A NOTE ON A LATE-WEICHSELIAN SPLACHNUM CAPSULE FROM SCOTLAND

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1 New PhytoL (1969) 68, A NOTE ON A LATE-WEICHSELIAN SPLACHNUM CAPSULE FROM SCOTLAND BY A. P. CONOLLY AND J. H. DICKSON Botany Department, University of Leicester and Botany School, University of Cambridge (Received 5 May 1968) SUMMARY A single capsule of the coprophilous genus Splachnuni is reported from deposits of Late- Weichselian (Late-glacial) age in Berwickshire. Other Quaternary records of moss sporophytes are briefly discussed. Whitrig Bog, first studied for plant remains by Mitchell (1948) and later by Conolly (1961), lies to the east of the MofiFat Hills and to the south of the Lammermuirs, about 3 miles north of the Tweed and at 435 ft O.D. (133 m). The plant-bearing strata resting in a hollow in boulder clay show a typical Late-glacial sequence of an organic mud and marl lying between lower and upper silty clays. The three layers are correlated with zone II, and zones I and III respectively. The sub-fossil flora of these strata is among the richest found in the British Isles. It includes such interesting finds as Koenigia islandica L., Luzula spicata (L.) DC, Saxifraga cf. rivularis L. or cernua L. and Papaver sect, scapiflora, a non-british taxon (Conolly, 1957, 1961). In a bryogeographically significant moss assemblage of some twenty-five taxa, Rhytidium rugosum (Hedw.) Kindb., Scorpidium turgescens (T. Jens.) Loeske and Timmia sp. are particularly noteworthy. All three, and Scorpidium turgescens in particular, are excellent examples of relict species known to have had widespread, more continuous ranges in Weichselian times (Dickson, 1967); at present they exhibit highly disjunct patterns. Such species as Camptothecium nitens (Hedw.) Schimp., Drepanocladus revolvens (Turn.) Warnst. and Scorpidium scorpioides (Hedw.) Limpr. demonstrate the presence of rich fens in both zones II and III. A range of base-rich, open terrestrial habitats, probably more strongly developed in zone III, is indicated by Distichium capillaceum (Hedw.) B., S. & G., Ditrichum flexicaule (Schwaegr.) Hampe, and Timmia sp. amongst others. A few taxa (Polytrichum and Rhacomitrium spp.) point to base-poor conditions. A Splachnum capsule was extracted from the clay deposited during zone III. No leaves referable to Splachnum were to be found amongst the numerous zone III moss fragments. This find is exceptional, because of the rarity of any sub-fossil Splachnaceae, coupled with the scarcity of sub-fossil capsules in general. The capsule, detached at the junction of the seta and apophysis, bears only stumps of the peristome; the calyptra and operculum are missing. There are spores (diameter c. 12 n) by the opening of the theca as well as alongside the exserted columella and the apophysis. Although the apophysis is somewhat battered and mounting of the specimen has resulted in flattening, the cell structure of the capsule is clear (Plate i). 197

2 198 A. P. CONOLLY AND J. H. DiCKSON The large apophysis and upright dehiscence are indicative of the Splachnaceae; and on the grounds of the exserted columella and the relative proportions of the theca and apophysis, the specimen can be referred to Splachnum. The only other genus needing consideration on the basis of general shape is Tetraplodon, but this is eliminated by the cell structure which is clearly that of Splachnum. The shape of the apophysis eliminates 5. rubrum Hedw. and S. luteum Hedw. and also S. ampullaceum Hedw. (Figs. 91 and 92 of Nyholm, 1956); the apophysis of the last tapers very gradually below. The form of the stomatal complexes eliminates S. vasculosum Hedw. which has each stoma surrounded by a marked pattern of elongate, radiating cells often fourteen in number; the stomata of S. ampullaceum have similar patterns of surrounding cells. However, S. sphaericum Hedw. shows least differentiation, there being fewer, often eight or nine, less elongate cells (see the plates of Splachnum in Bruch, Schimper and Gumbel (1851) and Fig. 43 of Brotherus (1923)), as also has the sub-fossil specimen (see Plate ib). On the form of the stomatal complexes and the overall shape of the capsule the specimen is therefore assigned to S. sphaericum. S. sphaericum, a freely fruiting species, is widespread at the present time in upland areas of the British Isles from Devon northwards. It is usually found on the excreta of mammals, particularly the droppings of deer, sheep and cattle. The environment of the Late-Weichselian period in the British Isles must have heen favourable for the Splachnaceae. Sub-fossils show that shallow mires abounded; the widespread distribution of skeletons of giant Irish deer, reindeer and elk prove no lack of habitats. Perhaps excreta of elk provided the habitat for the Splachnum described here; a skeleton was extracted from the Whitrig deposit (Mitchell and Parkes, 1949, p. 307). More than probable as it is that Splachnaceae were abundant in Late-Weichselian times, there is no confirmation from sub-fossils, which are exceedingly scarce. There appear to be only two other published records, the first being that by Anderson (1896) who recovered Splachnum vasculosum from a Post-glacial fiuviatile deposit in northern Sweden. The second, from the Late-Weichselian zones I and II of Mapastown, Co. Louth, Ireland, is given by Holmen merely as 'Splachnaceae' without amplification (Mitchell, 1953); this site yielded two skulls of the giant Irish deer. The scarcity of sub-fossils of this family may well be the result of differential preservation, a phenomenon often invoked to explain the lack of taxa which, on ecological grounds, might be expected frequently in the sub-fossil state (Gams, 1932; Steere, 1941). The characteristic large leaf size and very lax areolation lend plausibility to this assumption. Moreover, these features must render extraction difficult without great risk of fragmentation. The discovery of the Splachnum capsule is the more remarkable as moss sporophytes are seldom found in the sub-fossil state, apart from those of Sphagnum in Post-glacial peat. Recently in Cambridge sporophytes have been found of several species such as Furhynchium speciosum (Brid.) Milde, Grimmia apocarpa Hedw. and Distichium (the latter two are tentative identifications; Dickson, 1965). However, the number of records in the literature is small; good examples are Neckera complanata (Hedw.) Huben (Bronze Age, Yorkshire; Allison and Godwin, 1947), Folytrichum commune Hedw. {c. A.D. 500 near Oslo; Stormer, 1949) and unidentified bryoid capsules from two British Weichselian sites (Coope, Shotton and Strachan, 1961; Dickson, 1963). Sporophytes of at least ten species have been recovered from Russian Quaternary deposits by Abramov, Abramova and Kipiani (1965) who tentatively identified Encalypta vulgaris Hedw. and Stegonia latifolia (Schwaegr.) Vent., species seldom if ever found as sub-fossil gametophytes.

3 THE NEW PHYTOLOGIST, 68, i PLATE 2j^ (a) The capsule with detached fragments of peristome beside the exserted columella, (b) A stoma showing eight or nine surrounding cells. Photographs by F, T. N, Elborn, A, P, CONOLLY AND J, H, T>\CVJS,O^ LATE-WEICHSELIAN SPLACHNUM CAPSULE (facing page 198)

4 A Late-Weichselian Splachnum capsule 199 Slightly different is the case of Fncalypta rhabdocarpa Schwaegr. No capsules have been reported but material from the Lea Valley Arctic Bed (Warren, 1912) bears setae lacking capsules. This species has also been recorded from Mapastown, Ireland (zone II, Mitchell, 1953) and ConoUy (unpublished) has found numerous calyptrae of an Encalypta, possibly E. rhabdocarpa, in the Whitrig deposits. It is worth noting that Colinvaux (1964) alone has reported spores, which are large and distinctive (Erdtman, 1957, p. 107). For the most part, the sporophytes mentioned above are those of species which fruit freely at present and which are well known as gametophytes in Quaternary deposits. REFERENCES ABRAMOV, 1. L, ABR.MVIOVA, A. L. & KIPIANI, M. G. (1965). Sporogonia of mosses from the Quaternary deposits of the TJ.S.S.R. Nov. sist. nlzch. Rast. 1965, 285. (In Russian.) ALLISON, J. & GODWIN, H. (1947). Appendix B. Report on plant material associated with the Ferriby Prehistoric Boats. Proc. prehist. Soc, 13, 138. ANDERSSON, G. (1896). Die (jeschichte der Vegetation Schwedens. Bot. Jb., 22, 433. BROTHERUS, V. F. (1923). Die Latibmoose Fennoskandias. Helsingfors. BRUCH, PH., SCHIMPER, W. PH. & GUMBEL, TH. (1851). Bryologica Europaea, Volume III. COLINVAUX, P. A. (1964). The environment of the Bering land bridge. Ecol. Monogr., 34, 297. CoNOLLY, A. P. (1957). The occurrence of seeds of Papaver sect, scapifiora in a Scottish Late-glacial site. Veroff. geobot. Inst., Zurich, 34, 27. CoNOLLY, A. P. (1961). Some climatic and edaphic indications from the Late-glacial flora. Proc. Linn. Soc. Loud., 172, 56. COOPE, G. R., SHOTTON, F. W. & STRACHAN, I. (1961). A Late Pleistocene fauna and flora from Upton Warren, Worcestershire. Phil. Trans. R. Soc. B, 244, 379. DICKSON, J. H. (1963). Appendix, Bryophyta. In: C. A. Lambert et at, A flora and fauna from Late Pleistocene deposits at Sidgwick Avenue, Cambridge. Proc. Linn. Soc. Lond., 174, 13. DICKSON, J. H. (1965). Historical biogeography of the British moss flora. Cambridge University Ph.D. dissertation. DICKSON, J. H. (1967). The British Moss Flora of the Weichselian Glacial. Rev. Palaeobot. Palynol. 2, 245. ERDTMAN, G. (1957). Pollen and spore morphology Plant Taxonomy. In: An Introduction to Palynology, Vol. IL Stockholm. GAMS, H. (1932). Quaternary distribution. In: Manual of Bryology. (Ed. by F. Verdoorn), pp The Hague. MITCHELL, G. F. (1948). Late-glacial deposits in Berwickshire. New PhytoL, 47, 262. MITCHELL, G. F. (1953). Further identifications of macroscopic plant fossils from Irish Quaternary deposits, especially from a Late-glacial deposit at Mapastown, Co. Louth. Proc. R. Ir. Acad. B, 55, 225. MITCHELL, G. F. & PARKER, H. M. (1949). The Giant Deer in Ireland. Proc. R. Ir. Acad. B, 52, 291. NYHOLM E (1956). 7//«s«raterfMo5i F/ora o/fennoscandm. IL M«ia. Fasc. 2. Lund. STEERE, W. C. (1941). Pleistocene mosses from the Aftonian interglacial deposits at Iowa. Pap. Mich. Acad. ST0RMER', P.'(i949). Moser funnet i Ratoehaugen ved utgravningen B/yma, 7, 92. WARKEN, S. H. (1912). On a Late-glacial stage in the valley of the River Lea. Q. Jl geol. Soc. Lond., 68, 213.

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