the various species of the family Pteridaceae of the Western Chats of South India.

CHAPTER 5 MICROMORPHOLOGY 5.1 INTRODUCTION India is one of the richest in its Pteridophytic flora which could be attributed to the richness of forest wealth in the mountains of Central India, Eastern and Western Ghats of peninsular India. Extensive work has been done on taxonomy of Indian ferns by number of workers (Beddome, 1883; Clark, 1880, Panigrahi and Dixit, 1966,1969; Dixit and 'ohra, 1984; Jasmir and Rao, 1988; Biret al., 1980, 1989, 1991; Kachroo et al., 1989; Vasudeva et al., 1990; Manickam and Irudayaraj, 1992; Nayar and Gee Varghese, 1993 and Khullar, 1994) but they did not workout detailed micromorphology (Venation, Stomata and Spore morphology) of the various species of the family Pteridaceae of the Western Chats of South India. 5.2 REVIEW OF LITERATURE 5.2.1 Venation Leaf venation patterns in ferns have provided valuable information to taxonomists from the beginning. This contrasts with angiosperm systematic in which venation pattern is usually missing in descriptive studies (Rury and Dickason, 1977). The venation pattern of the fern leaf has been studied in detail by many PteridologistS including EttingshauSen (1865) and Gobel (1922). Presl (1851) used this feature extensively in his classification of the genera, a system now generally regarded absolute in many instances. The venation pattern, like some other features such as the soral arrangement and Bolbitis crenata is leaf shape is subject to parallel evolution. Thus the venation pattern of similar to that of the meniscoid Thelypteroid ferns. Schumann (1915) illustrated a progressive series of venation pattern comprising mensicoid ThelyptcliS species and 63

some Bolbitis species which she thought closely related. Another five example of parallellism is developed by the venation patterns of Bolbitis heteroclita a nd PteridoblechflUm accuminatum (Hen nipman, 1977). Pray (1960, 1962) has studied the ontogeny of venation in two ferns, NephroiepiS He concluded that the pattern of ontogeny in these two unre!c'.ted and RegenellidiUm. ferns is similar and it is probably the same in other leptosporangiate ferns with dichotomous venation. Hara (1964) investigated venation pattern in Onoclea sensibilis. Iwatsuki (1963) studied the venation pattern in ThelypteriOd ferns and explained, the formation of gonopterioid or meniscoid and pleocnemiod venation patterns. Panigrahi and Dixit (1969) studied the venation pattern that occur in Bo!bities. Holttum (1973) studied the venation pattern of the ThelypteriOd ferns which showed three types of venation. Pinnate, with or without forking, semi reticulate and reticulate. AnastofllOSiflg of veins shown by some members of this family is considered as an advanced characters developed in association with deep lobing of leaflets. Nair and Das (1974, 1977) studied the venation pattern in the genera of Adiantum. udied the different types of venation pattern tht oc r n Bolhiti.s. Hennipmann (1977) st A considerable number of species has been found mainly or exclusively UOfl characteristics in the venation pattern. Kato (1977) studied the venation pattern in Athyrium and its allied genera of Japan and discussed the importance of this character in the classification of Athyriod taxa. Holttum (1975) observed the venation pattern in Athyrium species and reported that the venation pattern of Athyrium excientum is superficially similar to that of species of cyc/qsorus. Padala and Bhardwaja (1987) investigated the structural features of the fronds of three fern taxa of Rajasthan namely AmelopteriS prolifera, DiyopteriS cochuleata and with special reference to placement and pauern of leaf Araistegia pseudocystopteris venation. Loyal (1991) was the view that all the species of ThelypteridaCe ae in 31, 34, 35 64

and 36 chromosomal lines show free and pinnate venation in himalayan species. Britto et al., (1994) studied the venation pattern in Thelypteriod ferns of the Western Ghats of South India. In this mainly three types of venation pattern were seen namely open pinnate, semi reticulate and reticulate type. Anastomosis of veins is an advanced character. 5.2.2 Stomata Stomata have long been an object of study for morphologists,, aflatomtsts and Physiologists. In recent years the structure and pattern of stomata in ferns have generated renewed interest in Phylogenetic relationships among members of the Filicopsida. All the same no attempt has so far been made to determine the detailed types of stomata in Pteridaceae members of South India. lnspite of several contributions on the stomata of Indian ferns (Nayar, 1961 a, b,c; 1963 a, b; Nayar and Chandra, 1965; Pant, 1965: Pant and Kid wal, 1968 ; Pant and Khare, 1969, 1972 ; lnamdar, 1970 ; Inamdar et al., 1971; Paliwal et al., 1972; Rao, 1973; Chandra and Hashim, 1974; Patel et al., 1975; Bir and Trikha, 1979) by and large, survey of stomatal patterns in majority of the Indian fern species has not been made so far. In general, only a little is known about the distribution of various morphological types of mature stomata in ferns. Vesque (1889) was the first person to classify different stomatal types. The developmental pattern of the stomatal apparatus shows absolute constancy in the majority of families. One can easily define the ontogeny by studying the structure of adult stomata. Vesque distinguished four major stomatal types which he named after the families. It is most important to note that Vesque did not accept the possibility of attributing a certain taxonomical value to the stomatal types, since identical types occur in very distantly r elated families. In his view the form of stoma in transverse section is an important character for taxonomic conclusions. Less valuable are the number of stomata, their distribution, their position with respect to the level of the epidermis and their dimensions and shape. 65

Metcalf and Chalk (1950) recognised five types of stomata such as anomocytc, anisocytic, paracytic, diacytic and actinocytic. These new terms are now generally used to describe the stomatal types. Kondo (1962) worked only with the ferns and classified ontogenetic stomatal patterns by the number of cell divisions necessary to produce the mature stomata and the relative position of the guard cells to the neighbouring and subsidiary cells. He made an extensive study of stomata in 450 species of ferns belonging to 101 genera and described 10 stomatal types. Thurston (1969) visualised the developmental patterns of stomata in four major fern groups such as DicksofliaCeae, Pteridaceae and DennstaeditiaCeae and Cyatheaceae and pointed out their taxonomic significance. Van cotthum (1970 a, b) named five new topographic types in addition to those already known based on a study of 510 species of ferns namely hypocytic, pericytic, desmocytic, polocytic and staurocytic. Four of these, excepting the last, had already been described by previous workers but under different names. In all, he found different types f stomata in f&:ns and he brought to bear the results of his investigations on the system of classification proposed by Copeland (1947) and others. Bir and Trikha (1979) studied the stomatal patterns in 40 spec i es of Polypodiaceous ferns from Himalayas. Comparison of stomatal types of taxa belonging to Pyrrosia, Lepisorus and PhymatoPteriS along with Phymatosome s and their relationship were also studied by them. They concluded that the relevance of stomatal pattern for taxonomic differenciation was at inter and intraspecific levels. They have also cautioned that there should be consistency about the use of any single stomatal classification. They have also stressed that stomatal pattern studies have limited scope in fern taxonomy but this character has been exceedingly useful in broad segregation of various groups of ferns. Bir et al., (1980) studied the stomatal patterns in certain Athyriod ferns from India and summarized that stomatal pattern, frequency, size and index are helpful in the distinction of closely allied species and different intraspecific cytotypes. al., (1981,1983) studied the stomatal patterns in some Asplenoid ferns from Bir et India. In these stomata are mostly polocytic and anomocytic excep t for A. s!mosiaflum

where there are diacytic and hexacyclic. In addition to this, occurrence of two additional types of stomata as anisocytic (Asplenium auritum) and diacytic (A.nidus ; A.phyllitidis) is noticed in Indian members. They concluded that the usefulness of stomatal patterns is of limited value in segregation of closely allied taxonomic identities. However, stomatal characteristics may play an important role when taken in to consideration in conjunction with other taxonomic characters. Sen and Hennipman (1981) studied the stomatal structure andontogeny of Polypodiaceous members. A number of different new stomatal types were recognised, described and their ontogeny investigated. The different types of stomata were discussed in relation to their possible significance for tracing phylogenetic relationships in the family following a cladistic analysis. In conclusion, the analysis of the stomatal types in a large number of taxa of polypodiaceae, together with a study of the ontogeny of a selection of polypodioid species, gives a strong evidence for the recognition of a number of possible natural groups. Mehra and Soni (1983) studied the stomatal patterns in 358 species belonging to 117 genera in Pteridophytes. They concluded that the Psilophytaceous stomatal pattern was basic and all the others have been derived along a plurality of lines in the Pteridophyta. Sen (1986) investigated the structure and ontogeny of stomata occurring on the fronds of Davallia and allied genera. Of the nine types of stomata recorded, seven are new reports for these ferns. Stomatal structure supports Holttum's scheme, in which Rumohra (Placed in Aspidiaceae by Copeland) is associated with Davallia and also his separation of the genera Nephrolepis, Oleandra, Arthropteris and PsammiosomS as a distinct group: among the latter, Nephrolepis rather than Oleandra is shown to be peculiar. Sen and De (1992) studied the structure and ontogeny of stomata in ferns on the basis of ontogeny and arrangement of the surrounding cells. The stomata in ferns are classified into twenty four types. The ontogenic interrelationship among different stomatal types were traced and the role of stoma in determining the taxonomic position of Psilotum tmesipteris and the Ophioglossum group of genera were discussed. It is concluded that the mesogenous 67

and mesoperigenous types of stomata are not distinct entities-one is the derived form of the other. The polocytic stoma which is mesoperigenous in origin is however, not accepted as the direct descendent of the anomocytic (Perigenous) type. 5.2.3 Spore Morphology Fern spores have actually been objects of study for well over a century but only in the past quarter of a century the spores of ferns have been used extensively in elucidating systematic relationships. Studies of spores of ferns were made in the late nineties by Fischer Von Waldheim (1864), and Fischer (1892). C.B. Weaver in 1896 studied the spores of f3ms followed by Mcvaugh who in 1935 made a similar study of ferns of north eastern United States. In other parts of the world much work has been done by many scientists as for example, Knox (1951) involving British ferns, Sladkov (1 959a, 1959b, 1961) on Russian ferns and Sorsa (1964) on Scandinavian ferns. Tardieu Blot's reports (1964, 1965, 1966) on the spores of Madagascar fern are notable especially for the illustrations. A systematic study of fern spore morphology in India was initiated by schools of Nayar and Bir(Nayar, 1962, 1964, 1969, 1974, 1978; Nayar and Devi, 1963, 1964a, 1964b, 1964c, 1965, 1966, 1967, 1968a, 1968b; Nayar and Kaur 1963, 1965; Devi, 1966, 1977, 1981; Bir, 1976, 1980, 1983; Bir and Trikha, 1980). They concentrated mostly on the North Indian materials. Spore ornamentation of Japanese species of Di'yopteris and a comparative study of the morphology of perispores by SEM in forty species belonging to the genus Polystichum were studied by Mitui (1972, 1973). Goswami and Khandelwal (1973) and Pant and Misra (1975) have demonstrated assessable differences in spore morphology and stressed their importance in the diagnosis of species of Ophioglossum. Khandelwal (1987) also studied the importance of the fine structure of the spores of 11 species of the genus Ophioglossum. An extensive study of the spore morphology of Athyriod fern Cystopteris was carried out by Alston (1951), Wiggins (1954), Wagner (1955), Hagenah (1961), Blasdell (1963), 68

Jermy and Harper (1971), Bir and Trikha (1973) and Devi (1977). All these works indicate the usefulness of spore characters in the segregation of various species of the genus Cyptopteris. Spore morphology of 31 species belonging to 14 genera included by Pichi Sermolli (1977) in Dennstaedtiaceae and Hypolepidaceae was examined under LM and SEM by ChattopadhYaY and Sen (1992). They concluded that the spore morphcogy support the institution of two families to accomodate the species investigated. Cit.SS not Usha Bajpai and Hari Maheswari (1986) studied the surface ornamentation and fine structure of megaspore sporoderm under SEM in five species of se/ag/ne/ia. Kabir and Sen (1989) described the structure of spores of seventeen species of Pteris from India. The spores of all the taxa are quite similar, being trilete interestingly. The formation of monolete spores by reducing the arms of the trilete mark suggests that the genus is probably in the active state of evolution. Lee et al., (1990) investigated the relationship of 11 genera, 15 species and I variety in the Korean Pteridaceae. On the basis of spore shape, surface ornamentation and absence or presence of penine the species were divided into 4 groups. Spore morphology along with sporoderm characteristics of 22 species of Adiantum from different Asian countries have been studied by BhattacharYYa and MukhopadhYaY (1992) LM and SEM. Sharma (1992) reported the ontogeny of sporangiun and sporogeflesis using in six species of Ophiog!OSSUm from Rajasthan. Tuhinseri Sen (1993) reported the ultra structural properties of the spores of fern genera Leucostegia araiostegia and Scyphularia in detail for the first time and the ontogeny of the spore wall of these plants was traced as far as possible. MadhusoOdaflan and Jyothi (1993) reported the relation between palynology and taxonomy based on their studies on South Indian CheilanthOid ferns. Bhavanafldafl and Sankariammal(199 3 ) also studied th spore morphology of 14 species under 8 genera belonging to the family Aspidiaceae. They concluded that the spores are monolete bilateral. Recently Britto et al., (1996) studied the scanning electron microscopic observation of spores of Thelypteniod ferns of the Western Chats - South India. They reported that spores

of these ferns resembles those of the Aspidiaceae in being bilateral and having a distinct perine. Rolled et al., (1996) carried out the SEM studies on the spores of three taxa of Chistenseflia and reported the spores differ in shape, size and exospore characters such as spine distance, length, curvature, banding, apex morphology and fusion which are taxonomically significant. 5.3 MATERIALS AND METHODS 5.3.1 Venation Venation was studied by vein clearing method (Gourley, 1930). For this Pinnae were kept in 4% KOH solution with few drops of Basic Fuschin in an oven at 60 C over night. KOH solution makes the plant tissue very soft. Hence after clearing, care was taken in handling the materials. It was washed in tap water till there was no trace of KOH. Basic Fuschin imparted a purple colourto the veins and were hand drawn using LABO Stereo Microscope. 5.3.2 Stomata The materials for the present investigation were collected from the herbarium specimens obtained from St.Xaiver'S College Herbarium (XCH), St.Xavier's College, Palayamkottai. Information about the presently used material is given in Table -1 Chapter 1. A portion of the fully developed lamina taken from dry herbarium specimen was boiled in water for 15 min so as to soften it. This specimen was later boiled in 10% potassium hydroxide solutior for 3-5 mm. After thorough washing in water, the upper and lower epidermal peels were taken off. These epidermal peels were stained with 1% aquous safranin and mounted in 50% glycerol. For average size of the stomata, stomatal index and stomatal frequency/mm 2, average surements/c0unt111g5 were taken after random sampling. For stomatal index of 10 the following formula was applied. 70

Stomatal Index = Number of stomata per unit area X 100 Number of stomata + Number of epidermal cells per unit area per unit area The diagrams are drawn to scale using camera lucida and size reduced accordingly. The data pertaining to the present study have been presented according to the plan Van Cotthem (1 970a) and Sen and De (1992) for comparative purpose. 5.3.3 Spore Morphology The spore samples collected from the herbarium specimens at St. Xavier's College Harbarium (XCH), Palayamkottai. Herbarium specimens were critically studied and properly identified for the present study. The characters of the spores were studied under light microscope (LM) (Trinocular research microscope, LABO, India). The size of the spores were measured by light microscope and the mean value of the size of each spore was taken. For SEM studies the spores were sputtered with 3 mm platinum at 110 C for 5 mm. After sputtering, the spores were transferred to the HITACHI S-900 Scanning Electron Microscopy, ETH, Zurich, Switzerland and Photos were taken with an accieration of 60-70 K V at -165 C. 71

5.4 OBSERVATION AND DISCUSSION 5.4.1 Venation Pattern (a) Pteris vittata L. Veins are very slightly distinct above and below, spreading and usually forked once, rarely unforked or forked twice. There are 20 secondary veins in 1 cm length, completely free (Fig.la). (b) Pteris multiaurita Ag. Veins are slightly distinct above and well distinct below, pinnate and slightly ascending. All the veins are forked once or twice. If forking is twice, both the daughter veins forked for a second time. There are 15 veins per cm length (Fig.1 b). (c) Pteris pellucida Presl. Veins are distinct above and below; Pinnate free, parallel, more or less perpendicular to the midrib in larger leaves and slightly ascending in maller leaves. Veins are simple or forked once, forking may be at any place. There are 20-24 veins per cm length; veins are reaching the margin. (Fig.lc) (d) Pteris cretica L. Veins are forked once, free, reaching the margin. Veins are distinct above and below. Simply pinnate, there are about 14-16 veins per cm length more or less perpendicular to the costa (Fig.ld). (e) Pteris scabripes Wall. ex Ag. Veins are hardly distinct above, slightly distinct below; Pinnate free, simple or forked or forked once, reaching the margin There are 14 veins per cm length, more or perpendicular to the costa (Fig -2a). 72

Pteris vittat a Al Pteris multiaurita a Pteris pellucida Pteris cretica FIG. 1

(f) Pteris Ion gipes D. Don Veins are slightly distinct above and below, ascending, forked once, reaching the margin. There are 13 veins per cm length, no veins are coming from the costa; basal veins are reaching well above the base of the sinus (Fig.2b). (g)pteris biaurita L. Veins are well distinct below and slightly distinct above. Costules are slightly raised below. Veinlets are pinnate on the ultimated lobes, commonly forked once, rarely forked twice and simple; if so usually the acroscopic one is forked, the vein lets are remn simple. Intercostular distance are 5-9 mm. Ultimate veinlets are 14-16 per cm length and reaching the margin of the lobes. They are slightly ascending but parallel. Veinlets are not originated from the main costa other than the costule and the costal arch ends (Fig.2c). Costal arch In P.biaurita the lobing of pinna is upto 2-4 mm to the costa resulting in 2-4 mm continuous ring along the costa. If the basal most veins of the adjacent costa reach the sinus base independently there will be a triangular leaf blade surface without the supply of any vascular tissues. Possible way for the vascular supply is origin of veins directly from the costa and reaching the base or side of the sinus independently, but in this species costal arch is formed. 4-6 veinlets arise from the outerside of the costal arch and then reach the side or base of the sinus. The arch may run from one costule to the other or it may arise from the costule and ends well below the next costule. This type of anastomosing of the basalmost veins from the adjacent lobe is common in a Thelypteroid fern Christella in which 1-2 pairs of basal veins from the adjacent lobes anastomose to form an excurrent vein reaching the base of the sinus. Walker (1962) correlated the mode of costal arching and the ploidal level in P.biaurita. According to him in triploid apogamous, the costal arch runs from one costule to another costule while in the diploid apogamous taxa it does not run from one costule to another costule.

Pteris scabripes Pteris Ion gipes Pteris biaurita Pteris kleiniana C FIG.2

(h) Pteris kleiniana Christ. Veins are distinet above and below, slightly ascending. All the veins except few pairs at the apex are forked once, not reaching the margin, ending with a Iiydathode submarginally. Atleast in the basal 50% of the pinna lobes, the basal most veins of adjacent lobes join to form a short excurrent vein reaching the base of the sinus. Six primary veins are present per cm length (Fig -2d). (I) Pteris aspericaulis Wall. ex Ag. Veins slightly distinct above and below, slightly ascending, forked once, reaching the margin, basiscopic, basal vein arise from the costa; basal vein reaching well above the base of the sinus. 12-13 veins per cm length; costa, costules and veins are pinkish in colour ( Fig-3-a) (J) Pteris mertensoides Willd. Veins are slightly distinct above and below, open pinnate and slightly ascending. All the veins except few at the apex of the lobes are forked once; frequently the acroscopic veinlet, rarely the basiscopic veinlet forked second time. Veins are reaching the margin, 12-15 veins are per cm length. Intercostular distance is 7mm (Fig.3b). (k) Pteris otaria Beddome. Veins are slightly distinct above and below and slightly ascending. Veins are forked once or twice reaching the margin. Origin of veins from the costa is common. Basal veins reach the side of the sinus base. There are 12-14 veins per cm length (Fig.3c). (I) Pteris argyraea T. Moore Costules are slighity raised below; intercostular distance is 5-7 mm; veinlets are slighity ascending, parallel, 12-14 per cm length and also reaching the ma'. 74

Pteris asperica u/is Pteris otaria Pteris mertensiodes Pteris argyraea

are usually forked once, rarely forked twice; forking is usually very near to the costa, rarely 2-3 mm away from the costule. Usually the veins in the lobes are anadromous. The acroscopic vein arises from the axis of the costa and costule while the basiscopic vein arise from the costa well below the costule. The basal veinlets of the adjacent lobe reach the base of the sinus independently (Fig.3d). (m) Pteris un earls Poi r. Veins are well distinct above and below and slightly raised above and below. Open pinnate, completely free and slightly ascending. Except the few veins at the apex of the lobe, all the veins are forked once, reaching the margin. Basal acroscopic vein arises from the axis of the costule and costa while the basal basiscopic vein arises from the costa, basalmost veins of the adjacent lobes reach the base of the sinus. 10-12 veins are present per cm length (Fig.4a). (n) Pteris con fusa T. G. Walker Veins are slightly distinct above and below, very slightly ascending. Veins are forked once or twice reaching the margin, completely free, 13 secondary veins are per cm length. Basal veins of the adjacent lobes meeting at the base of sinus without joining or reaching the side of the sinus. IntercostUlar distance is 8-10 mm (Fig.4b). (o) AcrostichUm aureum L. Veins are slighlty distinct below but indistinct above. Veins are anastomosing to form a long elongated parallel areoles of 1/2 mm diameter, approximately 2-5 mm long without included veinlet. Series of areoles are approximately 450 to the midrib, free ends of the veins of the border reaching the margin (Fig.4c). 75

Pteris I/n earls Acrostichum aureum oil Pteris confusa

KEY TO THE SPECIES OF SOUTH INDIAN SPECIES OF PTERIS 1. Ultimate veins originate directly from the midrib or costa of the leaf pellucida 2. Individual veins upto 7-12 mm long - 2. Individual vein upto 8 mm long 3. Veins more or less perpendicular to the midrib 4. Veins well distinct on the leaf surfaces 5. Secondary veins per cm length are 15 - cretica 5. Secondary veins per cm length are 20 - vittata 4. Veins slightly distinct on the leaf surface - scabripes 3. Veins slightly ascending (Ca. 450 to the midrib) - mu!tiaurita 1. Ultimate veins originate from the costules 6. Basal veins of the adjacent lobes join to form an excurrent vein 7. Veins not reaching the margin; ending submarginally with a k!einiana hydathode - 7.Veins reaching the margin - biaurita 6. Basal veins of the adjacent lobes reaching the base or side of the sinus independently 8.Veins and costa carmine red - aspericau!is 8. Veins and costa yellowish green or stramineous 9. Veins well raised above and below when drying - linearis 9. Veins not raised above and below when drying 10. Midrib (costa) bear about 2 mm long slender spinules - Ion gipes 10. Midrib (costa) free from spinules or bearing less than 1 mm long spinules 11. Costa free from spinules - mertensiodes 11. Costa (and costules in some case) bear (5) spinules 12. Both costa and costules bear 0.9-1 mm long spinules - otaria 12. Spinules on costa only 13. Inter costular distance 5-7 mm - argyraea 13. Inter costular distance 8-10mm- confusa 76

DISCUSSION Mainly two types of venation are encountered within South Indian Pter;dQid 1ers. Open pinnate and reticulate. Veins usually are forked once and free, reaching the margin. Among the 15 species of the family Pteridaceae five species (Pteris vittata, P. multiaurita, P.pellucida, P.cretica and P.scabripes) are simply pinnate and in these the veins oriçirte from the midrib (costa) are forked once, free and reaching the margin (Fig.1,1b, 1 and 2a), whereas in Acrostichum aureum the frond is simply pinnate with reticulate venation (Fig.4c) Veins are copiously anastomosing to form series of areoles to'the costa, areoles free from any included veinlets. In P.Iongipes, P.biaurita, P. kleiniana, P.argyraea, P.confusa and P.Iinearis the fronds are simply bipinnate or ternately divided and bipinnate (Fig.2b,2c, 2d,3d, 4a, 4b). The Ultimate veins originate from the costules. The basal veins are anastomosing to form a series of areoles along the costa in the case of P.biaurita and P. kleiniana whereas in all other species basal veins are not anastomosing. P.biaurita is highly variable in the pattern of anastomosing of veins. According to T.G. Walker (Per. Commn. to Dr. V. S.Manickam) in Sri Lanka triploid, plants are with arch which extends from one costule to another while in diploid plants the arch does not extend from one costule to another (Fig.2c). In P.kleiniana thr. mode of anastomosing of basal veinlets varies greatly even within a pinna. In some cases, the basal veinlets just meet or do not meet at the base of the sinus. In some other cases the basal veinlets join to form a short excurrent vein reaching the base of the sinus or the archs bear two or four veinlets which reach the base or side of the sinus. Rarely, the veinlets join to form an areole just after forking especially at the base of the pinnate. Joining of adjacent veinlets on the same side is not uncommon. Usually, the arch does not extend from one costule to another since the basal basiscopic vein originates from the costa and not from the costule. 77

In several cases, particularly in the species Pteris quadriaurita complex the costa or costules bear short or long spinnules upto 2 mm long. Spinules are- present on the costa, while short (less than 1 mm), spinules are present in the costa of P.argyraea and P. con fusa. In P. otaria both costa and costules bear short spinules. In bipinnate species the veins are usually anadromous. Majority of the species of Pteris are with open pinnate, free venation. On some cases (P.biaurita, and P.k!einiana), the basal veins of the adjacent lobes join to form a costal areole. In general, the venation pattern of the Pteris species are helpful in delimiting atleast the distantly related taxa. With careful analysis of the venation pattern of the South Indian Pteris species, a key has been prepared to identify the species from South India by using vein characters only. From the present investigation it is concluded that usually free veined species are growing at higher altitude in contrast to species with anastomosing venation. 5.4.2 STOMATA The present studies on the South Indian representation of the ferns of the family Pteridaceae are in the direction of a survey of stomatal types, stomatal frequency, stomatal index and size of the 15 species belonging two genera namely Pteris L. (14 species) and Acrostichum L. (One species). In all the species studied, the stomata are always present on the lower surface i.e., exhibiting hypostomatic condition. Stomata are distributed over the entire expanded lamina surface except over the veins, Information about the stomatal patterns occuring in fully developed lamina of 15 species of the family Pteridaceae is reproduced in the Table 1, which also included data on stomatal index and stomatal frequency (mm'), stomatal guard cell size. Here, stomatal types and sub-types are recognised on the basis of classification of Van Cotthem (1970 a). Among the fifteen species of the family Pteridaceae, the stomata are of Polocytic type. Within this polocytic group the sub-types are parietocytic, axillocytic and coparietocytic. 78

0 Cl) 0 C) C) C) -.. C) 0 0 0 ci 0 0 0 0 0 0 0 0 0 0 m 0 Cd ( cl m 0 Cd cl c c CK3 c c U Cl, E 0 CID C) C) C) C) C) C.) C.) C) C) C) C) C.) C) C) C).-...... -.....-. >. ;. -' >. >. ;C >. r' C) 0 ci 0 ci 0 0 0 0 0 C) C) 0 0 C) 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0-0 0 0 0 - - 71 C x x x x x x x x x x x X x >< Cl ON 0. N '0 N N N N N N N N SD N 00 N t- 00 00 m '0 O N N 00 O '0 CN ti. kn 0 00 V '0 0 00 N N 0 0 00 0 N - rn cl rn O 00 CC 00 N C\ '0 m N 00 m m N N N r1 N r) C (ID ci cl tj 0 E- - - o?, qj'- Qj ci Ll C zi rj)

cell usually has a U or horse shoe - shape. The link is always situated at the distal end of the guard cells and never lower than halfway along the guard cells (Fig.1-4). In the parietocytic sub-type the stoma in a parietal position is attached to one lateral wall at the distal, margiflopolar end of the single subsidiary cell (Fig-la, b, c; Fig.2 a, c, d; Fig.3 a, d; Fig.4 a, b, c) but in axillocytic sub-type the stoma in an axillary position is attached to two lato r al w' at the distal, margino polar end of the single subsidiary cell (Fig.2 b; Fig. 3 b). In coparietocytic sub-type stoma of the ParietocYtiC sub-type is accompanied by a second subsidiary cell at the proximal centropolar end (Fig.1 d; Fig.3 c). Among the 15 species studied Pteris vittata, P. Ion gipes and P. peliucida are sexual tetraploids whereas P. multiaurita, P. scabribes and AcrostiChUm aureum are sexual diploids. Pteris cretica, P. biaurita, P. aspericaulls, P. argyraea, P. con fusa and P. otaria are apogamous diploid, triploid and tetraploid respectively (Walker, 1962). So far nobody has worked out the cytology of the species namely P. kleiniana, P. meensi0des and P. /inearis because these are very rare species. The first evidence of a relation between cell size and polyploidy in the ferns was Lawton'S 1932 demonstratio n on stomates in induced apogamous races of DtyopteriS margiflalis and Woodwardia virginica vary directly with ploidy level. The stomatal guard cell size of the selected PteriS species ranges from 16.5 X I O.5m to 29.1 X 22.7 l jm. The maximum size was seen in PteriS longipes whereas the minimum Size of the stomatal guard cell generally depends on ploidy size was noticed in P. multiaurita. level (Wagner, 1954; Louis and ReichSteifl, 1968; Schneller, 1974; Barrington et al., 1986). If it is sexual there is a clear cut difference between the lower and higher ploidy level but in apogamous there is no such difference in the ploidy level. species can be divided into three complexes namely The selected Pteris PteriS multiaurita, P. Ion gipes, P. aspericaulis P. con fusa, Pteris quadriaurita complex ( complex (Pteris peiiucida P. cretica, P. linearis, P. otaria P. argyraea)1 Pteris scabripes P. scabripes) and PteriS biaurita complex (PteriS k!einiana, P. biaurita). Apart from these are treated separately. some species (PteriS mertensiodes, P. vittata, AcroStiChum auroum) 79

D Fig.1 A. Pteris argyraea T. Moore C. Pteris vittata L. B. Pteris con fusa T.G. Walker D. Pteris kleiniana Christ.

I / A ma A. Pteris pellucida Presi. B. Pteris scabripes Wall. ex Ag. C Fig.2 C. Pteris mertensiodes Wilid D. Pteris otaria Beddome LN

ON C ED A. Pteris aspericaulis Wall. ex Ag. B. Pteris cretica L. Fig.3 C. Pteris Ion gipes D. Don D. Pteris linearis Pair.

am C Fig.4 A. Pteris vittata L. B. Pteris Pteris muitlaurita Ag. C. Acrostichum auroum L.

The stomatal guard cell size in sexual cytotypes is more or less constant in contrast to apogamous cytotypes in which the guard cell size is highly variable. (Barrington et al., 1986). In Pteris quadriaurita complex two species namely Pteris multiaurita, Pteris longipes are the only two sexual cytotypes - diploid and tetraploid. Due to ploidal level there a vast difference between the two cytotypes (16.5 X 10.5; 29.1 X 22.7) Since Pteris quadriaurita Retz. sensu stricto has most likely become extinct in South India,. it is not possible to compare the guard cell size in the various species of this complex. Pteris scabripes complex namely P. pellucida, P. cretica and P. scabripes are morphologically closely related with simply pinnate lamina. Among the above three species, there is a considerable difference in the stomatal guard cell size due to ploidal level. P. pellucida 4x (32 X 16); P. scabripes 2 x (19 x 12). But in triploid apogameus P. cretica the guard cell size is more or less closely related to sexual tetraploid of P. pellucida (Apogamous - triploid spores are abortive). P. otaria is a hybrid between two diploidal sexual parents P. multiaurita and P. quadriaurita ( Walker, 1958). In this case the stomatal guard cell si.- 7 3 is kiçjer than the parental one. In P. quadriaurita complex there are 3 apogamous species (2 diploid, one triploid). Comparatively in P.aspericaulis triploid apogamous species the stomatal guard cel l e is larger than the other two diploid apogamous. From this observation there is a clear-cut difference between different sexual cytotypes of apogamous taxa belonging to the same or related species where the stomatal guard cell size shows continuous variation. 80

Plate - I Plate and Fig No a b C d e f Name of the Species Pteris vittata L. Pteris multiaurita Ag.. Pteris peilucida Presi. Pteris cretica L. Pteris scabripes Wall. ex Ag. Pteris Ion gipes D. Don Magnification 2000X 1500X 1500X 1500 X 1500X 1500 X

r L^ d Wa -. : / A ḇ --A - llq 'VtW Plate:I

5.4.3 Spore Morphology (a) Pteris vittata L. (Plate I-a) Spore shows the distal view. Spores 40 X 52 tm in size. Exine yellowish green with tangled thread like thickenings. Exine tuberculate to regulose on the proxrnal se and reticulate on distal side. Reticulate surface non-perinate. (b) Pteris mu!tiaurita Ag. (Plate I-b) Spore shows the polar view. Spores 35 X 30 1tm in size. Amb. triangular having rounded corners. Spores with granulate surface. Trilete broad in size. Equatorial collar slightly interrupted with undulated crest. (c) Pteris pellucida Presi. (Plate I-c) Spores 40 X 50 im in size. Exine light yellowish brown, regulose to nearly spinose. Gradual reduction in size of the regular from distal to Proximal pole. The regulae on the distal surface are smaller and more spine like towards he equator - those on the proximal surface often verruca like. Equatorial collar uninterrupted. Collar separating the two phases. Tubercles are round in shape. (d) Pteris cretica L. (PlateI-d) Spore shows the distal view. Spores 32 X 43 im in size. Amb triangular. Exine golden brown, regulose with regulae on the distal surface, not crowded, irregular and some time s tubercle like. Equatorial collar partially interrupted with prominently undulated crest and with irregular sides. Large islands on the proximal side connected to the inner collar, outer verrucate. 81

Plate - II Plate and Name of the Species Magnification Fig No a Pteris biaurita L. 2000 X b Pteris kleiniana Christ. 1500X c Pteris aspericaulis Wall. ex Ag. 1500X d Pteris mertensiodes Wilid. 2000X e Pteris otaria Beddome 2000X f Pteris argyraea T. Moore 2000 X

ale C) ee^ I^w S---

(e) Pteris scabripes Wall. ex Ag. (Plate I-e) Spore shows the distal view. Spores 40 X 56 j.im in size. Amb triangular. Exine golden brown, densely regulose on the distal and verrucate on the proximal side. Distal surface tuberculate with fringed margins. Outer ones are connected with each other whereas inner ones free. (1) Pteris longipes D. Don. (Plate I-f) Spore shows the distal view. Spores 44 X 36.tm in size. Amb. triangular with narrowly rounded corners. There is a central triangular region which demarkated by cap-like ridge all around. It extends into the proximal face and either divided or not divided. The general surface granulate and granules of various sizes. There is an outc- (ng possessing rounded projections (verrucate). Exine verrucate. Equatorial collar uninterrupted with smooth crest. (g) Pteris biaurita L. (Plate IT-a) The spore shows the distal view. Spores 40 X 54 im in size. Amb. triangular having narrowly rounded corners. Exine reddish brown, densely regulose on the distal surface and verrucate on the proximal surface. Equatorial collar uninterrupted, tuberculate, granulate around the apertural region. Isolatea granuiuz5 uuui uuit surface minutely granulate. Tubercles often fused or connate forming a larger or small ridges or other configurations. (h) Pteris kleiniana Christ. (Plate 11-b) The spore shows the lateral view. Spores 30 X28 m in size. There is a ring over the cap which separates the proximal and distal faces. General surface granulate Surface ridged. Ridges with various sizes and shapes. 82

Plate - III Plate and Name of the Species Magnification Fig No a Pterisiinearis Poir. 1500X b Pterisconfusa T. G. Walker 1500X c Acrostichum aureum L. 2000X

let 4 I I rp¼\ if' Plate:lll Cl

(I) Pteris aspericaulis Wall. ex Ag. (Plate li-c) The spore shows the polar view. Spores 49 X 76 min size. Amb. triangular. Spore is dark brown in colour. Exine pale reddish brown. Ridges on the distal surface whereas small verrucae on the proximal surface. Tubercles are interspersed with pebble like projections. Trilete are wavy. Equatorial collar uninterrupted with smooth crest and sides. (J) Pteris mertensioides WilId. (Plate II-d) The spore shows the proximal view. Spores 30 X 29 1im in size, dark brown in colour; Amb. triangular with rounded corners. Strong equatorial flange. Homotrite. Surface is tuberculate with various sizes and shapes. Tubercles are fused or not fused, outer surface is granulate. (k) Pteris otaria Beddome (Plate II-e) The spore shows the distal view. Spores 38 X 28 tm in size with narrow perispore. Amb. triangular. Exine with thin irregular reticulate furrowings. Spores have coarse tubercles and ridges with the equatorial ridges. General surface granulate. (I) Pteris argyraea T. Moore (Plate IT-f) The spore shows the proximal view. Spores 35 X 36 m in size with minutely reticulate exine. Amb. triangular. Spores with coarse tubercles, they ar more or less fu;u into ridges and spherical deposit. Tubercles are varying in size. The faces are unequal with the flange closer to the apex. Strong equatorial collar flange. (m) Pteris IineariS Poir. (Plate ITT-a) The spore shows the distal view. Spores 50 X 39 m in size. Spores are hemispherical in nature yellowish green colour with broad perispore. Exine is with thin reticulate. General surface is granulate. Granules are different in sizes. Aperture is trilete and also heterotrilete. the three dimensions of the spore wall are varied in length and width. All 83

(n) Pteris con fusa T. G. Walker (Plate 111-b) The spore shows the distal view. Spores 48 X 38 tm in size. Amb. triangular. Exine light and dark brown in colour. Spore surface regulose with the regulae on the distal face not crowded. Sometimes irregular and tubercle like structures are present on the spore surface. Equational collar partially interrupted with prominently undulated crest and irregular sides. (o) Acrostichum aureum L. (Plate 111-c) The spore shows the distal view. Spores 48 X 62 jtrn in size, trilete and oblique. Amb. triangular. Spores are slightly rough and have strands or rods mostly associat! with coarsely papillate structures. Exine is deep brown with granulae and sometimes with cracks. Acrostichum spores differ from spores of Pteris and respresent a discrete type among the Pteridoid ferns. DISCUSSION The spores of Pteridaceae are typical in being trilete, with a thick set regulose, tuberculate and possessing a prominent equatorial collar separating the proximal face from the distal face. There is a usual tendency for the outer ornamented layer of the exine. This layer has often been described as perine (Erdtman and Sorsa, 1971). As Devi (1977) reported SEM helped in getting a more magnified and closer look at the surface with an added depth of vision. The surface pattern of the Pteridoid spores are almost granular, tuberculate except in Pteris vittata i.e. reticulate. These figures have no correlation with the probable affinity of species speculated by the combination of other taxonomic characters. Although the surface pattern of spores is one of the diagnostk features to seize the Pteridoid as a whole, the spores hardly serve the purpose of the distinguishing the minor groups in the series of ferns. On the other hand Schraudoff (1984) reported that the prepattern of microtubule association in the tapetum provides the blue print for the design of the spore wall. According to him the exine morphology of spore is a stable character worthy of taxonomic considerations and hence is pro bably gene regulated. Sporophytic rathar than gametophytic genes determine the final form of exine. 84

The spores of the Pteridaceae members of the present investigation are closely related to the spores of Pityrogramma, Anogramma Onychium, and ActiniopteriS. This supports the suggestion that these genera, contrary to the usual concept (Copeland, 1947, Holttum, 1947, 1954; Ching 1940) are closely allied to Pteris ( Nayar, 1962a, 1964; Nayar and Devi 1968). From the above discussion that in Pteridoid ferns the spore characters can also be used as an important tool in taxonomy along with the other characters. 85

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