Pers.-Almost certainly an introduction, but found on the hillside at Pittington. Helianthemum nummularium L.-Quite general on the Magnesian Limestone on banksides, cliff tops, roadsides, rough pastures, open denes and elsewhere, but thinning out southward so that at Aycliffe it is totally absent. Plants with pale lemon-coloured flowers, blotched with orange in the centre, grow in the little dene just north of the Blackhall Rocks. Viola odorata L.-In many of the denes, and in great masses at Aycliffe and Old Wingate. V. hirta L.-Common on sea banks, hillsides and similar places; the variety variegata Gregs, is to be found in Cassop Vale, and white forms at Wheatley Hill. V. calcarea (Bab.) Gregs.-So Far only detected at Strawberry Hill, Pittington Bishop Middleham and Quarrington Hill. V. Reichenbachiana Bor.-Common in Cassop Vale, Quarrington Hill, Coxboe- Seaham Harbour, Hawthorn Dene, Elemore, Pittington and near the Tees. Dianthus deltoides L.-In a small dene near Bishop Middleham, growing with Anacamptis pyramidalis. Cerastium arvense L.-Scattered on bare places on the Magnesian Limestone; not common. C. arvense L. x C. vulgatum L.-This hybrid grows on the Wear near Butterby and in Lambton Park. Hypericum hirsutum L.-Plentiful in all the denes and in old quarries. H. montanum L.-In Hawthorn and Castle Eden Denes and also at Bishop Middleham; also on the railway banks near Easington Colliery. Linum anglicum Mill.-Rare and irregularly distributed; Penshaw Hill, Tunstall Hill, Marsden and Kelloe. L. catharticum L.-Very abundant, and one of the first colonists when limestone soils are disturbed. Malva rotundifolia L.-Not frequent now; only detected at Old Wingate and Cleadon. Acer campestre L.-Tn all the bigger denes, and often plentiful in hedges on the south-east edge of the Limestone. Geranium columbinum L.-Occasional in the area as at Cleadon. G. sanguineum L.-Very common on sea-banks along the Durham Coast and at the seaward end of Castle Eden Dene. Euonymus europaeus L. -Not rare in Ryhope, Ha wthorn, Castle Eden and Hesleden Denes. Ononis repens L.-Not rare on cliff hollows, banksides and in old quarries; plants with white flowers were noted near Bishop Middlsham O. spinosa L.-With the preceding and a little more plentiful inland. 16

18 O. spinosa L.-With the preceding and a little more plentiful inland. Anthyllis Vulneraria L.-Much more frequent on the Magnesian Limestone than elsewhere in Durham. Trifolium striatum L.-Not seen by us, but reported from Whitburn, Cleadon, etc. T. filiforme L.-Rediscovered at Pittington by us, but recorded over a hundred years ago from Fulwell, Cleadon, Whitburn and Castle Eden. Astragalus danicus Retz.-Very sporadically along the coast from Marsden to Crimdon Cut; observed inland at Quarrington Hill and Bishop Middleham. A. glycyphyllos L.-Only seen on the cliff tops between the Foxholes and Hawthorn Dene. Vicia angustifolia L.-The variety Bobarti Forst., grows on banks above Cassop Vale. Filipendula hexapetala Gilib.-Reported years ago from Byers Quarry near Whitburn and from Coniscliffe. Agrimonia odorata (Gouan) Mill.-In quantities on the South slopes of Castle Eden and Hawthorn Denes near their mouths as well as at Sea ham and Hart. Poterium Sanguisorba L.-Abundant everywhere in the area, and also one of the earliest colonists when Magnesian Limestone soils are disturbed. Rosa arvensis Huds.-A rapidly vanishing species; only known now from Aycliffe and Shincliffe. R. spinosissima L.-Plentiful along the coast, but inland at Quarrington Hill, Pittington, Penshaw Hill, Aycliffe and elsewhere. R. rubella Sm.-This alleged species, found by Winch on the Durham coast, and by one of us (J. W. H. H.) at Hart, is nothing but the F 2 generation of hybrids between R. spinosissima and members of the ViIlosae group as one of us (J. W. H. H.) has proved by experimental breeding. R. canina L.-Very common everywhere; var. lutetiana Lem. at Pittington Hawthorn, Aycliffe and Highland House; var. sphaerica (Gren.) Dum. at Kelloe and Old Wingate ; var. flexibilis (Déségl.) Rouy at Hawthorn and Haswell; var. senticosa (Ach.) Baker at Kelloe; var. oxyphylla (Rip.) W.-Dod at Haswell and Aycliffe; var. mucronulata (Déségl.) W.-Dod at Kelloe and Highland House; var. rhynchocarpa (Rip.) Rouy at Haswell, Bishop Middleham and Aycliffe; var. globularis (Franch.) Dum. at Highland House and Aycliffe ; var. Carioti (Chab.) Rouy at Aycliffe; var. recognita Rouy at Aycliffe; var. sylvularum (Rip.) Rouy at Pittington, Highland House and Aycliffe, R. dumetorum Thuill.-Widespread but rarer than R. canina; var. urbica (Lem.) W.-Dod at Aycliffe, Blackhalls and Crimdon Dene; var. semiglabra (Rip.) W.-Dod at Aycliffe, Highland House, Bishop Middleham and Pittington ; var. ramealis (Pug.) W.-Dod at Pittington; var. calophylla Rouy non Chr. at Old Wingate and Kelloe ; var. platyphylla (Rau) W.-Dod at Aycliffe ; var. spinetorum at Aycliffe. R. dumalis Becbstein (= R. glauca auct. Angl.)-Scattered bere and there, and rarer than the next species; var. Reuteri at Raisby, Old Wingate, Coxhoe and Kelloe; var. glaucophylla Winch at Easington, Haswell, Raisby, Coxhoe and Kelloe; var. jurassica Rouy at Kelloe; var. subcanina Christ at Kelloe and Coxhoe. R. caesia Sm.-Var. frutetorum (Bess.) H.-Harrison at Pittington; var. implexa (Gren.) H.- Harrison at Hawthorn; var. Walsoni (Baker) H.-Harrison at Pittington ; var. Bakeri (Déségl.) H.-Harrison at Old Wingate ; var. cryptopoda (Baker) H.-Harrison at Haswell; var. Linloni (Scheutz) H.-Harrison at Pittington and Old Wingate. 17

19 R. obtusiflora Desv.-This species, formerly supposed to be rare in, or absent from, Co. Durham, has been found to occur everywhere on the Magnesian Limestone and elsewhere: var.tomentella (Lem.) Baker at Haswell, Bishop Middleham and Highland House; var. Borreri Woods at Aycliffe ; var. sclerophylla (Scheutz) W.-Dod generally distributed; var. glandulosa Crep, near Highland House. R. mollis Sm.-Abundant on the coast, and at Coxhoe, Pittington, Moorsley- Quarrington Hill, Raisby, Cassop Vale, Deneholm, etc.; var. relicta H.-Harrison at Quarrington Hill; var. glandulasa generally with the type; var. caerulea Woods at Aycliffe and Pittington. R. Sherardi Davies.-Thinly distributed; var. typica W.-Dod at Elemore- Pittington, Moorsley, Hawthorn, Crimdon Cut, Highland House, Cassop Vale, etc. ; var. submollis (Ley) W.-Dod at Hawthorn; var. suberecta (Ley) W.-Dod near Pittington; var. cinerascens (Dum.) W.-Dod between Elemore and Pittington. R. micrantha Sm.-Very rare and restricted to the Magnesian Limestone in Durham; known from the mouth of the Crimdon Beck, Cornforth and Easington Dene. R. mollis Srn. x R. spinosissima L.-Near Hawthorn Dene, South Hetton and Quarrington Hill. In the last station the mollis form involved is the white-flowered variety relicta. R. Sherardi Davies x R. spinosissima L.-On the edge of Hawthorn Dene and in Crimdon Cut. R. tomentosa Sm.-Very rare indeed in Durham; only found near Shincliffe. R. canina L. x R. spinosissima Sm.-In an old quarry on the roadside near Kelloe; the bush covers an area of 750 square feet. R. caesia Srn. x R. spinosissima L.-on the dump from the limestone quarry near the mouth of Hawthorn Dene. R. canina L. x R. obtusifolla Desv.-On the slopes of the hill near the quarry at Pittington. Parnassia palustris L.-Very common in the hollows on the coastal cliffs, and more sparingly in the denes. Petroselinum crispum Mill.-Fully naturalized on a limestone cliff at Old Wingate. Pimpinella major (L.) Huds.-Not common in the area between Sunderland and and Crimdon Dene. P. Saxifraga L.-Much commoner in grassy places on the Magnesian Limestone than elsewhere in Durham. Silaum Silaus (L.) Schinz & Thell.-As with the preceding species. Pastinaca sativa L.-Waste places, where it is sometimes abundant; a doubtful native. Daucus Carota L.-Not observed by us off the Magnesian Limestone, where it is often common on grassy slopes. Cornus sanguinea L.-Occasional in all the more extensive denes. Viburnum Lantana L.-Almost certainly wild near Raisby Quarries, and possibly so on Coxhoe Hill. Galium erectum Huds.-Very rare; only observed near Coxhoe and Witton- le-wear. Scabiosa Columbaria L.-Abundant everywhere on the Magnesian Limestone, but rarer in the southern portion. 18

20 Eupatorium cannabinum L.-Flourishes in immense beds in damp hollows south of Deneholm. The plant is dimorphic there, occurring in a form with pink flowers and red stems, and in another with white flowers and green stems; also at Ferryhill. Erigeron acris L.-Well distributed in the area and sometimes abundant as at Fulwell, Hawthorn, Haswell, Bishop Middleham, Wingate, Raisby; rarer in the south. Antennaria dioica (L.) Gaertn.-Very rare, but occurring locally in Cassop Vale and near Quarrington Hill. Senecio erucifolius L.-Generally of free occurrence, but diminishing toward the coast. S. squalidus L.-A recent introduction which has come to stay; found in many quarries. Carlina vulgaris L. -Not rare in waste and other bare places; extending its range to old clay pits and other disturbed areas. Carduus nutans L.-Not restricted to the Magnesian Limestone, but most plentiful there on waste ground. C. crispus L.- The same remarks apply to this species. C. nutans L. x C. crispus L.-Found occasionally where the parents occupy the same area. Cirsium eriopborum (L.) Scop.-Not recorded for Durham for over a hundred years, but discovered by us in abundance at Garmondsway in We have searched the old localities, Fulwell and Pittington, for which Winch reported the species in 1805, but we failed to find the plant. C. heterophyllum (L.) Hill.-Rare, but observed in the Foxholes Dene and in Cassop Vale, the most easterly stations now known for this thistle in Durham. Baker and Tate state that it used to occur in Castle Eden Dene. Serratula tinetoria L.-For this species Baker and Tate give localities from Marsden to Castle Eden Dene; it occurs in enormous quantities on the sea banks between Hawthorn Hive and Crimdon Cut. Moreover, it has greatly increased its numbers in recent years; also known from Shincliffe. Centaurea Scabiosa L.-Very common throughout the district on sunny banks, waste places, etc., but not so abundant as one approaches Aycliffe. A variety with white ray flowers and a purple centre was collected near Dawdon, and a white form not far from Highland House. Pieris hieraeioides L.-Very local; only observed in Hawthorn and Castle Eden Denes. P. echioides L.-Much more widely distributed than the preceding species; seen by us in many localities between Trow Quarry and Hesleden Dene. Crepis taraxacifolia Thuill.-In considerable numbers near Bishop Middleham, its first occurrence in the county. C. mollis Asch.-With us this species is western in its range; it was observed at Old Wingate, its lowest station, in C. paludosa (L.) Moench.-In all the Magnesian Limestone denes and also in the woods in Cassop Vale. Hypochaeris maculata L.-Very rare; on the cliffs south of Easington Dene. Lactuca virosa L.-On rocks along the Skerne at Ayc1iffe and in Castle Eden, Hawthorn and other denes. L. muralis (L.) Fressn.- Throughout the area and of freer occurrence than its congener. 19

21 Campanula Rapunculoides L.-In great abundance amongst debris and along the railway side near Raisby. Pyrola rotundifolia L.-Plentiful in one of the denes, and in two hollows on the sea banks, to the north of the Blackhall Rocks. Baker and Tate refer to its presence in Hawthorn, Castle Eden and Hesleden Denes, but we have not observed it in these localities. Primula veris L.-Abundant on the Limestone, where forms with lemon coloured flowers and leaves covered with a white felting on the lower side are quite common; these approach very near to P. Columnae Ten. On the sea banks between Easington and the mouth of Crimdon Dene hybrids with P. vulgaris Huds. are quite plentiful, and amongst such populations backcrosses and other generations later than the F2 lots are not rare. P. farinosa L.-Once well dispersed over the Magnesian Limestone; now limited, as far as our researches go, to colonies in cliff hollows near the Blackhalls, in Cassop Vale and on broken ground near Quarrington Hill. Samolus Valerandi L.-Found, not uncommonly, in barish, damp spots on sea banks and cliff tops between Ryhope and Crimdon Cut. Ligustrum vulgare L.-In all the denes but especially abundant on the sea-banks near Hawthorn and the Blackhalls; also still abundant in one of the smaller denes near tbe latter stations. Centaurium littorale (D. Turner) Gilmour.-On tbe sea-banks half a mile north of the mouth of Crimdon Dene and also near the Blackhall Rocks. Gentiana Amarella L.-Generally common on the Magnesian Limestone; plants with reddish-purple flowers form pure populations on Coxhoe Hill. G. campestris L.-Occupying the same area as the preceding, but much rarer. Litbospermum officinale L.-Stated by Baker and Tate to occur in Hylton, Hawthorn and Castle Eden Denes; to these stations we can add Crimdon Dene. Atropa Belladona L.-On a cliff ledge near Coniscliffe. Salvia verbenaea L.-Not observed by us, but recorded by Byker and Tate from Hawthorn Dene and Hartlepool. Origanum vulgare L.-Common in woods, hedges and on bank-sides. The flower colour varies enormously; thus, in Hawthorn Dene, every possible shade of colour between white and very deep rose-pink was noted. Clinopodium vulgare L.-Not rare in hedges and copses, also on the cliffs at the Blackhalls. Acinos arvensis (Lam.) Dandy.-A disappearing species; reported by Baker and Tate from various localities; only seen by us at Raisby and Bishop Middleham. Teucrium Cbamaedrys L.-Not seen in Durham since Winch's record made over J 50 years ago; collected by us on rocks in the Trow Quarry, South Shields. Plantago maritima L.-Common along the Durham Coast but occurring inland at Cleadon, West Boldon, Houghton-le-Spring, Moorsley, Sherburn Hill, Strawberry Hill, Haswell, Quarrington Hill and Garmondsway. P. media L.-Plentiful everywhere in grassy places on tbe Magnesian Limestone. Daplme Laureola L.-Sparingly in most of the denes. Viscum album L.-In Hawthorn Dene; possible introduced. Populus tremula L.-Very far from being so frequent as Baker and Tate assert; only noticed in Easington Dene in our area, where it grows a few yards from the sea. 20

22 SaIix pentandra L.-Many well-grown trees exist in an alder carr near Moorsley; also not rare near Bishop Middleham and Kelloe. S. purpurea L.-Seen only at Bishop Middleham. S. nigricans Sm.-Abundant and forming dense thickets on the sea-banks, and in the smaller denes between Easington and the Blackhall Rocks; also at Raisby, Old Wingate, and in Castle Eden Dene. S. nigricans Srn. x S. repens L.-On the sea-banks north of the Blackhall Rocks and near Easington. S. nigricans Srn. x S. Caprea L.-Near Deneholm on the coast. S. phylicifolia L.-Near Raisby and Bishop Middlesham; very unexpected stations. S. phylicifoiia L. x S. Caprea L.-In the latter locality. S. phylicifolia L. x S. repens L.-With the preceding; this is apparently the first English record of a very rare hybrid. S. cinerea L.- True S. cinerea occurs in Castle Eden and the Foxholes Dene ; S. atrocinerea Brot. prevails elsewhere. Neottia Nidus-avis (L.) L. C. Rich.-In Castle Eden and Hawthorn Denes. Cephalanthera longifolia (L.) Fritsch.-Rare in all the Magnesian Limestone denes. Epipactis palustris (L.) Crantz.-Plentiful in hollows on the sea-banks and in the smaller denes near the Blackhalls; also in Castle Eden Dene. Anacamptis pyramidalis (L.) L. C. Rich.-On sandy sea-banks at Marsden, in the Trow Quarry, at Easington Colliery and near the old rifle range at Hart; very abundant inland near Bishop Middleham, but rarer at Garmondsway and Highland House. A. pyramidalis L. C. Rich. x Gymnadenia conopsea (L.) R. Br.-A single example of this rare hybrid was obtained on the cliff top near Easington Colliery in Orchis Morio L.-Common in rough pastures between the railway and the sea- banks at the Blackhalls; also in meadows near Mainsforth. O. mascula L.-In the pastures just mentioned, in scrub near Hawthorn Dene, in hollows along the cliffs between Deneholm and Hart, in fields at Quarrington Hill and Mainsforth and generally in woods and denes; often in considerable numbers. O. Morio L. x O. mascula L.-In a mixed colony of the two species at the Black- hall Rocks. Dactylorehis latifolia L. sec. Pugsl.-In hollows along the sea-banks between Deneholm and the Blackhalls, chiefly in the form of var. coccinea Pugsley, although typical forms exist there; the var. pulchella Druce occurs not far from Ferryhill Station. D. latifoiia var. coccinea Pugsley x D. Fuchsii ssp. dunelmensis Heslop Harrison.- Sparingly in several of the marshy hollows on the sea banks north of the Blackhall Rocks. D. latifolia var. pulchella Druce x D. Fuchsii Druce.-Near Ferryhill Station. D. purpurella T. & T. A. Steph.-Locally abundant, with the var. pulchella Druce, throughout the area. D. purpurella T. & T. A. Steph. x D. Fuchsii Druce-Abundant in hybrid swarms wherever the two parents form a common colony. As the F 1 hybrids are fertile, back- crosses and later generations than the F 1 lot are encountered. D. purpurella T. & T. A. Steph. x Coeloglossum viride (L.) Hartm.-Several specimens near Ferryhill Station and Bishop Middleham. 21

23 D. purpurella T. & T. A. Steph. x Gymnadenia conopsea (L.) R. Br.-Odd examples near Bishop Middleham. D. traunsteineri (Saut.) Heslop Harrison.-Not rare in damp hollows between Deneholm and the Blackhalls. D. traunsteineri (Saut.) Heslop Harrison x D. Fuchsii ssp. dunelmemsis Heslop Harrison.- In at least three of the colonies of the first named species. D. Fuchsii Druce.-This species is abundant in most suitable places on the Magnesian Limestone, In the more inland localities it is more or less typical. On the other hand, on the coast, the ssp. dunelmensis prevails. This subspecies, described in the Vasculum for September, 1950, produces, amongst others, forms closlely resembling D. ericetorum E. F. Linton which were recorded as such in the Vasculum, XI, p. 121 (1925). Further, some examples strongly recall D. Fuchsii ssp. hebridensis (Wilm.) Heslop Harrison. In addition, individual colonies tend to show independent variation, more especial1y in respect to flower colour, some, like those at Fulwell, displaying a deep purple, and others, as at Quarrington Hill, etc., appearing almost white. O. Fuchsii Druce x Gymnadenia conopsea (L.) R. Br.-Several specimens in- volving typical O. Fuchsii were discovered near Bishop Middleham whilst odd specimens, on which the subspecies dunelmensis had participated, have been noted between Hawthorn Dene and the Blackhall Rocks. Ophrys apifera Huds.-In the Trow Quarry, South Shields, Fulwell, Easington, Old Wingate and Kelloe. O. insectifera L.-Formerly in all the major denes on the Magnesian Limestone. Gymnadenia conopsea (L.) R. Br.-Very abundant, especial1y on the coast and on railway banks; the form densifiora Wahl. is also of frequent occurrence. The plant, with us, is very variable in flower colour, which ranges from pure white to deep rose. Coeloglossum viride (L.) Hartm.-Wel1 distributed throughout the area and occasional1y very plentiful. Platanthera bifolia (L.) L. C. Rich.-In a heathery field, interspersed with gorse, south of the Blackhall Rocks. Cypripedium Calceolus L.-Once common in Castle Eden Dene but now extirpated. Tamus communis L.-Plentiful in thickets and hedges from Hylton to Hartlepool and Coxhoe. Allium scorodoprasum L.-In Hawthorn, Castle Eden and Hesleden Denes, also on the banks near Crimdon Cut. Asparagus officinalis L.-On a limestone cliff near Aycliffe; a garden escape. Conval1aria majalis L.-Only in Hawthorn, Castle Eden and Hesleden Denes. Lilium Martagon L.-Now naturalised in Hawthorn Dene. Paris quadrifolia L.-In most of the larger denes. Eriopborum angustifolium Honck.-In the quarry at Ayc\iffe. CaIamagrostis Epigejos (L.) Roth.-Rare in Castle Eden Dene. Sesleria caerulea (L.) Ard.-Abundant on the Magnesian Limestone from Marsden southward, but rare on the coast and disappearing at Aycliffe. Melica Dutans L.-In Castle Eden and Crimdon Denes. Bromos erectus Huds.-Found by the Rev. A. M. Norman at Sedgefield almost a hundred years ago; detected by us in 1951 at Garmondsway, Bishop Middleham, Highland House, Catley and Cassop Juniperus communis L.-Not common in the denes, but occurring also on the tops of the sea cliffs; now dying out. Taxas baccata L.-As fine well-grown old trees in Castle Eden Dene, rarer in Hawthorn Dene. 22

24 Asplenium marinum L.-On the sea cliffs from Marsden to the Blackhalls. Dryopteris aemula (Ait.) O. Kuntze.-On rocks near Quarrington Hill. Thelypteris Phegopteris (L.) Slosson.-In Castle Eden Dene. Gymnocarpium Dryopteris (L.) Newm.-As with the preceding. V. THE ORIGIN OF THE FLORA In any attempt to elucidate the origin of the flora and fauna of the Magnesian Limestone district of Durham we have one clear fact from which to commence our investigations; it is that during the closing stages of the Last Pleistocene Glaciation, the whole area was overridden by Cheviot ice. This circumstance makes it certain that, when the Ice Age ended, the plants and animals once existing there had been completely exterminated. However, with the disappearance of the ice, and the subsequent climatic amelioration, recolonization of the area became possible, and temperate and other biota pressed in from continental regions. Such migrations very obviously account for the bulk of that portion of our flora and fauna characteristic of temperate climates. Nevertheless, it must be emphasized that outbursts from refugia elsewhere contributed their quota of temperate forms as we shall proceed to demonstrate. In our opinion, in the past, in British phytogeographical studies too little weight has been attached to parallel work on the faunistic side; we refer, in particular, to researches on the distribution of the British Insecta. In this brief review, therefore, it is proposed to examine the position of a few of our insects, and to utilize the evidence yielded by their distributions in unravelling the history of our plants. One of the most interesting insects found on the Durham Magnesian Limestone is the Brown Argus butterfly, Aricia medon, of which the very distinct sub-species, A. medon ssp. artaxerxes is found in Scotland. Formerly, Durham examples of this species, irrespective of their facies, were known collectively as A. medon var. salmacis. In addition, all three forms have, at various times, been regarded as distinct species. Now, as one of us (J.W.H.H., Trans. Nat. Hist. Soc. Northumberland, Durham and Newcastle upon Tyne, N.S., VI, Part I, pp , 1924) has shown, it is recognised that Durham populations of A. medon consist of hybrid swarms brought into being by the interbreeding of the Scottish sub-species artaxerxes with typical southern English (or Continental) A. medon, intermingled with various proportions of segregates phenotypically resembling pure A. medon ssp. artaxerxes and typical A. medon. If this is warranted, the question as to how the interbreeding became possible must be propounded and answered. 23

25 In the original paper (l.e.), the view was put forward that, in all probability, the Scottish subspecies represented a perglacial survival, evolved in isolation in favoured refugia on our Atlantic fringes. We no longer regard this extreme position as defensible. In the present state of British biogeographical knowledge, we regard it as much more probable that ssp. artaxerxes is. a survival from the last Interglacial, or from one of Interstadial Phases of climatic improvement which interupted the Last Pleistocene Glaciation; as a matter of fact, we have adopted the hypothesis that it dates from the First Interstadial Phase. We picture that, when the glaciers waned finally, the newly released Scottish insect spread out from its western refugia to advance over ice- free land and meet in the Durham area similar contingents of typical A. medon pressing northward or northwestward. In the regions of contact and overlap the two sub-species interbred to produce, by Mendelian segregation and recombinations in F 2 and subsequent generations, the mixed and variable populations existing in present day Durham colonies. What is the bearing of this upon the problems of our flora? The larvae of the Brown Argus in all its forms feed upon the rockrose (Helianthemum nummularium). Hence, to account for the persistence of the species, whether from preglacial times, or from any of the other glacial stages mentioned, the plant must have flourished in the refugia postulated. Since the insect could not migrate without its food plant, it is obvious that, as the ice vanished, and the race artaxerxes moved southward, the rockrose accompanied it. Similarly, in its northward movement, the southern form of the Brown Argus was likewise controlled by the food- plant. As the Brown Argus in Durham, the so-called Castle Eden Argus, is restricted to the Magnesian Limestone, it follows that local rockrose populations must, like the insect, have been derived also from two sources, one Scottish and the other southern. Presumably, therefore, it is possible that the rockrose in Durham, if studied critically, would reveal signs of this two-fold origin-a possibility which we intend to investigate. Other insects besides Aricia medon produce evidence of this type, for we have shown (J.W.H.H., Ent. Record, 59, pp , 1947) that amongst other species, the Common Blue butterfly (Polyommatus icarus), feeding on Lotus corniculatus, and the Dark Green Fritillary (Argynnis aglaia), attached to Viola species, have also a double origin in Durham, so that our populations of Lotus corniculatus, Viola Riviniana, etc., must likewise have entered the area in two separate migratory waves, one coming from the north and the other from the south and east. If this holds true for the plants named, it is reasonable to infer that many of the populations of our commoner plants have also had twofold origins. In a different category to the biota just considered is another section of our Magnesian Limestone plants and insects. This group, apparently of purely southern origin, seems, if one may judge from the general ranges 24

26 of its individual members, to have reached England fairly late in the Post Glacial, or to have had its northward progress retarded by various ecological requirements. In any case, it appears to be approaching the northern limits of its British range in the area with which we are dealing. Examples of this distributional range amongst plants are supplied by Rosa micrantha, Euonymus europaea, Hypochoeris maculata, Cirsium eriophorum, Bryonia dioica, Daphne Laureola, Hottonia palustris, Tamus communis, Orchis Morio and Bromus erectus; insects with a similar range are exemplified by Sterrha fuscovenosa, S. subsericeata, S. inornata, Eupithecia inturbata and Procris geryon. Almost certainly, there exists a corresponding group of forms which have entered Durham from the north, and are here nearing their southern limits. However, their presence could also be explained on the basis of their possible survival in refugia in the nunatak areas of Upper Teesdale and Northwest Yorkshire. Clearly, under these circumstances, it is not possible to supply detailed lists, but amongst such plants are Pyrola minor, Rosa mollis, Cirsium heterophyllum, Allium Scorodoprasum and Equisetum hyemale. We must now deal with a small but important, section of plants the occurrence of which on our Magnesian Limestone seems, in several instances, to be exceedingly remarkable; these species are Trollius europaeus, Antennaria dioica, Primula farinosa, Pyrola rotundifolia, Salix phylicifolia, S. nigricans, Dactylorchis Traunsteineri, Cypripedium Calceolus, Sesleria caerulea and Juniperus communis. Some of these, undoubtedly, could with propriety be regarded as falling within the limits of the group referred to in the last paragraph. In spite of this, we think it best to discuss them separately. These species, with the exception of Cypripedium Calceolus and Dactylorchis Traunsteineri, still grow in Upper Teesdale. Moreover, one of them, the Bird's-eye Primrose, Primula farinosa, is regarded as one of the specialities of that area, so famous for its rare plants. It seems reasonable, therefore, to assume that, in some way, the existence of the plant on the Magnesian Limestone depends upon its history in Upper Teesdale. Until recently, the opinion was prevalent that the presence of the Alpine and Boreal plants in Upper Teesdale was best explained on the basis of perglacial survival in situ. Later, it was urged that the occurrence of nunataks in the area during the Glacial Period was sufficient to account for their presence. This position has now been abandoned in favour of a theory that the plants concerned reached Upper Teesdale in one of the milder Interstadial Phases of the Last Glaciation. It is considered that when this warmer phase passed and the land was once more ice- bound, the plants involved took refuge on the unglaciated nunataks. After the retreat of the ice, when favourable conditions prevailed once more, those which had not lost their mobility, are pictured as moving 25

27 out of their refugia to colonize newly opened areas. One such area seems to have been the Magnesian Limestone district of East Durham. However, it should not be forgotten that direct passage over the tundra-like tracts then available, interspersed as they were in Late Glacial and early Post-Glacial times with numerous lakes and marshes, was exceedingly difficult. Access to the lower tracts would be gained more easily down the Tees Valley, and then northward to the east of the Ferryhill and Skerne Lakes or their remains. Once the limestone was reached, some of them would be favourably situated, and possessing the requisite degree of tolerance, and meeting with but little competition, have survived. Such we believe to have been the course of events with Primula farinosa, Trollius europaeus, Antennaria dioica and Sesleria caerulea. Here it should be pointed out that the coastal colonies of P. farinosa are genetically separable from those in Upper Teesdale, a circumstance depending upon their long-continued isolation. Concerning the remainder of the plants singled out for special treatment, we have additional remarks to make. In the case of the two subalpine willows, Salix phylicifolia and S. nigricans, it is quite possible that their late Glacial and Post Glacial history is very similar to that outlined for Primula farinosa and its companions. Nevertheless, it should be made clear that, when we discovered S. phylicifolia at Bishop Middleham and near the Blackhall Rocks, we regarded it as a fairly recent wind-borne colonist on newly exposed limestone soils. Still, the existence of flourishing colonies in Newham Bog (v.-c. 68) indicates that it may have maintained itself in the nearby Morden and other Carrs until they were drained in the last century. It is even possible that it still grows in the remains of the old carrs. With its congener S. nigricans, the position is very different. Not only is it a firmly established inhabitant of the area, but, in addition, it has adapted itself to a new type of habitat; it forms dense low-growing thickets at many points along the coast. In some of these stations it grows in communities of which Primula farinosa, Pyrola rotundifolia and Dactylorchis Traunsteineri constitute an integral part. Besides, this, it abounds in the denes as a very ordinary shrub. To sum up, we are inclined to think that both species reached the Durham Magnesian limestone from refugia in the west in Late Glacial times. The differences in their present ranges we regard as depending upon the fact that S. nigricans shows greater adaptability and is everywhere less alpine in its predilections. Further, we regard Pyrola rotundifolia and Juniperus communis as having much the same history, the former travelling via bogs and marshes long since drained or dried up, and the latter utilizing hill slopes, banks and even marshes for its passage. Owing to the disappearance of the bogs, Pyrola rotundifolia has greatly contracted its range with us. On the other hand, the juniper has become almost extinct in the last fifty years in its old coastal stations on the 26

28 Magnesian Limestone owing to its inability to face competition with such coarse grasses as Dactylis glomerata recently introduced by human activities. The two orchids, the Lady's Slipper (Cvpripedium Calceolus) and the Dwarf Marsh Orchid idactylorchis Traunsteineri) can be considered here. The former, now extinct with us, used to occur in Castle Eden Dene in Durham (v.-c. 66), at Grassington and elsewhere in Midwest Yorkshire (v.-c. 64), more sparingly in the Yorkshire vice-counties 62 and 65 and, possibly in Westmorland (v.-c. 69). At first sight, this distribution suggests that, in the Lady's Slipper, we are dealing with a Post- Glacial invader which penetrated into Britain just before, or in, the Boreal Period, when the climatic optimum occurred. Then this island was continuous with the continent over the Straits of Dover and the southern portions of the North Sea. Against that inference can be brought the limited range of the orchid in Britain and the peculiarities of that range, ecological and otherwise. Very significantly, two lepidopterous insects, the Least Minor- moth (Phothedes captiuncula) and the Northern Brown butterfly (Erebia aethiops) possess an English distribution coinciding in general with that of the Lady's Slipper. Outside its English habitats, the moth flies in Clare and Galway in Ireland, whilst the Northern Brown can be taken freely in many Scottish localities. Judging from these facts, other workers and ourselves have concluded independently that both insects reached the British area in the First Interstadial Phase, only to be driven into suitable refugia in the Pennines when glacial conditions returned. In addition, both are thought to have occupied retreats elsewhere, the moth on Irish Atlantic fringes and the butterfly in similar Scottish stations. When the Ice Age ended, and favourable conditions supervened, both are regarded as having fanned out of these refugia to reach their present habitats. After comparing the English range of Cypripedium Calceolus with those of the two lepidopterous insect we believe that, in England, all three have had similar histories. Thus we conclude that the orchid is likewise of Interstadial origin, and there is nothing in its present conti- nental range to oppose this belief. Again, it seems likely that its former Post-Glacial distribution was much more extensive than that of the nineteenth century-and Ireland may well have been included. The other orchid Dactylorchis Traunsteineri is limited in Britain to a few isolated stations in North-east Yorkshire (v.-c. 62), Durham (v.-c. 66) and Fifeshire (v.-c. 85) although it appears elsewhere in Irish localities. Arguing from this distribution, we have been compelled to adopt the view that its history cannot differ widely from that of the moth, Phothedes captiuncula and other organisms of similar range. In other words, we think that it also is a survival from the First Interstadial Phase. Nevertheless, its marked discontinuous distribution demands some 27

29 comment. As a result of careful study in many localities, we have come to the conclusion that, in stations where it has encountered Dactylorchis purpurella, it has been hybridized out of existence. Traces of it have been found in a number of colonies of that species, which, therefore, should be regarded as hybrid swarms. Only where D. Traunsteineri grows alone, without admixture with D. purpurella, can the former manage to exist in a pure condition, although, even in these stations we have met with hybrids between D. Traunsteineri and D. Fuchsii. Lastly, we must draw attention to the fact that great changes are taking place in our flora. Many species like Carlina vulgaris, Hypericum montanum, Crepis taraxacifolia, C. mollis, Senecio squalidus, Dactylorchis purpurella, D. Fuchsii, Coeloglossum viride, Gymnadenia conopsea, Anacamptis pyramidalis and Ophyrys apifera are invading new areas, especially those in which recently disturbed soils are available. This is a remarkable phenomenon, and we are subjecting it to close observation. 28

30 THE GENUS RUBUS L. IN NORTHUMBERLAND AND DURHAM YOLANDE HESLOP-HARRlSON Baker and Tate's "New Flora of Northumberland and Durham" published in 1868 contains the last list of brambles from North Eastern England claiming in any way to be complete. Since that date, in a period in which the systematics of the group has been subjected to revision, the brambles of our area have received little attention compared with that which has. been lavished on those of Southern England. Random records have, however, been published occasionally, and the time now seems ripe to bring these together, and to add several new ones made during the course of my cytotaxonomic work on the group. A few explanatory words are perhaps necessary in presenting this account in relation to the systematic treatment. While the sexually reproducing taxa (represented in our area by Rubus chamaemorus L., R. saxatilis L., R. idaeus L.) are justifiably equated with sexual species in other flowering plant genera, it is extremely doubtful whether similar treatment should be accorded to the numerous forms in the Moriferi of the subgenus Eubatus. Cytological and breeding evidence (comprehensively surveyed by Gustafsson, 1943) has shown the European Moriferi to be composed of a complex of apomictic polyploids, the variation pattern of which seems to focus around several centres, some of which have been identified with existing sexually reproducing diploid forms present in the European area or elsewhere, and others possibly associated with sexual ancestors now extinct. The partial apomixis which must initially have led to the origin of the present wealth of forms is probably still an active factor, bringing into existence new true-breeding variants at intervals. Now that this situation has been revealed, the justification for providing every recogniz- able variant with a binomial seems slight, and it may be necessary in future treatments of the group to adopt a simpler and more realistic, as well as a more comprehensible method of approach. However, in the absence of agreement in the matter, the orthodox usage is employed here, and the taxa are treated as "good" species. A more detailed account of Rubus cytology is in the course of preparation, but for the sake of completeness the somatic chromosome numbers are indicated in the accompanying list, where such determinations have been made. * Cytological Studies in the Genus Rubus L" I. New Phyt., LIl, The earliest list of Rubi from our area, that given in 1805 by Winch, Thornhill and Waugh, included all the British species recognized at that date, namely R. saxatilis L., R. chamaemorus L., R. idaeus L., R. caesius L., R. fruticosus L., and R. corylifolius Srn. Smith, influenced to a certain extent by the early publications of Weihe and Nees von Esenbech on the German Rubus flora, in his "English Flora" (1824) recognized a total of eleven fruticose species. One of Smith's species, R. glandulosus, was recorded from the north-eastern area by Johnston in his "Flora of Berwick upon Tweed" (1829), in addition to R. caesius L., R. corylifolius Srn. and R. ftuticosus L., the last of which was probably interpreted as covering a wide range of non-glandular forms. It is often difficult to gather exactly what "R. fruticosus L." meant to the early botanists, since Linnaeus's type specimens consist of several taxa, none of which entirely agrees with his description, and later workers such as Arrhenius, Weihe, Nees von Esenbech and Smith all interpreted the species differently. Evidently many early botanists either did not look too closely into the wealth of variation that is possible amongst 29

31 the brambles, or considered the variations insignificant: thus Johnston, in naming only four brambles in north-eastern England in 1829, was either ignorant of the more critical approach of Weihe and Nees, or did not accept their findings. Winch was openly critical of the "pulverising" approach, and in 1831, in de-crying so-called species-mongers, he wrote in his "Observations on the Preceding Flora" : "... in determining the shrubby species there can be no difficulty unless we attempt to divide them into the endless varieties dignified by specific names by some German botanists." Yet he was influenced by the work, for in the Addenda to this flora he accepted one of Weihe and Nees "endless varieties" as being a "good" species, viz., R. afflnis, and he also included R. suberectus Anders. (R. nessensis Hall), noting that he did not think the northern R. suberectus was the same as that in southern England. Baker and Tate's "New Flora of Northumberland and Durham", published in 1868, marked a further real advance in the knowledge of our Rubi and, like that of Winch, it is particularly valuable since it gave the localities of the nineteen species found, Babington in his "British Rubi", published in 1869, frequently made use of the records of our northern workers Winch, Johnston and Baker in recording the distributions of the species. The latest summary of the distributions of the British Rubi is contained in the appendix to Roger's "Handbook of the British Rubi" (1900) in which use is made of the Watsonian vicecounty system. Apart from occasional records which have appeared from time to time in the "Vasculum", and a brief paragraph on our brambles in "The Three Northern Counties of England" (section on the flora compiled by J. W. Heslop Harrison and Ternperley, 1939) no other work from Northumberland and Durham has been published. The list given by J. W. H. Harrison and Temperley includes 30

32 R. suberectus, R. plicatus, R. affinis, R. koehleri, R. carpinifolius, R. rhamn- ifolius, R. pulcherrimus, R. villicaulis, R. radula and R. corylifolius ; the application of some of these names has changed since that date. In the following list my own records for the genus in our area are summarized, with those of Winch in " Flora of Northumberland and Durham" (1832; abbreviated as Win.); Baker and Tate in a "New Flora of Northumberland and Durham" (1868; Bak.); Babington in "The British Rubi" (1869 ; Bab.) ; and Rogers in "Handbook of British Rubi " (1900; Rog.). Occasionally other works are cited, and full details of these are given in the list of references. Localities not followed by an authority are of my own finding. The order of species follows that of the "List of British Species of Rubus" (Watson, 1946). Where the names used by the early authors are not in agreement with those of Watson's list, the most probable inter- pretation of the synonymy is provided. Since in many instances the intention of the early workers cannot be clearly interpreted, there remains a measure of doubt : where this is the case a question mark (? ) precedes the citation of locality. Where the authors themselves have indicated doubt, the sign follows the citation of locality. It has usually been possible to refer early records to vice-county sub-divisions (Garrett, 1930) or at least to vice-counties, but in the case of vaguer records, such as Babington's numerous references to "the Tyne area", this has not, of course, been possible. New county records published here for the first time are indicated by an asterisk. Chromosome numbers are quoted after the specific epithets for all the taxa in which I have made determinations. In each case the somatic number (2n) is that cited. Most of the determinations are from material from our own area; where the material originated from another area, the number is enclosed in brackets. Herbarium material from each of the plants which have been examined cytologically is in my possession, and will shortly be deposited in the Herbarium of the Royal Botanic Gardens, Kew. RUBUS SUBGENUS CYCLACTIS 1. R. saxatilis L. 28 *66A, 66c, 660, 66E ; 67B, 67c, 670 ; 68B Found mainly in the upland regions. High Force, Castle Eden Dene, Hown's Wood near Consett, Egglestone and Middleton ; on the banks of the Irthing in Allendale, Shewing Shields, north ofwallington, Hartburn, Whinetly Mill, W. Dibden-Win. Teesdale, "ascending to 550 yards in Harwood Dale and down the river as far as Eglestone", Burnhope, Gilsland and many Tyne denes near Bellingham and Hexharn, Calish woods near Alnwick, Roddam Dene, Langlee-ford ravine, "ascending to 500 yards in Dunsdale and Harthope Linn".-Bak. Deyne, Wallow Crag.-Bab. Stanhope--Nicholson Pigdon Banks near Morpeth-Report of Northern Naturalists Union "Vasculum"; * These are our recognized vice-county sub-divisions 31

33 2. R. chamaemorus L C, 66D, 66E; 68B Knoutberry Fell near Eglestone; Allenheads, Kilhope Law, Hedgehope, Cheviot; Simonside, Knaresdale, Coan Wood-Win. "The peaks at the head of Allendale, Weardale and Teesdale, scarcely descending below 1,500 ft.".-bak. "Abundant on the summit of all watersheds in W. Allendale, with one isolated patch near the road just below Coal Cleugh".-Hull, Subgenus IDEOBATUS 3. R. idaeus L A. 66B, 66C, 66D, 66E ; 67A, 67B, 67C, 67D ; 68A,688 This species is so well distributed throughout our counties that it is unnecessary to enumerate all the localities in which it is found. Subgenus GLAUCOBATUS 4. R. caesius L B, 66C, 66D, 66E; 67A, 67B; 68A, 68B The banks of the Tweed beyond Ord Mill and at Simonburn-Win. Common in thickets and hedges "ascending in Weardale above Stanhope and in Teesdale above Middleton, 820 ft. "- Bak. Blyth Links-Skinner, Near Corbridge-Black, In the hedges along the Morpeth-Mitford road; Birtley, Chester-le-Street, Ferryhill. (For R. saxatilis, R. chamaemorus and R. caesius numerous additional localities are cited from the Berwick area in Proc. Berw. Nat. Club, Vols. I-XXVI. See list of References). Subgenus EUBATUS Section 1 Suberecti 5. R. nessensis Hall (suberectus Anders.) (28).? 66E;? 67B,?67D;?68D Early records are of little value here since Baker, for example, included R. plicatus W. & N. with R. suberectus Anders., and Babington admitted that he may have confused R. suberectus Anders. with R. fissus Lindl. and R. plicatus W. & N.? Hareshaw Linn, N. of Bellingham- Win.? Twizell House Dene,? Kyloe Crags,? Alwinton, Harbottle,? Rothley Lake,? Slaley,? Corbridge Moor,?Staward,? High Force-Bak. 6. R. scissus W. Wats. (fissus auctt.) (28). 66? High Force-Bab., (see 5 above). V.-c. 66-Rog. var. acicularis Areschoug C Waldridge Fell 7. R. plicatus W & N (28) 67?;68?? High Force-Bab., (See 5 above). V-c. 67?; 68?-Rog. 8. R. fissus Lindl. (rogersii Lint.) (28).?66E; 67? High Force-Bab., (see 5 above): V.-c. 67-Rog. 9. R. affinis Win. See 13 below. Section 2 SPRENGELIANI. No species from this section has been reported in our area.-massey, Section 3 SILVATICI. 10.R. calvatus Ed. Lees ex Blox. 67D S. of Haydon Bridge-Bak. 32

34 11. R. carpinifolius W. & N.? 67D? Bardon Mill-Bab. 12. R. lindleianus Ed. Lees. 66? Between Dilston and Slaley, Willington?-Bak. The Tyne area-bab. V.-c. 66?-Rog. 13. R. nemoralis P. J. M. (selmeri Lindeb.) B, 66D; 67A;?68B Probably the R. cordifolius of Bak. and the R. affinis of Win.?By the Skerne near Darlington-Win.?Roddam,?Harbottle,?Corbridge Moor,?Bardon Mill,?Weardale between Eastgate and Westgate, and?whitley-bak. Hartford, North Seaton and Birtley Fell. var. microphyllus Lindeb. (28). 67 Two localities in Northumberland-Watson, R. laciniatus Willd B; 67B Hawthorn Dene-Harrison, This cultivated form, with its decorative laciniate leaves, has spread from gardens and shrubberies, and can occasionally be seen near to habitation as at Birtley and in the woods in Gosforth Park. It is probably a form of R. selmeri Lindeb. (Watson, 1928). 15. R. danicus Focke ex F. & G. 68 V.-c. 68-Rog. 16. R. macrophyllus W. & N B; 68B Akeld; West Buston?-Bak. Twizell Dene, Ancroft, Haggerstone, Cheviotland?-Bab. V.-c. 68?-Rog. Near Dinnington. 17. R. amplificatus Bd. Lees (macrophyllus var. amplificatus Lees). 28.?66; 67B; 68A, 68B Kyloe, Beal-Bak. Marsden: two herbarium sheets belonging to Baker, one from this locality, and the other from Boltby, Yorks., were said by Sudre to be R. stereacanthoides. Watson, who has seen the Boltby specimen says "it is clearly R. amplificatus Ed. Lees". The Marsden specimen was also referred to by Babington and Genevier in Bab., p Morpeth, Cramlington. 18. R. pyramidalis Kalt (28).?66D; 67;?68B? Langlee Ford,?Kyloe, 't Dilston,?Slaley,? Bardon Mill,? Langley Castle,?Weardale between Eastgate and Westgate-Bak. (According to Watson, the R. villicaulis W. & N. of Baker was probably this species). V.-c.67-Rog. 19. *R. egregius Focke B Near Morpeth and Stamfordham. 20. *R. atrocaulis P. J. M. 66C In our area near Brancepeth-Massey, *R. incurvatus Bab C; 67A, 67B Near Hartford, Crarnlington, Wolsington and Brancepeth. 22. R. villicaulis Koehl A,?67B,?67D? Stannington, '/ Bardon Mill-Bab. In our area at Hartford-Massey, *R. cryptadenes Sud A In our area at Hartford-Massey

35 24. R. polyanthemus Lindeb. (pulcherrimus Neum.), B, 66C; 67A, 678; 68 Baker may have intended this species when he described R. umbrosus Arrh. as "frequent in woods and thickets", and he included Winch's R.fruticosus here. V.-c.67; 68-Rog. Apparently widely distributed in our area Morpeth; Crarnlington, Plessey, Brunton, Hartford, Birtley, Ryton, and Brancepeth. 25. R. lindebergii P. J. M B; 67A V.-c. 67-Rog. Hartford, North Seaton, Birtley Fell, Ryton. 26. *R. errabundus W. Wats B Near Cramlington. Section 4 DISCOLORES. 27.R. ulmifolius Schott. (rusticanus (Mere.) Rog.). (14.) 67; 68 "In some districts the commonest form"-bak. (under R. discolor W. & N.). The Tyne area- Bab. V.-c. 67; 68-Rog. I have not seen this distinctive species in our area. *subsp. beteromorphus (Rip.) Sud. (R. fruticosus var. dalmatinus) Tratt B West Brunton. 28. R. argentatus P. J. M. (Winteri P. J. M.) 66 In one of the coast denes S. of Horden-Harrison, *R. falcatus Kalt B Near Dinnington. Section 5 VESTITI. 31.*R. schmidelyanus Sud B; 67B In our area near Morpeth, and on Birtley Fell-Massey, R. vestitus W. & N. (incorrectly leucostachys (Schleich.) Rog.) 67;?68 This has been interpreted as the R. leucostachys Srn. of Baker, by Watson.? Fourstones,? Corbridge,? Dilston,? Slaley,? Seaton Sluice-Bak. The Tyne area, Hartley, and Twizell House?-Bab. 32. *R. boreanus Genev C; 67 A, 67B, 67D North Seaton, Brunton, Chollerford, Brancepeth. 33. *R. wolley-dodii (Sud.) W. Wats B, 66C; 67B Cramlington, Brunton, Gosforth, Birtley Fell, Brancepeth. 34. R. cordifolius W. & N.?66D;?67A;?68B See 13 above. 35. *R. podophyllus P. J. M B Near Mitford. Section 6 ROTUNDIFOLII. 36.R. rotundifolius (Bab.) Blox. (drejeri Rog.) 68 V.-c. 68-Rog. 37. *R. mucronifer Sud. (mucronatus Rog.) 68 Alnwick Park. 34

36 Section 7 RADULAE. 38.R. radula Weihe ; 67; 68 "Frequent in hedges and thickets ascending Allendale to 250 yards"-bak. The Tyne andalne areas-bab. V.-c.67; 68-Rog. Brunton, Wolsington and Hartford. 39. R. discerptus P. J. M. (echinatus Rog., rudis W. & N.?) 67;? 68? Rothbury,? Thropton,? Holywell Dene,? Langley Castle-Bak. (Baker may have intended R. discerptus by R. rudis W. & N. for Babington wrote "in common with Mr. J. G. Baker, I am unable to distinguish R. discerptus P.J.M. from R. rudis W. & N."-Bab., p. 192.?Howick- Bab. V.-c. 67-Rog. 40. R. echinatoides (Rog.) Druce (radula subsp. echinatoides Rog.) ; 68 V.-c. 67 ; 68-Rog. Gosforth, Cramlington, Morpeth, Hartford, Alnwick Park. 41. R. rudis W.? 67;? 68 See 39 above. Section 8 APlCULATI. 43.R. bloxamii Ed. Lees. 66 The Tyne area, Weardale?-Bab. v,c. 66-Rog. 43. R. pallidus W. (28). See 50 below. 44. R. scaber W. (28). 68 Eglingham-specimen thus labelled in the herbarium of the British Museum. 45. *R. longthyrsiger Ed. Lees. 68 Alnwick Park. 46. R. rufescens L. & M. (rosaceus Bab.) (28). 66; 67A, 67B The Tyne area; Holywell Dene-Bab. V.-c. 66-Rog. Near Callerton. 47 R. spurius Neum. (infestus W.?).? 66;? 67;? 68? Kyloe ;? between Wark and Nunwick;? Dilston, Lennel,? Slaley ;? between Gatton and Staward;? Weardale between Eastgate and Westgate-Bak. (Baker perhaps meant R. spurius Neum. by R. infestus W., according to Watson). 48. *R. griffithianus Rog B In our area at Wolsington-Massey, R. phaeocarpus W. Wats. (babingtonii Rog.) (28). 67? V.-C. 67?-Rog. Section 9 GRANDlFOLlI. 50.R. glandulosus Srn. This name has been proclaimed invalid because the original description was based on herbarium specimens from several taxa (Watson, 1937). The name now given to one of the specimens (collected by Turner) in Smith's herbarium is R. turneri W. Wats. Winch, and later Babington, from Turner's specimen, considered R. glandulosus Srn. as referable to R. koehleri W. Baker considered R. pallidus W. and R. koehleri W. together, giving their localities jointly; Babington, too, believed R. pallidus to be no more than a variety of R. koehleri, and not worthy of specific rank. Rogers considered his R. koehleri subsp. dasyphyllus to be synonymous with Babington's R. pallidus W., and Watson also includes Baker's R. pallidus W. with R. dasyphyllus Rog., which is now raised to specific rank. Baker's R. koehleri W., Watson suggests, may be R. adenolabus W. Wats. Babington's R. humifusus W. is named R. pallidus W. by Rogers, and this is supported by Watson. The following localities are given for the above named forms :- R. glandulosus Srn. Jesmond Dene and Berwick-Win., or Win. ex Johnston. R. koehleri W. (including R. pallidus W.) 35

37 The common woodland bramble seen in hedges occasionally, in Weardale, Teesdale and Allendale-Bak. R. koehleri var. pallidus V.-c. 66-Bab. R. koehleri subsp. dasyphyllus Rog. V.-c. 66-Rog. R. humifusus W. (R. pallidus W. & N.) The Tyne area and Scotswood Dene-Bab. 51. R. tumeri W. Wats. See 50 above. 52. *R. furvicolor Focke B; 68 Birtley, Alnwick Park. 53. *R. mutabilis Genev. (apiculatus subsp. raduloides Rog. pro parte) 67B In our area near Morpeth-Massey, Section 10 HYSTRlCES. 54.R. hystrix W B; 68? The Tyne area; Ancroft?-Bab. Massey, V.-c. 68?-Rog. In our area near Brunton- Massey R. fusco-ater W. (28). 67A Whitley-Bab. 56. R. dasyphyllus Rog. See 50 above. 57. R. humifusus W. See 50 above. 58. R. infestus W. See 47 above. 59. R. adenolabus W. Wats B, 66C; 67B See 50 above. Plessey, Brunton, Gosforth Park, Dinnington, Cramlmgton, Stamfordham, Wolsington, Birtley, Brancepeth. Section 11 GLANDULOSI. 60.*R. leptadenes Sud. (28). 68 A1nwick Park. 61. R. hirtus W. & K. 66 Wolsingham-Harrison, R. bellardii W. 68 V.-c. 68-Rog. 36

38 Section 12 CORYLlFOLII. 63.R. corylifolius Srn. This is an epithet which has been given to several taxa and is not now used, except in the collective sense. Winch was clearly confused as to its identity since he regarded it as synonymous with R. vulgaris Lindl., and stated that where it occurred "in woods and sheltered denes this shrub becomes almost an evergreen, and is then R. macrophyllus of Lindley's Synopsis". 64. *R. warrenii Sud. (dumetorum var. concinnus Rog.) B; 67B Brunton, Dinnington, Cramlington, Birtley. Apparently a frequent hedgerow bramble in our area. 65. R. sublustris Ed. Lees. 35.? 66B; 67B? Extending into Weardale, Teesdale and Allendale-Bak. (Under R. corylifolius Srn., and see 63 above). V.-c. 68-Rog. Wolsington; Stamfordham. 66. R. conjungens (Bab.) W. Wats. 28, (35). 67B;68 V.-c. 68-Rog. Brunton, Wolsington. 67. R. babingtonianus W. Wats. (althaeifolius Bab.) 28, (35). 66;67B The Tyne area and Durham-Bab. Gosforth Park. 68. *R. tuberculatus Bab. (35). 67B Near Morpeth. 69. R. myriacanthus Focke (diversifolius (Lindl.) Rog.) (35). 67B, 67C, 67D ; 68A W. Buston, Beal, Rothbury, between Long Horsely and Morpeth, Wark, Bardon Mill, Dilston-Bak. (under R. diversifolius Lindl.) 70. *R. rubriflorus Purch. 67A In our area, Hartford-Massey, *R. scabrosus P. J. M. (dumetorum var. ferox Rog.) (35). 68 Alnwick Park. Of the twenty-two new vice-county records published above, many involve considerable extensions of known ranges. Those listed below, with their previously known ranges are probably the most interesting :- R. atrocaulis P. J. M.-West Kent (Watson, 1927b). R. villicaulis Koehl.-Abundant in Scotland and fairly frequent in W. England and Wales (Rogers, 1900). Also frequent in Surrey, S. Essex, S. Hants., W. Kent, Berks., Oxon., Bucks., S. Lincs. (Watson, 1931). R. cryptadenes Sud.-W. Kent, Cornwall, Devon., Somerset., Berks., Oxon., Glos., and Cardigan. (Watson, 1930a). R. schmidelyanus Sud.-S. Beds. (Avery and Watson, 1947). R. wolley-dodii Sud.-Found only in Cheshire. R. griffithianus Rog.-N. Devon, Carnarvon., Anglesea (Rogers, 19(0); West Kent and Surrey (Watson, 1927a). R. mutabilis Genev.-Surrey (Watson, 1930a). R. hystrix W.-Surrey, S. Bucks., and W. Kent (Watson, 1934). R. rubriflorus Purch.-Locally abundant in Derby (W. R. Linton ex Rogers, 1900). All the above species except two are here recorded from single occurrences in our area, but it is interesting to note that these two-r. wolley-dodii and R. schmidelyanus-are much more widely distributed: R. wolley-dodii for instance was found in five distinct localities in vicecounties 66B, 66C and 67B, and R. schmidelyanus in single localities in the two vice-counties 66B and 67B. 37

39 Probably the most outstanding absentee in our area is R. sprengelii W. which is recorded from at least thirty-seven vice-counties (Rogers, 1900) and extends as far north as Wigton (Rogers, 19(0) and Inverness-shire, where I have seen it growing on the isle of Rhum. Others which one might have expected in our own area from their known British distributions include R. rhombifolius W. (Watson, 1949), R. flexuosus M. & L. (R. saltuum F., Rogers, 1900; Watson, 1932), R. pallidus W. (Rogers, 19(0), R. euryanthemus W. Wats., R. turneri W. Wats. (Watson, 1937) and R. balfourianus Blox. ex Bab. (Rogers, 19(0). It seems probable that further work in the area would be likely to reveal the presence of some of these. REFERENCES AVERY, C., and WATSON, W. C. R. (1947): The Brambles of Middlesex. Lon. Nat., 1947, BABINGTON, C. C. (1869): The British. Rubi : an Attempt to discriminate the Species of Rubus known to inhabit the British. Isles. London. BAKER, J. G., and TATE, G. R. (1868) : A New Flora of Northumberland and Durham. Nat. Hist. Trans. Northd. and Durham, II, BLACK, J. G. (1933): Mid-Tyne Phenology. Vasculum, XIX, 108. CLAPHAM, A. R. (1946): Check-list of British Vascular Plants, Appendix 1, by W. C. R. Watson. Journ. Ecol., XXXIII, GARRETT, F. C. (1930): A Scheme to simplify recording in Northumberland and Durham. Vasculum, XVI, GUSTAFSSON, A. (1943): The Genesis of the European Blackberry Flora. Lunds Universitets Arsskrift, Bd. 39. HARRISON, H. H. (1925) : Notes and Records. Vasculum, XII, 38. HARRISON, J. W. H. (1915, 1916, 1920): Notes and Records. Vasculum, I, 60; rr, 29; XVI, 24. HARRISON, J. W. H. and TEMPERLEY, G. W. (1939) : The Flora of the Three Northern Counties of England; in The Three Northern Counties of England. Northumberland Press. HARRISON, Y. HESLOP-(nee MASSEY). 1948): Rubus specimens from Northumberland and Durham ex British Flowering Plants and Modern Systematic Methods. Botanical Society of the British Isles Conference Report, 1948, 80. HULL, J. E. (1916): Flowering Plants of an Upland Dale. Vasculum, II, 3. JOHNSTON, G. (1829): A Flora of Berwick upon Tweed, I, MASSEY, Y. (1948) : See under HARRISON, Y. HESLOP-. NICHOLSON, J. B. (1933) : N. N. U. Report. Vasculum, XIX, 108. N. N. U. REPORT, (1934): Vasc., XX, 107. PROC. BERw. NAT. FIELD CLUB: Records for Rubus saxatilis L.-I, 68; IT, 48 ; LV, 210; IX, 219, 284. Records for R. chamaemorus L.-II, 164; VI, 303 ; X, 24, 275; XII, 475; XIII, 70; XVI, 273; XIX, 118; XX, 183 ; XXIV, 202, 368; XXV, 26; XXVI, 24, 308. Records for R. caesius L.-III, 3 ; VII, 365; X, 39; xn, 188: XV, 220. ROGERS, W. M. (1900): Handbook of the British Rubi. London. SKINNER, M. (1933): List of Exhibits. Vasc., XIX, 146. SMITH, J. E. (1824): English Flora. London. WATSON, W. C. R. (1927a): Some Brambles of Kent and Surrey. B. E. C. Rep. WATSON, W. C. R. (1927b, 1928, 1930a, 1932, 1934): The Brambles of Kent and Surrey 1, 2, 4, 5, 6. London Naturalist, WATSON, W. C. R. (1930b): Bramble Notes, B E.C.Rep WATSON, W. C. R. (1931) : Some British Rubi, New and Old. B. E. C. Rep WATSON, W. C. R. (1937): Notes on Rubi. Journ. Bot., LV, ; WATSON, W. C. R. (1946): List of British Species of Rubus. See Clapham, A. R. 38

40 WATSON, W. C. R. (1949) : Weihean Species of Rubus in Britain. Watsonia, I, WEIHE, and NEES, VON E. ( ): Rubi Germanici. Uberfeldae. WINCH, N. J. (1832): Flora of Northumberland and Durham; Addenda to Flora; Observations on the Preceding Flora. Trans, Nat, Hist. Soc. Northd. and Durham, 11, 34-35; 134; WINCH, N. J., THORNHILL, J. and WAUGH, R. (1805): The Botanists' Guide through the County of Northumberland. I, Newcastle upon Tyne. 39

41 A LONG POLLEN DIAGRAM FROM NORTHUMBERLAND KATHLEEN B. BLACKBURN During the investigation of local peats, of which an account appeared in this publication in 1932 (Raistrick and Blackburn), search for a deposit which had a continuous record from the end of the Ice-Age till present times was unsuccessful. More recently, a number of deep peats has been discovered in the west of Northumberland, and examination of the pollen statistics of two of them shows that these peats are of the desired type. Although the two sites are situated some fifteen miles apart, their pollen diagrams are very similar. The one from Broadgate Fell, near Ridsdale, will be described here for use as a standard diagram. It is intended to report on the second, Falstone Moss, in much fuller detail elsewhere. The description of this Broadgate Fell peat will serve to illustrate changes in technique and methods of presenting results which have taken place during the last twenty years and, at the same time, can be used for comparison with the shorter profiles described by Mr. Joh. Precht in a paper on the upper forest layer on Cold Fell, which appears in this number of the Transactions. The peat occurs at an altitude of 900 ft., just off the Corbridge to Woodburn road, near Ridsdale, The locality, though so near the road, is part of wild hilly land which has clearly not been disturbed except by an occasional sheep. The samples for pollen analysis were taken with a Hiller peat-borer, and the actual peat samples were peculiarly difficult to interpret. For the present purpose, records of macroscopic remains are limited to noting the layers at which wood was recorded: these were at depths of 200, 270, 410, 500 and 550 cms, respectively. The evidence is clearly insufficient but, as far as it goes, suggests the possibility of there having been two periods in which the bog was sufficiently dry to support trees: one before the rise of the alder pollen and the other just before heather pollen increased to high values. On consulting the pollen diagram it will be observed that it is constructed in a different manner from those published in 1932 since the curves for tree pollen, non-tree pollen and spores are each drawn separately. This gives a much clearer picture of the fluctuations in quantity of each kind of grain. A closer series of samples is also used, and this gives a more reliable set of curves. The zonation used is that 40

42 41

43 devised by Godwin (1940) for English diagrams. Broadly speaking, it corresponds to the Blytt-Sernander periods in this way: IV (birch-pine zone) is the Arctic period, V and VI (pine and pine-hazel zones) are the Boreal, VII (alder, oak, elm, lime zone) is Atlantic and VIII is Sub- Atlantic. The poorly understood Sub-Boreal period is recorded in the layers just below the VII-VIII transition. The shapes of the individual curves agree with those in Godwin's East-Angllan type, and the zone boundaries have been inserted according to his scheme, but, clearly, the relative amounts of the several pollens are different in the more northern latitudes. Birch never falls below 20 % and a marked recovery is to be seen in the upper part of the diagram. Elm is well represented, and shows clearly the falling off at the end of zone VIIa which has been used so successfully by Godwin (1945) in correlating the peats around the North Sea basin. Oak is very much less in quantity in the North as is also lime, which is so scanty that the curve is broken. The high birch percentage is no doubt responsible for the rather less quantity of alder represented. The hazel maximum, in the earlier part of zone VI on Broadgate, was much more accentuated than, for instance, that on the old Decoy diagram (Godwin 1940), and indeed there is a bigger percentage throughout the hazel curve. Beech was not found, but it occurred in minute quantities at Falstone Moss in the middle of Zone VIII. Thus, as far as trees are concerned, the patterns of forest development for East Anglia and Northumberland agree, but the actual percentages for the various trees differ. The non-tree pollen and spores are much more closely related to the type of ground on which the deposit occurred, since this will influence the plant succession on, and near, the bog. Zone IV shows small peaks on the curves for all the recorded non-tree pollens, heather, grass and sedge, and this suggests, at once, wide open spaces between the patches of birch forest which are indicated by the tree pollen. Fern and sedge have peaks in zone VI, and this probably corresponds to a fen phase in the bog itself, though, in that case, the peak of Sphagnum at 550 cms. is unexpected. The upper part of the diagram needs the closest scrutiny, especially as the structure of the peat does not supply the hoped for clues concerning the VII-VIII (Sub-Boreal-Sub-Atlantic) transition. The more highly decomposed layer of peat found on the continent, and in many places further south, as for example at Tregaron (Godwin & Mitchell 1938), and referred to as the Grenz-horizont, has not been detected in our area so other features must be used as zone boundaries. In describing a peat from Barra, Outer Hebrides, it was found that a change in consistency of the peat, from a more to a less decomposed state, corresponded closely to the level at which the quantity of heather pollen suddenly increased, and this layer was taken to be the VII-VIII zone boundary. In a number 42

44 of other peats, this correspondence was found but, as stated before, on Broadgate Fell the peat evidence was poor. On the other hand, investiga- tion of the tree curves suggests that here zone VIII could be called the hazel-alder-birch zone. The sudden rise of heather is accompanied by increases in hazel and alder, and in the Falstone diagram (unpublished) birch also rises conspicuously at this level. Another interesting feature of zone VIII is the rise in quantity of sedge and grass pollen towards modern times. This feature seems to be of some local significance, at least, since it also occurs at Falstone. Conway (1947), working on Ringinglow Bog, recognizes a zone VIII modern which has similar features, but, as her zone VIII is very different, it would be unwise in the present state of our knowledge of these younger peats to attempt to equate them. To sum up, examination of the pollen statistics of the Broadgate Fell peat shows the main features of forest development recognized in Southern England, but the relative quantities of tree pollen clearly point to its origin on northern fells. The upper part of the diagram is complete to modern times but, in spite of that, we have still very little real knowledge of the history of the vegetation of the last 800 years in this area, and it is in this connection that Mr. Precht's paper, which accompanies this, is particularly valuable. REFERENCES BLACKBURN, K. B., "On a Peat from the Island of Barra, Outer Hebrides" New Phyt. 45, CONWAY, V. M., "Ringinglow Bog, near Sheffield, Part I, Historical". J. Ecol., 34, GODWlN, H., "Pollen Analysis and Forest History of England and Wales". New Phyt., 39, , "Coastal Peat-beds of the North Sea Region, etc.", New Phyt., 44, GODWIN, H., and MITCHELL, G. F., "Stratigraphy and Development of Two Raised Bogs Dear Tregaron, Cardiganshire." New Phyt., 37, RAISTRlCK, A., and BLACKBURN, K. B., "The Late-Glacial and Post-Glacial Periods in the North Pennines. Part Ill; the Post-Glacial Peats." Trans. Northern Nat. Union, 1, Part 2,

45 ON THE OCCURRENCE OF THE "UPPER FOREST LAYER" AROUND COLD FELL, N. PENNINES JOH. PRECHT The paper presented here deals with the height distribution of Sub- Boreal forest layers in part of the Northern Pennines, some 12 miles east of Carlisle. It is based on investigations carried out whilst the author was a prisoner of war in the north of England. The work was made feasible through the help of the Y.M.C.A. and W.S.R. who kindly made a microscope available. The author would like to express his gratitude to Miss K. B. Blackburn, D.Sc., King's College, Newcastle upon Tyne, who always encouraged his work. He also sincerely thanks his teacher, Dr. P. W. Thomson. Like the Sub-Boreal forest layers in bogs of the Continent, the extension of forests in the Sub-Boreal has left behind the "Second Forest Layer" or "Upper Forestian" in peats of Great Britain. The height- distribution of this layer was examined in the Cold Fell area. Cold Fell is one of the higher peaks of the Pennine Uplands: it reaches a height of 2,039 ft. (621 m.), and is situated on the northern end of the ridge. The terrain is built up into a tableland of coarse carboniferous sandstones, and is dissected by the deep valleys of burns fed by the bogs. The soils in the highlands are very shallow and poor, and rock is often exposed. The whole area is more or less covered with blanket peat; a moderately thick peat cover which accommodates itself to the unevennesses of the ground. This blanket peat, according to Tansley (1939), forms under conditions with an annual rainfall of more than 60 in. (1,500 mm.), or in localities with high humidity of the air and a rainfall of 50 in. (1,250 mm.). The peat cover is cut by numerous erosion channels. The main vegetation types of the area are Calluneta and Vaccinieta. True Sphagnetum is rare. On places without peat cover, Nardeta and also Molinieta and Junceta occur. Pteridieta are represented on valley slopes, on mineral soil and on dried-out peat. The uplands themselves are absolutely treeless and bushless. In the valleys of burns Sorbus aucuparia reaches about 1,450 ft. (450 m.) above sea-level, whilst alder, birch and some willow-bushes reach about 1,300 ft. (400 m.). Only Sorbus shows satisfactory regeneration. The present height limit of sub-alpine birch woods in Scotland may reach 2,000 ft. (560 m.), whilst the limit of tree growth, represented by Sorbus is 2,600 ft. (790 m.) Tansley (1939). Brockmann-Jerosch suggests that this low limit of woody vegetation is due to the summercool Atlantic climate. 44

46 Factors tending to prevent tree growth in the highlands are shallow- ness of soil, with the accompanying tendency of thin peat layers to dry out, and the exposure to winds of most highland localities. Quite naturally, sheep-farming, continuous throughout the year, also restricts tree growth. In erosion channels, etc., places were searched for where the forest layer reached its highest limit, or where only a brushwood layer was represented. At these places, clear profiles were exposed with a spade, and peat was taken in specimen tubes for pollen investigation. The sites were located with the help of a one-inch topographical map (1:63360), and the height above sea-level read off from this map. The data of height are accordingly approximate only. Preparation of samples for pollen analysis was done in the ordinary way with caustic potash solution. The map shows the situation of the 12 sites for which pollen diagrams were constructed. Unfortunately, it is only possible to publish one of these, and profile No. 7 from Hartleyburn Common has been chosen as the most representative. This is one of the N.E. group of profiles examined. Samples 2, 3, 4, 5, 6, and 7 were all taken relatively close to one another, as can be seen from the map, and are in essentials alike, although their depths vary from 80 cms. to 140 cms. and their altitudes from No. 2. at 900 ft. (274 m.) to Nos. 4 and 6 at 1,300 ft. (396 m.). All, except No. 2, show brushwood at the base, and in one place, not examined for pollen, a brushwood layer was observed as high as 1,400 ft. In profiles 2, 4, 5, and 6 the uppermost layers of wood peat contain definite rooted birch stumps up to 30 cms. in diameter, but even the brushwood layer represented in the diagram for No. 7 consists of stems up to 8 ems. in diameter. The E. and S.E. sides of the fell are quite devoid of peat cover, and further up, where peat occurs, there is little brushwood. At one place investigated, however, an example of a forest layer near its upper limit occurred in a slight depression (Site 2). This layer was marked out by tree trunks -over-thrown by wind, lying more or less to the N.E. Similar trees were seen 2 or 3 miles to the east, at Asholme Common, and at a similar distance to the North, at Hot Moss, on Blenkinsop Common. No signs of wood burning, such as are well known from Sub-Boreal forest layers on the continent, were to be seen in this area. A feature which may be significant is that, at higher altitudes, e.g., No. 4, the layer of small stumps appears on deeper peat than that lower down the slopes. Here also it was noticed that the forest seemed denser on the North side of the ridge, and only a sparse bushwood layer occurred to the South. Turning to the pollen records, it was observed that tree pollen was rich in the layers of brushwood peat, but in the less humified peats above 45

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