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assemblage of seedless vascular plants which have successfully invaded the land. They are

the primitive tracheophytes which lack flowers and seeds and they mainly reproduce by
means of haploid spores and exhibit independent alternation of generation. They represent the

evolution of vascular system and the emergence of seed habitat in plants, hence they are
considered to be a vital link between lower cryptogam group of plants and higher

spermatophyte group of plants in the heirarchial plant classification system .The study of
Pteridopytes in Kerala began with Van Rheede who included 19 illustrations and descriptions

of Pteridopytes in his monumental work Hortus Malabaricus. Prof. Madhusoodanan and

Sevichan (1991) studied various aspects of Pteridopytes of South India. They focused on rare
and endangered ferns and fern allies of Western Ghats of Kerala and discussed its

conservation. Manickam and Idayaraj (1992) published Pteridophytic flora of the Western

Ghats- South India.Pteridopytes plays many important and different roles in the ecosystem.
Azolla (Family – Azollaceae) is one among them. Azolla form symbiotic association with

nitrogen fixing, blue green algae - Anabaena azollae. Due to the nitrogen fixing property,
Azolla is used as biofertilizer for rice has been recognized in many countries including India,

Philippines, USA, Sri Lanka and Thailand (Ahluwalia et al, 2002). The remarkable activity
of Azolla to take up heavy metals from polluted water can be used for treatment of

wastewater (Sanyahumbi et al, 1998; Vermaat & Hanif, 1998).The ferns have a vital role in

bioremediation of waste water (Ma et al.2001). The non living biomass of Salvinia exhibit
equivalently high potential to remove heavy metal (Dhir et al., 2009). Thiruvananthapuram

district is known for its rich biodiversity with large number of endemics having special
relevance for its Conservation. Different habitat contain rich diversity of Pteridopytes

including many endemic and endangered species. The region offers innumerable
microhabitats for the surplus growth of pteridopytes yet pteridopytes in Thiruvananthapuram

district have not received much attention by plant explorers. Therefore the present study has

been carried to asses the wealth of Pteridopytes, their distribution, endemism, medicinal
importance and sustainable utilization in Thiruvananthapuram district by conducting field

study and by referring published data.

MATERIALS AND METHODS

Study Area:

Thiruvananthapuram, with a total area of 2191.92 sq. Km is one of the smallest districts in

the southernmost part of Kerala lies between north latitude 8°17' 50" and 8° 53' 42" and east
longitudes 76° 40' 24" and 70° 17' 00". It is bounded in east by Tirunelveli district and south

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