Taxonomy and Conservation Status of Pteridophyte Flora of Sri Lanka R.H.G. Ranil and D.K.N.G. Pushpakumara
University of Peradeniya
Introduction The recorded history of exploration of pteridophytes in Sri Lanka dates back to 1672-1675
when Poul Hermann had collected a few fern specimens which were first described by Linneus
(1747) in Flora Zeylanica. The majority of Sri Lankan pteridophytes have been collected in the
century during the British period and some of them have been published as catalogues
and checklists. However, only Beddome (1863-1883) and Sledge (1950-1954) had conducted
systematic studies and contributed significantly to today’s knowledge on taxonomy and diversity
of Sri Lankan pteridophytes (Beddome, 1883; Sledge, 1982). Thereafter, Manton (1953) and
Manton and Sledge (1954) reported chromosome numbers and some taxonomic issues of
selected Sri Lankan Pteridophytes. Recently, Shaffer-Fehre (2006) has edited the volume 15
of the revised handbook to the flora of Ceylon on pteridophyta (Fern and Fern Allies).
The local involvement of pteridological studies began with Abeywickrama (1956; 1964;
1978), Abeywickrama and Dassanayake (1956); and Abeywickrama and De Fonseka, (1975)
with the preparations of checklists of pteridophytes and description of some fern families.
Dassanayake (1964), Jayasekara (1996), Jayasekara et al., (1996), Dhanasekera (undated),
Fenando (2002), Herat and Rathnayake (2004) and Ranil et al., (2004; 2005; 2006) have also
contributed to the present knowledge on Pteridophytes in Sri Lanka. However, only recently,
Ranil and co workers initiated a detailed study on biology, ecology and variation of tree ferns
(Cyatheaceae) in Kanneliya and Sinharaja MAB reserves combining field and laboratory
studies and also taxonomic studies on island-wide Sri Lankan fern flora. As a result, Ranil et al. (2010a; 2010b) have described two new pteridophyte species from Sri Lanka and identified
conservation priorities for Sri Lankan tree ferns in 2011 (Ranil et al., 2011). Ranil et al.,
(in prep.) reviewed and revised the list of endemic pteridophytes in Sri Lanka.
Currently, about 348 pteridophyte taxa from 30 families have been recorded from Sri Lanka,
of which 50 taxa are reported to be endemic to the country (Shaffer-Fehre, 2006). Among
Asian countries, Sri Lanka is second only to Taiwan in terms of the number of pteridophyte
species per 10,000 km
(Ranil et al., 2008a). Geographical isolation, and a wide range of
climatic, elevational and soil type variation in Sri Lanka may have resulted in rich diversity
of pteridophyte flora as well along with exceptionally high level of endemism. It is reported
that Sri Lankan pteridophytes have strong phyto-geographical relationships with South Indian
species. Further, both the Sri Lankan and the South Indian pteridophyte flora also have phyto-
geographical relationship with three regions, namely the Sino-Himalayan flora, the Malesian
flora from South East Asia, and an African element connected with the Seychelles, Mascarenes,
Madagascar and East Africa (Fraser-Jenkins, 1984). Despite historical and recent information
on pteridophyte flora of Sri Lanka, this is the first instance that the pteridophyte flora has been
assessed based on the national Red Listing criteria.
Taxonomy The present knowledge of ptridophytes is largely based on Shaffer-Fehre (2006) which is
mainly based on morphology and specimens of existing herbarium collections rather than new
information. It has been prepared during 1993-1995 period but published in 2006. However,
with the advancement of plant molecular studies, taxonomic status of many fern species have
changed and many revisions have been made. On the other hand, recently an extensive
field survey of South Indian fern flora has been carried out, though such information has not
been widely published yet. Recent review of endemic pteridophyte flora in Sri Lanka parallel
to information generated through South Indian survey via personal communication revealed
that the changes of number of endemic taxa from 50 (Shaffer-Fehre, 2006) to 44 (Ranil et al., in prep.). All these indicated the need of a systematic review of the taxonomy of Sri
Lankan pteridophytes based on detailed field works and existing herbarium collections and
also considering with advances of taxonomy and systematics due to molecular studies on
pteridophytes. For the red listing process, except for three families, namely Aspleniaceae,
Cyatheaceae and Thelypteridaceae (where there is no agreement among pteridologists to
place Sri Lankan species within families, hence followed Shaffer-Fehre (2006), all species
have been arranged based on the linear sequence of extant families and genera of lycophytes
and ferns proposed by Christenhusz et al., (2011). Changes of genera and families according
to Christenhusz et al. (2011) are given in Table 1.
Table 1: Changes of genera and families based on recent classification proposed by
Christenhusz et al. (2011).
Taxa Flora of Ceylon (2006) by Shaffer-Fehre (2006) Redlist (2012) based on Chris- tenhusz et al. (2011) Genera Antrophyum Vittariaceae
Distribution Limited research has been conducted to identify distribution of pterdophyte flora in Sri Lanka.
About 81% of pteridophyte specimens in the National Herbarium have been collected from
the wet zone area of the country (Jayasekera and Wijesundara, 1993). The wet zone which
accounts for only one third of the country’s total land area also contains almost all endemic
pteridophytes except one species (Ranil et al., in prep.). Further, study on distribution pattern
of endemic pteridophyte flora of Sri Lanka revealed that those are more-or-less equally
distributed among the wet zone areas of the up, mid and low countries with 34, 31 and 32 taxa,
respectively (Ranil et al., 2008a). Majority of endemic pteridophytes (78%) of Sri Lanka had
been collected from the Central Province where Nuwara Eliya district alone provided the highest
number of endemic taxa collected with 34 taxa followed by Sabaragamuwa and Southern
provinces. Even though some species occur in a few districts, their known occurrence has
been limited only to a few isolated localities (i.e. Cyathea hookeri, C. sinuata, C. sledgei and C. srilankensis; Ranil et al., 2010a; 2010b). Long duration of rainfall and high relative humidity
associated with elevational gradient may be one of the reasons for the presence of higher
number of endemic taxa in the wet zone and the Central Province. In addition, close proximity
to the Botanical Gardens of Peradeniya and Hakgala had also influenced a higher number of
species collections from the Central Province and Nuwara Eliya district.
Endemic and endangered tree ferns in lowland rainforests. A: Cyathea sledgei Ranil et al.,: A recently described new endemic tree fern species in Kanneliya
B: Cyathea srilankensis Ranil: A recently discovered new endemic tree fern species in Beraliya
proposed forest reserve.
C: Cyathea sinuata Hook. & Grew.: The only known simple leaf tree ferns in the world.
Two endemic ferns species in southern lowland rainforests. A: Tectaria thwaitesii (Bedd.) Ching:An endemic fern species in roadside banks of Kottawa forest
B: Oreogrammits sledgei (Parris) Parris: An endemic fern species grows on moist rock in Sinharaja
world heritage site.
A B C A B
Threats Vast majority of pteridophyte flora and almost all endemic pteridophytes in Sri Lanka are
confined to the wet zone areas of the lowland, sub montane and montane regions. However,
most of the remaining forests in the wet zone area are fragmented and small. They are
continued to be degraded due to illegal encroachment and suffer further fragmentation due to
higher population densities in such areas. The area is highly subjected to habitat loss, spread
of alien-invasive species, soil erosion and environmental pollution. These are considered
as the most immediate threats to the pteridophyte flora of Sri Lanka. In areas such as the
Knuckles region, the forest understorey which is the main habitat for pteridophytes has been
cleared for cardamom cultivation whereas in Udawattakele forest understorey is invaded by
alien-invasive species; also make significant threats to regeneration of pteridophytes. Another
threat of increasing importance is the illicit removal and over exploitation of ornamentally
important rare ferns from the wild. These problems will be worsening by change of climate
and increasing human population pressure.
Conservation issues The effective conservation of Sri Lankan pteridophyte flora will depend largely on how effective
the conservation of natural forests in the wet zone areas of the country. For this, minimizing of
fragmentation and habitat loss through effective land use planning and a sound policy framework
is a must. Further, according to the present Red Listing, of the 335 pteridophyte species,
219 species (66%) are listed as threatened species (20, 41, 87 and 71 species are critically
endangered and possibly extinct (CR(PE)) critically endangered (CR), endangered (EN) and
vulnerable (VU). Another 40 species are listed as near threatened (NT). This highlighted that, in
addition to conservation of natural forests in the wet zone areas, monitoring of populations of at
least threatened species is a necessary to understand effectiveness of the in situ conservation of
pteridophyte flora. At present, ex situ conservation is limited to a few local species at the Royal
Botanic Gardens, Peradeniya and Botanic Gardens of Hakgala and Henerathgoda. Therefore,
strengthening of ferneries of the network of the National Botanic Gardens is urgently required as
a supplementary conservation measure for Sri Lankan pteridophytes.
Research gaps and needs Further enhancement of current knowledge and understanding of pteridophytes flora needs
several measures. As highlighted a comprehensive taxonomic revision need to be carried out
in the light of recent floral survey in the South Asia and recent advances of taxonomy due to
use of molecular investigations. A close collaboration between pteridologists in India (as well
as elsewhere) and Sri Lanka is a pre-requisite. Much of the specimens of pteridophytes have
been collected from 1847 to 1900 by European pteridologists and deposited in herbaria of
elsewhere than the National Herbarium. Thus, an island-wide floristic survey on pteridophyte
taxa is urgently required in Sri Lanka which helps to revise the taxonomy, distribution and
other conservation issues of the island pteridophyte flora. Upgrading of the collection of the
National Herbarium is also a must and should be carried out parallel to the floristic survey.
Further, recent work by Ranil et al., (2008b) provides encouraging results on domestication
of C. walkerae and need to expand to other species which has commercial potentials. Public
awareness programs on the conservation and sustainable use of pteridophytes should also be
initiated promoting in situ and ex situ conservation.
Conclusions and Recommendations Lowland rainforests, sub-montane and montane forests are the major natural vegetation
types supporting the biodiversity of Pteridophytes in Sri Lanka. However, these ecosystems
are heavily affected by various biotic and abiotic influences and already highly fragmented.
Increasing population pressure and climate change further worsen the situation. These facts
highlight the importance of conserving the remaining forest ecosystems of the wet zone of
the country. It is also essential to conduct further research to fill the gaps of knowledge of
Sri Lankan pteridophytes which will provide a basis to resolve many of the taxonomic and
conservation issues pteridophytes face today.
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Family EX EW CR (PE) CR EN VU NT DD LC Total Threatened Total Species Aspleniaceae
Totals 21 (5) 42 (10) 88 (11) 70 (12) 40 (9) 12 (1) 63 (1) 200 (33) 336 (49) Table 13: Summary of the Status of Pteridophytes in Sri Lanka (Endemics are shown in bracket)
Table 14: List of Pteridophytes in Sri Lanka (Endemic species are marked in
Bold letters )
Family/ Scientific Name Common name NCS Criteria GCS Family : Lycopodiaceae Huperzia ceylanica (Spring) Trevis.
Huperzia hamiltonii (Spreng.) Trevis.
Huperzia phlegmaria (L.) Rothm.
Huperzia phyllantha (Hook. & Arn.) Holub