The Journal of the Indian Botanical Society

Vol. XLVII 1968 Nos. 1-2

STUDIES IN THE FAMILY IN EASTERN INDIA: DISTRIBUTION AND ECOLOGY*

By G. P a n ig r a h i a n d S. N. P a t n a ik J

Botanical Survey of India, Allahabad

(Received for publication on May 28, 1966)

D istribution

Bedek)ME (1883, 1892) reported the occurrence of 78 species of the family Polypodiaceae (sensu Copeland, 1947) within the limits of poli­ tical India of today. Later, Hope (1899-1904), Fischer (1938), Mehra (1939) and other workers on Indian listed 26 additional species. The recent collections from Eastern India by the authors together with the study of literature have added 11 more species and 1 variety to the list, revealing the occurrence of 116 taxa of the family in India. Of these, 99 species occur in Eastern India (which is incidentally the richest in the flora in the whole country), 36 species in Northern India (mostly confined to the Western Himalayas) and 12 species in South India. Whereas genera like Polypodium, and Arthro- meris well represented in Eastern India are absent in South India, 9 species, viz., Pyrrosia angustata (Sw.) Ching, P. gardneri (Mett.) Sledge, P. longifolia (Burm.) Morton, P. stigmosa (Sw.) Ching, Crypsinus m ontam s Sledge, Grammitis attemata Kze., Prosaptia alata (Bl.) Christ., P. contigua (Forst f.) Presl and P. obliquata (Bl.) Mett. are restricted to South India.

Pyrrosia (20 spp.), Pleopeltls (17 spp.), Microsorium (13 spp.), Crypsinus (9 spp.) and Polypodium (8 spp.) are the dominant genera with larger number of species having comparatively wider distribu- •on) in contrast to the monotypic genera Dipteris, Christiopteris, Yiphopteris,- Platycerium, Grammitis and Aglaomorpha. Although

* Part of a thesis submitted by the Junior Author while working under the supervision and guidance of the Senior author at Shillong, Assam, between 1960-62 and approved for the Ph.D. degree of the Utkal University, Orissa, in 1965.

t Present Address: Lecturer in Botaiiy, Gov. College, Baubanesbwar, Orissa. seven species, viz., Dipteris wallichii. Polypodium atkinsoni, Pyrrosia mannii, P. stenophylla, P. subvelutina, Leptochilus minutulus, Thayeria sp. (= Drynaria meeboldii Ros.) are endemics to Assam and the Eastern Himalayas, none of the 12 South Indian species appears endemic to the region. Of the seven endemics, D. wallichii may be considered as a relict species, whereas the others (belonging to the more advanced genera with wider distribution) may be considered neo-endemics with potentialities for wider spread.

The subtropical forests are the richest in India (with 15 genera and 69 spp.) in number of genera and species and are followed by the tropical forests (11 genera and 42 spp.) and the temperate forests (9 genera and 24 spp.). The family is practically unrepresented in the subalpine Himalayas {Pleopeltis excavata var, scolopendria and P. loriformis have once been collected by the Eastern Circle of the Bota­ nical Survey of India, from this region). Dipteris and Drymoglossum are restricted to the tropics, Neocheiropteris and to subtropical forests of Eastern India and Ctenopteris to I he temperate regions. Drynaria, Microsorium, Polypodium and Pleopeltis exhibit comparatively greater ecological amplitudes, extending from tropical to temperate forests, the genus Pleopeltis ascending to the subalpine meadows. Colysis, Aglaomorpha, Belvisia, Pyrrosia and Leptochilus occur both in the tropical and subtropical forests ; Loxogramme, Crypsinus, Arthromeris and Goniophlebium are common both to the subtropical and temperate forests.

Polypodium niponicum var. wattii, P. lachnopus, and Microsorium membranaceum are comparatively more widespread than other ferns in Eastern India, and occur from tropical (0-900 m.) to temperate (1,800-2,700 m.) altitudes/forests. Pyrrosia floccigera, P. flocculosa, P. heteractis, P. lanceolata, P. lingua, P. manii, P. nuda, P. stenophylla, P. subfurfuracea, Microsorium lucidum, M.pteropus, Polypodium erythro- carpum, P. microrhizoma, Pleopeltis contorta, P. excavata, P. pseudo- nuda. Colysis hemionitidea, C, pedunculata, Aglaomorpha coronans and Drynaria quercifolia spread from the tropical to subtropical forests/ altitudes (0-1,800 m.). Drynaria propinqua, Crypsinus griffithianus, C. malacodon, Arthromeris himalayensis, A. wallichiana, Loxogramme involuta, L. lanceolata, Goniophlebium argutum, G. subauriculatum, Pleopeltis kashyapii, P. loriformis, P. macrosphaera var. asterolepis, P. subconfluens, P. thunbergiana and Microsorium superficiale range from the subtropical to temperate forests/altitudes (900-2,700 m.). Belvisia mucronata, Pyrrosia adnascens, P. beddomeana, P. nummulari- folia, Drymoglossum sp., Microsorium punctatum, M. rubidum, Lepto­ chilus axillaris, L. decurrens, Dipteris wallichii. Polypodium niponicum, Pleopeltis caudato-attenuata, P. macrosphaera, P. nuda, P. oosphaera. Colysis elliptica, and Drynaria sparsisora are restricted to the tropical forests. Colysis elliptica var. pothifolia, Loxogramme avenia, L. scolo- pendrina, Crypsinus crenatopinnatus, C. ebenipes, C. oxylobus, C. rhynco- phyllus, C. stracheyi, Arthromeris lehmanni, A. tenuicauda, A. wardii. Polypodium ammoenum, Goniophlebium molle, G. argutum var. khasiana, Pleopeltis bicolor, P. sordida^ P. ussuriensis, Neocheiropteris phyllomanes. Lemmaphyllum carnosum, Behisia henryi, Pyrrosia boothii. Micro- sorium dilatatum, M. fortunei, M. hymemdes, M. zippelii, and Lepto- chilus mimtulus are apparently confined to the subtropical forests. Polypodium atkinsoni, P subammoenum, Crypsinus stewartii, Loxo- gramme parallela, and Ctenopteris subfaicata presumably require less light and cooler atmosphere and are restricted to temperate forests of the Eastern Himalayas.

E c o l o g y

Most of the Polypodiaceae are small ferns and grow best as epi­ phytes under the canopy of tropical, subtropical and temperate forests. Such preference of habitat imposes severe limitations lo overcome which the different species resort to various types of adaptative mechanisms as discussed by Holttum (1954) and reviewed by Panigrahi (1958). The major part of the epiphytic community are sun-epiphytes and grow on moss-covered tree-trunks which retain rain-water and keep the substratum humid by absorbing atmospheiic moisture. They grow also on humus-covered rocks in the forest bed or on bare rock- boulders in the forest streams. Such habitats not only ensure abun­ dant supply of light but are also suitable for water economy of this community. Often, these sun-epiphytes are associated with orchids (and also with Aeschynanthes, Polygonatum and Smilacina) and some grasses among the angiosperms and Selaginella, species of Davalliaceae, Aspieniaceae and Vittariaceae among the Pteridophytes. The rhizomes of these genera penetrate the moss layer or humus- cover. Polypodium with its 8 species and Goniophlebium have wide- creeping rhizomes which are stout (P. ammoenum, P. lachnopus, G. sub- auriculatum) or slender (P. atkinsonii, P. microrhizoma) and glaucous bearing a few deciduous scales {P. niponicum) or covered with blackish- brown lanceolate scales {P. lachnopus, P. microrhizoma, G. argutum). in majority of the species the fronds are fleshy ; P. atkinsoni and Pleopeltis excavata var. scolopendria restricted to temperate altitudes, are characterised by membranous fronds. The other species of Pleopeltis, growing in similar situations, exhibit different ecological adaptations. One group, represented by P. contorta, has the margin of their fronds inrolied in dry weather and lamina curled downwards, thus reducing the transpiring surface. A second group, represented by P. kashyapii, possesses dense stiff roots and bears valvetty fronds covered by scales on the undersurface. P. ussuriensis, on the other hand, has thin dull green fronds bearing brown lanceolate scales. A third group is represented by P. excavata and P. excavata var. scolo­ pendria and possesses stout wide-creeping rhizomes (covered with dull brown scales) and membranous chartaceous fronds of very thin texture. At the onset of dry weather, the leaves are shed, thus reducing the loss of water by transpiration. P. subconfluens, P. thunbergiana and P. pseudonuda represent the fourth category of species. Their rhizomes are covered with scales and bear tufted dark green, fleshy and leathery fronds which do not wither or inroll in winter. Of these, P. pseudonuda shows the greatest degree of tolerance and winter hardiness ; its fronds remained green and fresh at Shillong, even when the ground tempe­ rature became — 2°. C. in the winter of 1962.

The genus Pyrrosia\ confined to tropical and subtropical forests, includes 2 types of species : (1) with the fronds fleshy, sparsely tomen- tose beneath (with stellate hairs) and sori deeply sunk in the tomentum (P. adnascens, P. numularifolia, P. angustata, P. floccigera, P. matinii, P. boothii) ; and (2) with the fronds thick, chartaceous or coriaceous, becoming glabrous at age {P. nuda) and, sori not sunk {P. lingua, P. longifolia).

Among Microsorium s.pp., M. hymenodes possesses climbing items thin, tough, dull green fronds; M. superficiale has wide creeping rhizomes with coriaceous, dark green fronds; M. zippellii is charac­ terised by slender creeping rhizome with thin fronds having decurrent lamina. M. pteropus is terrestrial or lithophytic on humus-covered rocks near swamps or near water-courses, sometimes on wet rock ; its rhizome is slender and the lamina thin. M. punctatum, on the other hand, possesses great ecological tolerance and with its stout, short-creeping rhizome bearing fleshy leathery fronds, occurs from tropical moist deciduous to evergreen forests. Leptochilus axillaris is another climbing fern of the evergreen forest, while L. decurrens is a terrestrial/lithophytic/epiphytic species growmg on moss-covered tree-trunks ; L. decurrens var. lanceolatus is a lithophyte rooting firmly on bare rock-boulders in the bed and bank of running streams. Colysis elliptica inhabits humus-covered rocks along the side of streams and possesses creeping rhizomes and tufted fronds, which become blackish on drying.

Drymmoglossum heterophyllum ( = D. piloselloides) is an epiphyte of the drier tropical habitats. Its wiry wide-creeping rhizome with dull brown narrow scales bears fleshy fronds with sparse stellate hairs beneath. The rhizome creeps along trunks of trees and are covered at times with soil nests of white ants. At times the branches of Arto- carpus integrifolia and of other trees and shrubs in the plains of Assam are covered with this epiphyte which becomes conspicuous from a dis­ tance in January-March,

Crypsinus crenatopinnatus grows on rocks or on grassy mounds of hills and possesses slender creeping rhizome. C. ebenipes is an epi­ phyte on mossy tree-trunks and possesses wide creeping rhizomes covered with shining black stiff ciliate scales. C. oxylobus and C. griffithianus have coriaceous fronds with cartilaginous margins ; C. stracheyi is characterised by dull green coriaceous fronds with distinctly spinescent margins. The genus Arthromeris, which is somewhat sympatric with Crypsinus, has fronds with a broad hyaline, cartilagi­ nous (A, wardii) margin. Loxogramme is characterised by fleshy fronds which remain green over long periods, like some species of Pleopeltis Modification of the basal portion of the pinnate leaf of Aglamorpha coronans and the development of short brownish nest leaves for humus collection in the genus D y n a r ia are too well known (c/. Nayar, 1954 ; Panigrahi, 1958) to n;;d emphasising here. That the development of the nest leaves is purely an ecological adaptation for humus collec­ tion, may presumably be established from the fact that D. propinqua and D. quercifoUa which normally develop scale leaves in nature, did not produce any nest'leaves over a period of 2 years when cultivated in earthernware pots containing humus-leaf-mould and sand mixture in the experimental Garden at Shillong

Dipteris wallichii grows on slopes of cliffs in the shade on the banks of streams in the Kameng Frontier Division. The rhizome creeps on sandy and calcareous rocks. The species was collected many limes in the wild and planted in earthernware pots as well as on rocky beds near a stream, in the shade, without success. The failure to cul­ tivate a terrestrial species in the Experimental Garden at Shillong where scores of epiphytes were successfully transplanted may indicate that D. wallichii survives in ext .mely specia ised habitats only.

S u m m a r y

The relative richness and distribution, both with regard to the occurrence and abundance of the species and genera of the family Polypodiaceae in the Eastern, Southern and North-Western sectors of India and in the tropical, sub-tropical, temperate and sub-alpine forest types and their ecological adaptations, are described.

A cknowledgements

Thanks are due to the Director, Botanical Survey of India, Calcutta, for constant encouragement and to the Council of Scientific and Industrial Research, New Delhi, for the award of a Junior Research Fellowship to the Junior author and other financial assistance during the course of investigation at Shillong between 1960-62,

R efer en ces

Beddome, R. H. 1883 and J892. Hand-book to the Ferns of Brilish India, Ceylon and Malay Peninsula. Thacker Spink and Co., Calcutta.

C o p e l a n d , E. B. 1947. Genera Filicum. Chronica Botanica, Waltham, Mass.

F is c h e r , C. E. C. 1938. The Flora of Lusha! Hills. Rev. bat. Surv. India 12 (2): 75-161.

H o l t t u m , R . E . 1954. A Revised Flora of Malaya, Vol. II. Ferns oj Malaya. Government Printing Office, Singapore. Hope, C. W. 1899-1904. The ferns of North-Western India. J. Bombay nat. H ist. Soc. 12; 527-38, 621-33; 13: 25-36, 236-51,443-61, 657-71 ; 14: 119-27, 252-66, 458-80, 720-49; 15: 67-111, 415-29,