Journal of Threatened Taxa |
www.threatenedtaxa.org | 26 October 2021 | 13(12): 19781–19790
ISSN 0974-7907 (Online) | ISSN 0974-7893
(Print)
https://doi.org/10.11609/jott.7488.13.12.19781-19790
#7488 | Received 02 June 2021 | Final
received 30 July 2021 | Finally accepted 20 August 2021
On the pteridophytes of Bherjan-Borajan-Padumoni Wildlife Sanctuary, Assam, India
Pranjal Borah 1 & Jayanta Barukial
2
1 Department of Life Sciences,
Dibrugarh University, Dibrugarh, Assam 786004, India.
2 P.G. Department of Life Sciences,
Debraj Roy College, Golaghat,
Assam 785621, India.
1 borahpranjal27@gmail.com
(corresponding author), 2 barukialjayanta@gmail.com
Editor: Anonymity
requested. Date of publication:
26 October 2021 (online & print)
Citation: Borah, P. & J. Barukial (2021). On the
pteridophytes of Bherjan-Borajan-Padumoni Wildlife
Sanctuary, Assam, India. Journal of
Threatened Taxa 13(12): 19781–19790. https://doi.org/10.11609/jott.7488.13.12.19781-19790
Copyright: © Borah & Barukial 2021. Creative
Commons Attribution 4.0 International License. JoTT
allows unrestricted use, reproduction, and distribution of this article in any
medium by providing adequate credit to the author(s) and the source of
publication.
Funding: Self-funded.
Competing interests: The authors
declare no competing interests.
Author details: Pranjal Borah is a PhD scholar at Dibrugarh University, Assam,
pursuing research in the area of plant taxonomy. Dr. Jayanta Barukial is the
Associate Professor and Head of the Department of Botany and PG Department of
Life Sciences, Debraj Roy College, Assam and a
recognized PhD supervisor of Dibrugarh University. His research interest is in
the field of plant taxonomy, cytology, molecular taxonomy, environmental
issues.
Author contributions: All authors equally contributed
to the present study.
Acknowledgements: The authors are grateful to the
principal chief conservator of forest (wildlife), Assam and the Assam State
Biodiversity Board for giving the necessary permissions for field surveys. Also
thankful to local forest officials for providing necessary help and guidance
during the field trips. The authors are also grateful to Dr.
Pankaj Chetia, asst. professor, Dept. of Life
Sciences, Dibrugarh University, Assam and Mr. Nakul Neog,
asst. professor, Sadiya College, Assam for their
advice and help.
Abstract: A preliminary survey on the
pteridophytic flora of Bherjan-Borajan-Padumoni
Wildlife Sanctuary of Assam, India revealed a total of 33 species belonging to
23 genera and 15 families. Most of the species belong to the family Pteridaceae followed by Polypodiaceae
and Thelypteridaceae. A brief taxonomic description
of each species is provided. Stenochlaena palustris (Burm.f.) Bedd., an edible fern, grows abundantly all over,
especially in the openings and clearings.
Keywords: Fern, Polypodiaceae,
Pteridophytic flora, Pteridaceae, Stenochlaena,
taxonomic description, Thelypteridaceae.
INTRODUCTION
Pteridophytes, also known as ferns and fern-allies,
flowerless and seedless plants that once dominated the world vegetation 280–230
million years ago. The main plant body is sporophytic
and the dominant phase in its life cycle. Chapman (2009) estimates that there
are about 12,000 species of ferns and fern-allies across the world. According
to Moran (2015), “worldwide, there are about 13,600 species of ferns and
lycophytes”. According to a survey, the pteridophytic flora of India comprises
around 1,000 species belonging to 191 genera and 67 families including 47
endemic Indian ferns (Dixit 1984) and in another report, more than 1,100
species of pteridophytes belonging to 144 genera and 34 families with about 235
endemic species (Chandra 2000) from India. According to Fraser-Jenkins et al.
(2017), “altogether there are about 1135 species including 42 exotics and 53
further subspecies”, from the Indian subcontinent.
The Bherjan-Borajan-Padumoni
is one of the smallest wildlife sanctuaries of Assam covering 7.22 km2
of area spreading across three blocks located in Tinsukia district of the Upper
Brahmaputra Valley of Assam, India which consists of three separate forests,
namely Bherjan, Borajan,
and Padumoni. The forest is the home for an
endangered primate species, i.e., Western Hoolock Gibbon. Bherjan,
Borajan, and Padumoni are
tiny isolated pockets of lowland tropical forest covering an area of 105 ha,
493 ha, and 176 ha respectively and an ideal
habitat for primate species like the Bengal Slow Loris, Assamese Macaque,
Pig-tailed Macaque, Rhesus Macaque, Capped Langur, Stump-tailed Macaque, and
Western Hoolock Gibbon. The three areas are disjoint and unconnected by
tea gardens and human settlement. These are entirely on the flat plains of the
Brahmaputra Valley. There are small, scattered marshes, with swamps, covered
with dense growth of grass and Alpinia herb.
The natural vegetation of all these areas is tropical wet evergreen
‘rainforest’ type. Bherjan is almost entirely covered
with trees with a closed canopy. The original vegetation has been replaced by a
fairly old mixed plantation dominated by the deciduous species Lagerstroemia
parviflora and Terminalia myriocarpa. The Padumoni part
is mostly in a degraded state due to large-scale felling. The canopy has been
very badly broken up. Only a few mature trees of Artocarpus, Bombax, Lagerstroemia, and Mesua species can be seen. Borajan
is a pocket of excellent rainforest, dominated by Dipterocarpus
macrocarpus. Except for Teak, all the
species as in the other two forest pockets are found. Bamboo species are found
in all areas.
In Assam, a few systematic works on pteridophytes have
been accomplished, like Kachroo (1953), Panigrahi (1960, 1968), Panigrahi
& Chowdhury (1961, 1962), Dutta et al. (1980), Handigue
& Konger (1986), Kachroo
et al. (1989), Borthakur et al. (2001, 2018), Devi
& Majumdar (2003), Sen & Ghosh (2011), and Kalita
(2015).
METHODS
A number of field visits were undertaken to the study
area in the year 2019–2020 (Figure 1). The different pteridophytes were
collected from a range of habitat; however, those species which are Red Listed
(IUCN) or used as food or shelter were left untouched. Under such
circumstances, digital photographs of the concerned species were taken. The
specimens were preserved and studied with standard literature like Baishya & Rao (1982), Jamir & Rao (1988), and Borthakur et al. (2001, 2018). The plants were collected from the field,
cleaned, and pressed for the preparation of herbarium. Herbariums are prepared
by following standard herbarium technique (Jain & Rao 1977) and deposited
at the Botany Department, Debraj Roy College, Golaghat, Assam. Digital photographs of the specimens were
also taken and some of them are displayed (Image 1).
The families are enumerated in text according to
Fraser-Jenkins (2009). However, the genera and species within the families are
listed alphabetically. The taxonomic citation is based on published literature
and IPNI, Tropicos, and The Plant List.
RESULTS
A total of 33 species of pteridophytes belonging to 23
genera and 15 families are recorded. The plants are enumerated with a brief
taxonomic description of each species.
Selaginellaceae
1. Selaginella
monospora Spring; Collection No. DRC-
5005.
Terrestrial. Stem about 40 cm long, prostrate,
ascending, branched. Leaves dimorphic, green, midrib prominent, lateral leaves
ovate. Strobilus up to 8 mm long, terminal, simple, sporophylls
spiral, spore green.
2. Selaginella
semicordata (Wall. ex Hook. & Grev.) Spring; Collection No. DRC-5006.
Terrestrial. Stem slender, branched with related
dichotomy, rhizophore arises from forking. Leaves
spirally arranged, lanceolate, entire, membranous. Strobilus up to 0.6 cm long,
sporophyll lanceolate, ciliate at base; sporangia
oval, orange in colour, spore oval, dark brown.
Marattiaceae
3. Angiopteris
evecta (G.Forst.)
Hoffm.; Collection No. DRC- 5015.
Terrestrial. Tree like fern. Rhizome erect,
cylindrical, broad. Stipes swollen at base, adaxially flattened, abaxially
rounded, whitish linear streaks all over, with small brown scales and minute
hairs. Lamina bipinnate; pinnae subopposite, with long swollen stalk,
oblong-lanceolate, veins simple or forked twice, almost parallel, reaching the
margin. Sori sub-marginal, ellipsoid; sporangia up to
six pairs in two rows, which is boat-shaped. Spores hyaline, tetrahedral, pale
green.
Gleicheniaceae
4. Dicranopteris
linearis (Burm.f.)
Underw.; Collection No. DRC- 5016.
Terrestrial. Rhizome long creeping, densely covered by
hairs, scales absent; hairs minute, multicellular, reddish-brown. Stipes
slender, straggling, rigid and polished; apical bud covered by brown hairs.
Fronds pinnate or dichotomously branched; margin curved, deeply covered with
brown hairs; rachises repeatedly forked, covered with dark-brown hairs; veins
prominent, 2-forked, free; lamina light green; texture hard. Sori small, globose, without paraphyses, in the two rows on
both sides of the costa. Spores numerous, trilete, deeply grooved.
Polypodiaceae
5. Microsorum pteropus (Bl.) Copel.;
Collection No. DRC- 5021.
Aquatic. Rhizome creeping, fleshy, green, apex scaly; lanceolate. Fronds
simple or 3/5 - lobate, lanceolate, veins distinct above and below, main veins
rather wide apart, lamina very dark, dirty green, often black when dry. Sori small, globose, scattered irregularly within the main
areoles; sporangia slender stalked, oval. Spores yellowish-green.
6. Microsorum
punctatum (L.) Copel.;
Collection No. DRC- 5025.
Epiphyte. Rhizome short creeping. Fronds without
distinct stipe, simple, sessile, lanceolate or elliptic, base decurrent, margin
entire, midrib across at the base, veins visible but not prominent; pinnae
glabrous above and below, dark green when fresh, blackish when dry. Sori numerous, small, round, irregularly scattered on upper
half of the frond; sporangia oval, short-stalked. Spores yellowish-green.
7. Pyrrosia
lanceolata (L.) Farewell.; Collection
No. DRC- 5029.
Epiphyte. Rhizome wide creeping, slender, clothed with
scales; base rounded, margin profusely hairy, entire. Lamina simple, lanceolate
acute apex, base decurrent, entire or wavy, green and glossy above, brownish
below, upper surface glabrous, lower surface densely covered by stellate hairs,
veins immersed; lamina wrinkle up on drying. Sori
irregularly distributed on the anterior half of lamina; sporangia dark-brown,
naked. Spores greenish-yellow.
8. Pyrrosia
piloselloides (L.) M.G.Price;
Collection No.:- DRC-5032.
Epiphyte. Rhizome long creeping, clothed with scales;
lamina dimorphic, simple; sterile lamina sessile or shortly stalked, roundish
or obovate, base cuneate, margin entire; stipe of fertile frond scaly at base,
grooved adaxially, straw-coloured; fertile lamina
linear to oblong, apex round, base decurrent, margin entire; veins indistinct. Sori marginal, linear, continuous along the tip of lamina;
sporangia oval, short stalked dark-brown. Spores oval to elliptic, light-brown.
Lygodiaceae
9. Lygodium
flexuosum (L.) Sw.; Collection No.
DRC- 5037.
Climber. Rhizome creeping, short, covered by
dark-brown, multicellular, uniseriate hairs. Stipes
glabrous, abaxially rounded, adaxiaily flattened,
dark-brown. Fronds widespreading, tripinnate,
glabrous; primary pinnae alternate, bears two to three pinnules alternately;
pinnules oblong-lanceolate, simple or terminal leaflets forked, basal leaflets
often large, separate or lobed with 2–3 leaflets, sterile leaflets finely
toothed; texture firm; rachis and costa densely or sparsely pubescent all over;
veins distinct, free, reaching the margin; fertile leaflets a little narrower
than the sterile ones. Sporangia arranged adaxially protruding from the margin;
sporangia large, short stalked, about five pairs, arranged in two rows,
alternate.
10. Lygodium
japonicum (Thunb.) Sw.; Collection No.
DRC- 5038.
Climber. Rhizome long creeping, covered with black
hairs. Stipes scaly at base. Fronds wide-spreading, tripinnate; primary pinnae
forked, opposite; fertile pinnae much contracted giving an appearance of
dissected lamina; texture herbaceous; primary rachis scabrous; secondary rachis
ridged; veins distinct, free, reaching the margin. Sori
finger like, marginal projections which are greenish when young and dark brown
at maturity; sporangia short stalked, arranged in two rows, alternate. Spores
small, numerous.
Pteridaceae
11. Acrostichum
heterophyllum L.; Collection No. DRC-
5040.
Epiphytes. Rhizome long creeping, densely covered by
scales; apex acuminate, centre dark brown, pale-brown
in the rest. Stipes of sterile fronds covered with scales similar to rhizome.
Lamina dimorphous, simple or elliptic, apex rounded, margin entire; costa and
veins indistinct, immersed; texture thick, fleshy, more or less covered by
stellate hairs when young, sparsely or rarely when matured, lamina pale or
dark-green; linear oblong, apex rounded. Sori
confluent along the tip of lamina, sporangia oval, short stalked, intermingled
with stellate hairs, dark-brown. Spores oval to elliptic, hyaline, light-brown.
12. Adiantum capillus-veneris
L.; Collection No. DRC- 5055.
Terrestrial. Rhizome short creeping, densely clothed
with brown, narrow, lanceolate, acuminate, entire scales; Stipes slender scaly
at base, glabrous and dark glossy above. Lamina bipinnate, lanceolate, cuneate
at base, lower margin straight or
concave and entire, outer margin rounded, lobed, lobes crenate, sterile lobes
with more or less rounded, finely toothed edges; rachis uncovered; veins
dichotomously branched. Sori elliptic or linear;
sporangia globose, small and short stalked. Spores smooth walled.
13. Pityrogramma calomelanos
(L.) Link.; Collection No. DRC- 5057.
Terrestrial. Rhizome short, erect, glossy above,
black. Lamina oblong-triangular, subcoriaceous,
bipinnate, pinnae in the lower half of the lamina more or less equal; gradually
shortened towards apex, lower surface covered with white waxy powdery
substance, lobes oblique, elliptic, toothed; rachis black-ebeneous,
glossy; veins dichotomously radiated, free. Sori
continuous throughout the lower surface. Spores tetrahedral.
14. Pteris
biaurita L.; Collection No. DRC- 5045.
Terrestrial. Rhizome erect, short, scaly at the apex;
linear-lanceolate, margin hairy, dark brown. Stipes glabrous except at base,
adaxially grooved. Lamina bipinnatifid, glabrous;
pinnae up to 12 pairs, sub-opposite, lanceolate, sessile or shortly stalked,
margin lobed, apex rounded, margin entire; pinnae pale green; veins distinct,
other veins forked once. Sori confluent along the
margin of the sinus but not reaching the apex of the lobes. Spores tetrahedral,
dark brown.
15. Pteris
ensiformis Burm.f.;
Collection No. DRC- 5046.
Terrestrial. Rhizome erect, short, scaly; scales linear-lanceolate,
entire, shining, dark-brown. Stipes glabrous, polished, slender, abaxially
rounded, adaxially grooved. Fronds dimorphous, but sometimes some fronds partly
fertile and partly sterile; Fertile lamina bi-pinnate, glabrous; the segments
very narrow and elongated, entire; lamina pale-green; rachis glabrous, grooved
above, pale-brown; veins distinct on both surfaces, simple or forked, free. Sori confluent, marginal, developing basipetally. Spores
dark brown, tetrahedral.
16. Pteris
longipinnula Wall. ex J. Agardh.; Collection No. DRC- 5047.
Terrestrial. Rhizome erect, densely clothed with
scales; scales linear, reddish-brown. Stipes erect, slender, abaxially rounded,
adaxially grooved, scaly at base. Lamina bipinnatifid,
with 3 - 8 pairs of lateral pinnae and an apical pinnae, apex caudate; lobes
gradually reduced towards apex, often auricled; rachis and surface of the
pinnae uncovered; spinules present on upper surface;
veins free, forked once. Sori marginal, continuous
nearly to the apex of the lobes. Spores triangular to ‘T’-shaped, dark brown.
17. Pteris
semipinnata L.; Collection No. DRC-
5048.
Terrestrial. Rhizome short-creeping, densely scaly;
dark brown. Stipes erect, tufted, slender, glabrous, dark brown at base, pale
brown above. Lamina pinnate, ovate-lanceolate, glabrous; upper part of lamina
cut down nearly to the rachis into numerous close entire linear lobes; costae
and costules minutely grooved on the upper surface;
veins free, fine, forked once. Sori linear,
continuous along the margins of lobes except quite near reaching the sinus.
Spores triangular to oval, pale brown.
18. Pteris vittata L.; Collection No. DRC- 5049.
Terrestrial. Rhizome suberect, short, densely covered
by scales at apex, membranaceous, entire, pale-brown.
Stipes pale-brown, clothed with linear, silky, pale-brown scales. Lamina simple
pinnate with a single, elongate, linear, terminal pinnae like the lateral ones;
pinnae numerous, opposite or subopposite, reduced to deflexed auricles, all
pinnae sessile, linear-lanceolate, acuminate at apex; veins simple or forked
once, free, distinct on both surfaces. Sori all along
the margin, except at base and apex; indusia membranaceous.
Spores round, yellowish-green.
19. Vittaria
elongata Sw.; Collection No. DRC- 5053.
Epiphyte. Rhizome short creeping, thick, slender
branched, densely scaly. Stipes flattened. Lamina simple, linear-oblong
lanceolate, gradually tapering towards both ends, apex acuminate, margin
entire, midrib distinct; veins slightly distinct above and below, simple,
immersed, parallel; lamina dark green. Sori linear,
confluent; sporangia short stalk. Spore pale yellowish-green.
Cyatheaceae
20. Cyathea gigantea
(Wall. ex Hook.) Holtt.
Terrestrial. Tree like fern. Trunk massive, erect,
densely covered by scales dark brown. Stipes tufted, glossy, scaly at base,
glabrous above, abaxially rounded, adaxially grooved, dark purple. Lamina
bipinnate, deltoid, dark- green when fresh, brownish when dry;
oblong-lanceolate, alternate, shortly stalked, about 20 cm apart, acuminate at
apex about 2 cm apart, apex acuminate, margin lobed half way to the costae,
rounded apex, margin crenate; texture of lamina herbaceous; rachis slightly
dark brown. Sori median on the veins, spherical and
inverted ‘V’ shape, exindusiate; sporangia numerous,
compact.
21. Cyathea
spinulosa Wall. ex Hook.
Terrestrial. Tree like fern. Trunk erect, up to 3 m or
more tall. Stipes and rachis strongly aculeate or spiny, scales
linear-lanceolate, long hair-pointed, black. Lamina bipinnate, short stalked;
rachis of pinnules and main veins of lobes scaly below, but the latter glabrous
above; lamina coriaceous; veins usually forked once, free. Sori
large, round, indusium completely covering the sorus
when young, soon breaking irregularly.
Dennstaedtiaceae
22. Microlepia
speluncae (L.) Moore; Collection No.
DRC- 5063.
Terrestrial. Rhizome long creeping, stout, hairy;
pale-brown. Stipes rounded below, grooved above, short hairy, purplish-green.
Lamina tripinnate or quadripinnate; pinnae about
eight pairs, alternate, petiolate; ovate-lanceolate, apex acuminate, largest pinnule
narrowly deltoid, subopposite or alternate, shortly stalked, basal acroscopic leaflet much larger than the rest; ultimate
pinnules, veins slightly distinct, forked once, free, not reaching the margin. Sori submarginal, near the base
of the sinuses between the lobes, indusia cup-shaped, hairy; sporangia copious.
Spores yellowish-brown.
Lindsaeaceae
23. Sphenomeris
chinensis (L.) Maxon; Collection No.
DRC- 5067.
Terrestrial. Rhizome short creeping, stout, covered by
scales; scales hair-like, stiff, dark-brown. Lamina tripinnate or quadripinnatifid, distal part bipinnatifid,
lanceolate, apex acuminate, acroscopic base truncate,
basiscopic base cuneate; secondary pinnae about eight
pairs, alternate, shortly stalked, acute; tertiary pinnae about three pairs,
alternate, shortly stalked, obovate, apex rounded, base cuneate. Sori marginal or submarginal at
the end of veins; indusial attached basally. Spores bilateral and brown.
Thelypteridaceae
24. Amblovenatum
opulentum (Kaulf.)
J.P.Roux.; Collection No. DRC- 5069.
Terrestrial. Rhizome creeping, densely scaly; scales
narrow, linear brown. Stipes erect, slender, grooved, hairy at grooves, scaly
at base. Lamina simple pinnate, lanceolate, apex acuminate; pinnae about 20–30
pairs, alternate or subopposite, sessile; apex obtuse or rounded, margin wavy,
clothed with small yellowish glandular hairs; lamina dark green. Sori mostly confined to lobes, globose, often much immersed
and visible as punch form dots on the upper surface; indusia thin, sporangia
slender stalked. Spores dark in colour.
25. Christella
parasitica (L.) H.Lev.;
Collection No. DRC- 5072.
Terrestrial. Rhizome creeping, densely scaly;
linear-lanceolate, apex acuminate, margin more or less clothed with short, soft
hairs. Simple pinnate, pinnae numerous,
alternate or subopposite, sessile, margin lobed two-third to the costa, lobes
up to 20 pairs, oblique, basal acroscopic lobe
slightly larger than the others; rachis copiously covered by long and short
hairs; costa, eostules and veins covered by short
acicular or glandular hairs; veins up to 10 pairs, upper surface covered with
thick, acicular hairs. Sori medial or submarginal on the veins up to five pairs.
26. Cyclosorus
interruptus (Willd.) H. Ito.; Collection no.
5065.
Terestrial. Rhizome long creeping, clothed with scales at the
apex; scales ovate, acuminate at apex, margin entire. Stipes slender, sparsely
scaly and black at the base, glabrous and brown above, adaxially grooved,
abaxially flattened. Lamina elliptic-lanceolate, simple pinnate with an apical
pinnae; lateral pinnae numerous, sessile or very shortly stalked, basal pinnae
not reduced, rachis grooved and hairy; veins slightly distinct below and
densely covered by long, soft acicular hairs, upper surface glabrous; lamina
pale green; sori medial on the veins, in two rows,
arranged in V-shaped; indusia reniform, hairy. Spores pale brown.
Aspleniaceae
27. Asplenium nidus L.;
Collection No. DRC- 5076
Epiphyte. Rhizome erect, short, stout, apex clothed
with scales. Stipes dark to pale brown, glabrous above, scaly at base; lamina
simple, lanceolate, gradually narrowed at both ends, glabrous; midrib strongly
raised on the upper surface, veins nearly simple or 2-forked; almost parallel. Sori linear, borne along each veinlet on upper half of the
lamina, nearly reaching margin from the midrib; indusia linear, narrow,
superficially attached at base, slightly curved, greenish-grey. Spores light
brown.
Athyriaceae
28. Diplazium
dilatatum Bl.
Terrestrial. Rhizome erect, stout, apex densely
clothed with scales; apex acuminate, margin with many teeth, thin, dark brown.
Stipes scaly at base, glabrous above, abaxially rounded, adaxially grooved.
Lamina ovate, bipinnate or tripinnatifid; primary
pinnae seven pairs, alternate, shortly stalked or sessile, slightly ascending,
pinnae up to 12 pairs, subopposite to alternate shortly stalked, simple or
forked once, reaching the margin, texture herbaceous; lamina dark green above,
pale green below, glabrous. Sori linear, confluent,
indusia linear, entire, pale brown; sporangia slender stalked. Spores oval,
pale brown.
29. Diplazium
esculentum (Retz.) Sw.
Terrestrial. Rhizome erect, apex densely covered by
scales, linear, lanceolate, apex long acuminate, dark-brown. Stipes stout,
erect, sparsely scaly at base, dark-brown at base, pale-brown above. Lamina
bipinnate at base, simple pinnate at apex, rarely simply pinnate, deltoid, apex
acuminate, base truncate, basal pair of pinnae slightly reduced; pinnae up to
seven pairs, basal one or two opposite or sub-opposite, others alternate;
petiolate, narrowly deltoid, with a deeply lobed terminal pinnae, apex acuminate,
lamina pale-green, hairs densely distributed all over the lamina. Sori in two rows near the margin, dark brown. Spores
reniform, pale-brown.
Dryopteridaceae
30. Bolbitis heteroclita (Presl.)
Ching; Collection No. DRC- 5082.
Terrestrial. Rhizome long creeping, soft, brittle,
apex clothed with ovate-lanceolate, darkbrown scales;
Stipes green, sparsely covered by scales. Fronds usually in two or three
alternate rows; they vary from simple to pinnate and loosely placed; pinnae
usually trifoliate, simple leaves and terminal pinnae of pinnate leaves
similar, veins prominent, lateral veins raised, secondary veins anatomising without included veinlets, marginal veins free.
Fertile lamina simple or pinnate; apical pinnae lateral, fertile lanceolate
with acute apex, margin smooth and shortly stalked. Sori
covering the whole lower surface and brown.
Davalliaceae
31. Araiostegia
divaricata (Bl.) M.Kato.;
Collection No. DRC- 5085.
Epiphyte. Rhizome creeping, densely scaly all over;
scales, apex long acuminate, base broad, thin, transparent, brown. Stipes firm,
erect, scaly at base, glabrous above, chestnut brown, tripinnatifid,
deltoid-lanceolate, apex acute or acuminate; apex acuminate, base cuneate;
secondary pinnae up to 12 pairs, alternate, sessile or shortly stalked, margin
deeply cut down to lobe nearly to the costules;
margin sharply toothed or crenate; veins not conspicuous, uniform, free, not
reaching the margin; lamina dark reddish-brown when dry, glabrous. Sori half cup-shaped, obliquely placed as regards the
central veins in the tooth, submarginal, brownish;
indusia tubular or half cup-shaped, as long as broad.
Blechnaceae
32. Blechnum
orientale L.; Collection No. DRC-
5087.
Terrestrial. Rhizome creel, densely scaly, massive,
linear-lanceolate, apex acuminate, shining, dark brown. Stipes tufted, erect, scaly at base, glabrous
above, reddish-brown at the base, grey brown above. Lamina ovate to
linear-lanceolate, apex acute, simple pinnate; costa grooved above, rounded
below; veins slightly distinct, simple or forked once or two times, free;
lamina pale green, glabrous above and below, glossy. Sori
linear along either side of the costa, continuous nearly to the apex, dark
brown; indusia narrow, firm with entire margin. Spores round to oval,
translucent, yellowish-brown.
33. Stenochlaena
palustris (Burm.f.)
Bedd.; Collection No. DRC- 5090.
Climber. Rhizome scandant,
long creeping, thick, sparsely scaly, often climbing on trees; scales ovate,
apex acuminate, margin ciliated, dark-brown at the centre,
pale-brown at the periphery. Lamina dimorphic; stramineous,
glabrous, adaxially grooved, abaxially rounded; simple pinnate; pinnae 8–15
pairs, lanceolate, apex acuminate, hard, rachis similar to stipe; veins
distinct, simple or rarely once forked, reaching the margin; lamina green,
glabrous on both surfaces, shining. Fertile lamina borne at the distal part of
the plant, more or less same size and shape with the sterile one, but pinnae
much contracted. Sori densely covering the lower
surface except midrib and the extreme apex; sporangia large, stalked, crowded.
Spores monoiete, pale-green, spinulose.
DISCUSSION
The vegetation of the study area is mostly dominated
by the angiosperms. Out of the 33 species of pteridophytes, two species belong
to fern-allies and 31 species belong to true ferns. The two species of
fern-allies belong to the family Selaginellaceae.
Considering the habitat, 25 plants are terrestrial, seven plants epiphytic, and
one aquatic (Figure 2). Among them, three species are trees, three species are
climbers and remaining 27 species are either herbs or shrubs (Figure 3). Three
species namely Angiopteris evecta (G.Forst.) Hoffm., Cyathea
spinulosa Wall. ex Hook. and Cyathea gigantea (Wall. ex Hook.) Holtt.
are tree ferns. Microsorum pteropus (Bl.) Copel. is the
only aquatic fern found there. Lygodium flexuosum (L.) Sw., Lygodium
japonicum (Thunb.) Sw., and Stenochlaena
palustris (Burm. f.) Bedd. are climbers. Cyclosorus
interruptus (Willd.) H. Ito is grown abundantly
in swamp areas. Pityrogramma calomelanos (L.) Link. is commonly called as silver
fern due to its silver colour spores and found to be
growing in the forest and also grow on stored bricks or nearby brick making
industries. Epiphytic ferns Microsorum punctatum (L.) Copel. and Asplenium
nidus L. are seen to be growing plentifully in tree trunks not only in the
forest but also adjoining areas. Diplazium esculentum (Retz.) Sw. is widely used as vegetables in
the nearby area. The fern species like Cyathea
gigantea (Wall ex Hook.) Holtt.
and Diplazium esculantum
(Retz.) Sw. were observed to be taken as food by Trachypithecus
geei during their study in Kakoijana
reserve forest, Assam. However, no record traced the existence of this
endangered primate species in the present study area. Due to the subsistence of
other primate species including the endangered Hoolock Gibbons, these two fern
species were kept unscathed and only digital photograph were taken.
The family Pteridaceae has
the greatest number of genera, i.e. 5; among them, the genus Pteris has highest number of species. In India, the
family Thelypteridaceae is represented by 80 species
and 16 hybrids (Fraser-Jenkins et al. 2017) while only three species are
recorded from the present study area. Most of the families and genera have a
single number of species (Table 1).
Table 1. Number of pteridophyte taxa in genera and
families.
|
Family |
Genus |
Number of taxa |
|
Selaginellaceae |
Selaginella |
2 |
|
Marrattiaceae |
Angiopteris |
1 |
|
Gleicheniaceae |
Dicranopteris |
1 |
|
Polypodiaceae |
Microsorum |
2 |
|
Pyrrosia |
2 |
|
|
Lygodiaceae |
Lygodium |
2 |
|
Pteridaceae |
Acrostichum |
1 |
|
Pteris |
5 |
|
|
Adiantum |
1 |
|
|
Pityrogramma |
1 |
|
|
Vittaria |
1 |
|
|
Cyatheaceae |
Cyathea |
2 |
|
Dennstaedtiaceae |
Microlepia |
1 |
|
Lindsaeaceae |
Sphenomeris |
1 |
|
Thelypteridaceae |
Amblovenatum |
1 |
|
Christella |
1 |
|
|
Cyclosorus |
1 |
|
|
Aspleniaceae |
Asplenium |
1 |
|
Athyriaceae |
Diplazium |
2 |
|
Dryopteridaceae |
Bolbitis |
1 |
|
Davalliaceae |
Araiostegia |
1 |
|
Blechnaceae |
Blechnum |
1 |
|
Stenochlaena |
1 |
For
figures & images - - click here
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