Proc. Indian Acad. Sci. (Plant Sci.), Vol. 99, No. 2, April 1989, pp. 131-134. Printed in India. Cytological observatŸ on some species of Pter… L. from Kumaon (northwest Himalaya) N PUNETHA and ABHA SEN Department of Botany, Government P G College, Pithoragarh 262 501, India MS received 4 January 1988; revised 20 January 1989 Abstrar The paper deals with the cytology of 10 taxa of 8 species of the genus Pteris L. from Kumaon in northwest Himalaya. Pteris biaurita and Pteris dactylina ate apogamous triploids (n=87), Pteris excelsa and Pteris quadriaurita are sexual diploids (n=29), whereas Pteris vittata is a sexual tetraploid (n = 58) and Pteris stenophylla is an apogamous diploid (n=58). Pteris cretica is represented by diploid (n=58) and triploid (n=87) apogamous races. Pteris wallichiana is normally sexual diploid (n = 29) but an apogamous diploid (n=58) form from this area is a new record. Sexual mode of reproduction is observed in 40% taxa whereas 60% are apogamous. Keywords. Apogamy;cytology; Pteris L. 1. Introduction Although there is considerable information on the cytology of eastern as well as western Himalayan ferns, the cytological studies on the western Himalayan ferns were mainly confined on the ferns of Simla and on Darjeeling and Sikkim Himalayan ferns of the eastern Himalaya. Within western Himalaya the fern vegetation is predominantly evergreen in the Kumaon region which apparently forms the easternmost limit of western Himalaya within Indian territory. Many ferns common in eastern Himalaya extend to the Kumaon region in north-west Himalaya. Besides being neglected taxonomically, the ferns of Kumaon were not examined cytologically earlier. Any information on the cytology of ferns of Kumaon is based only on the reports of workers dealing with the ferns of western Himalaya (see Mehra 1961; Bir 1973; Love et al 1977). While this region is very important from phytogeography point of view, the cytology of ferns of this region needs much attention as many cytotypes reported from eastern Himalaya are found in this area but they do not extend beyond Kumaon in the western Himalaya (N Punetha, unpublished results). Keeping this in view, the present studies on Kumaon ferns were taken up. Pteris L, is represented by about 280 species (Copeland 1947) which are fairly widespread in the tropical and sub-tropical parts of the world. About 12 species of this genus are found in the va¡ climates in Kumaon (Punetha 1986). In this study 8 species (10 taxa) of Pteris from Kumaon have been cytologically investigated. 2. Materials and methods Aceto-carmine smear preparations of young sori fixed in absolute alcohol, glacial acetic acid (3 : 1) were made by customary methods. Places of collection of different species are mentioned in table 1. Apogamous and sexual forms are determined mainly on the basis of number of spores per sporangium. Voucher specimens are preserved in the Pteridology laboratory, Department of Botany, Government P G College, Pithoragarh (Bot. Pithoragarh). 131 132 N Punetha and Abha Sen 3. Results The results listed in table I indicate that 2 species are sexual diploid, 3 species ate apogamous triploid, 1 species is sexual tetraploid and P. wallichiana is represented by sexual diploid and apogamous diploid cytotypes. Out of the investigated taxa 60% are apogamous and 40% ate sexual. P. biaurita L. is fairly common in Kumaon and grows in exposed as well as humid shady places. Formation of 32 spores per sporangium and n=87 is suggestive of its being a triploid apomict (figure 1). P. cretica L. is very variable in its leaf morphology. In Kumaon ir occurs both as diploid and triploid (n = 87, figure 2) apogamous races. In branching and shape of frond P. dactylina resembles P. cretica but ir differs in that the leaflets in P. dactylina are narrow and the stipe is wiry. As far as known the western Himalayan P. dactylina has not been examined cytologically earlier, it is known to be apogamous triploid in eastern Himalaya. In Kumaon region ir is common at many places in Pithoragarh district and is apogamous tfiploid (n = 87, figure 4). Another species which resembles P. cretica in external morphology is P. stenophylla. Relatively long, narrow leaflets and crisped margins in the latter easily distinguish it from the former. Cytological examination of this species proved it to be apogamous diploid (n = 58). P. excelsa is sexual diploid (n= 29, figure 5). Another species with varied leaf morphology is P. quadriaurita, ir is sexual tetraploid (n=58, figure 3). Sexual diploid race of P. wallichiana is fairly common in Kumaon (figure 6). During our investigations we observed that in one plant of this fern from near Leesa depote, Cheenr (in Tanakpur-Pithoragarh route), the spore mother cells (SMCs) had 58 regular bivatents (figure 7). Maj0rity of the investigated sporangia were 8 celled which produced 32 regular spores. Although 7 plump sporangia beafing 16 giant spores were deter no chromosome counts was possible in these sporangia. Table 1. Chromosome number, mode of reproduction and ploidy level in Pteris species from Kumaon. Chromosome Mode of Ploidy Place of Specimen examined Species number 'n' reproduction level eollection (Bot. Pithoragarh) P. biaurita Linn. 87 Apogamous Triploid Leesa depote 87206, 87207 1200 m (Pth) P. cretica Linn. 87 Apogamous Triploid Lachher 86584 1800 m (Pth) P. cretica Linn. 58 Apogamous Diploid Rai-Panda 87876 1600 m (Pth) P. dactylina Hook. 87 Apogamous Triploid Didihat 87284 1900 m (Pth) P. excelsa Gaud. 29 Sexual Diploid Lachher 87547 1800 na (Pth) P. quadriaurita Retz_ 29 Sexual Diploid Binsar 1900 m 87322, 87323 (Almora) P. stenophylla Wall. 58 Apogamous Diploid Satsiling 87459, 87460 1700 m (Pth) P. vittata Linn. 58 Sexual Tetraploid Bhowali 87318, 87319 1800 m (N. Tal) P. wallichiana Ag. 29 Sexual Diploid Dhaj 87659, 87660 2700 m (Pth) P. wallichiana Ag. 58 Apogamous Diploid Leesa depote 87212, 87213 1200 m (Pth) Cytolo~ical observations on some species of Pteris 133 Ÿ irt'tr~, ~,-wiŸ ~ lp I "*"*'~ ,3 Ltm, 2'V" 3 '*'3 ~ ,4Ltm, 4 r 5 "~ 6 "*'1' " 7~.,, 9 r ...w Figures 1-7. Explanatory diagrams of meiosis in spore mother cells in 7 species of Pteris. 1. P. biaurita, n=87 (triploid apogamous). 2. P. cretica, n=87 (triploid apogamous). 3. P. quadriaurita, n = 58 (diploid sexual). 4. P. dactylina, n = 87 (triploid apogamous). 5, P. excelsa, n= 7.9 (diploid sexual). 6. P. wallichiana, n=29 (diploid sexual). 7. P. wa/lichiana, n= 58 (diploid apogamous). Morphologically, the spores in a sporangium are all alike, no shrunken spores are seen. Surprisingly, no other plant of this species with 58 bivalents during meiosis from this locality was found. There are no striking morphological differences between sexual diploid and apogamous diploid forms except that the fronds in the latter are relatively small and the stipe is stramineous. As far as known there is no record of apogamy in P. wallichiana. 4. Discussion P. cretica is represented by diploid apogamous and triploid apogamous races and both the races are common in eastern as well as in the western Himalaya (Mehra and Verma 1960; Verma and Loyal 1960; Verma t961; Verma and Khullar 1965; Jha and Sinha 1987). P. dactylina is triploid apomict in Kumaon and so in the eastern Himalaya (Verma 1961). Among the leptosporangiate ferns, the species of Pteris exhibit a wide range of variability in ploidy levels and also the apogamous procreation of sporophytes is very common in these ferns (Manton 1950). However, there is no variability in the 134 N Punetha and Abha Sen basic chromosome number which is constantly n = 29. Among the Indian species of Pteris examined cytologically, P. vittata is known by as many as 5 cytotypes (Mehra and Verma 1960; Verma 1961; Abraham et al 1962; Kuriachan 1978; Khare and Kaur 1983) but no apogamy has been reported in this fern in nature. In Kumaon it is sexual tetraploid. Triploid apogamous plants Of P. biaurita are known to be common in eastern and western Himalaya (Verma 1961; Ghatak 1962) but in south India it is diploid apogamous (Abraham et al 1962). P. wallichiana is so far known by only sexual diploid plants (Mehra 1961), the present investigation indicates that in addition to sexual diploid plants it is also represented by apogamous forms with n = 58. Although few sporangia with 16 giant spores were found, majority of the sporangia produced 32 spores. Half the usual number of spores per sporangium and twice the usual number of chromosomes in SMCs during meiosis are the concomitant characters of apogamous ferns. Although apogamy is said to be associated with hybridity (Manton 1950) and is known to be innate (Verma and Khutlar 1965), ir is difficult to speculate that the P. wallichiana apomict is of hybrid origin. Because the majority of the population of P. watlichiana is sexual diploid and just one plant is apogamous diploid, its ofigin by mutation seems to be most probable. This is also supported by the fact that the apomict, in all respect, is similar to the sexual diploid race. Acknowledgements Authors are thankful to the Council of Scientific and Industrial Research, New Delhi for financial help and to the Principal, Govemment P G College, Pithoragarh for facilities. References Abraham A, Ninan C A and Mathew P M 1962 Studies on the cytology and phylogeny of the Pte¡ VIL Observations on one hundred species of South Indian Ferns; J. lndian Bor Soc. 41 339-421 Bir S S 1973 Cytology of Indian Pte¡ in Glimpses in plant research (ed.) P K K Na.ir (New Delhi: Today and Tomorrow's Printers and Publishers) pp 28-119 Copeland E B 1947 Genera Filicum (Waltham: Chroniea Botanica Publication) Ghatak J 1962 Observation on the cytology and taxonomy of some ferns from India; Nucleus 5 95-114 Jha J and Sinha B M B 1987 Cytomorphological variability in apogamous populations of P.