BIOGENIC SILICA IN SOME PTERIDOPHYTES

Biogenic silica is being deposited in the form of flat sheets over the epidermal cells or three dimensional infillings of cavities within and between the cells of certain plants. These silica bodies are called phytoliths which are formed due to the uptake of dissolved monosilicic acid in soil water during growth of the plants. In the present study we have investigated the silica deposition pattern in certain Pteridophytes viz., Lycopodium clavatum L., Selaginella bryopteris L., Actiniopteris australis (L. Fil.) Link, Adiantum caudatum
L., A.philippense L., A. peruvianum KL., A. venustum Don, Cyathea gigentea(Wall.ex Hook.) Holtt., Doryopteris sagittifolia (Raddi) J. Sm., Drynaria quercifolia(L.) J. Sm, Gleichenia microphylla R.Br, Hemionites arifolia (Burm.) Moore, Lygodium flexuosum (L.) Sw. and Pteris vittata L. These Pteridophytes show silicified epidermis, stomata trichomes, sclereids and tracheids. Silica is also deposited in the cells of the sporangium and sporoderm of spores of certain ferns. Silicified casts of epidermal, palisade and mesophyll cells of pinnules of certain ferns are also reported.
Silica deposition is very characteristic in some Pteridophytes which are very important for the reconstruction of the early history of these plants. The importance of silica deposition in Pteridophytes is also emphasized in this paper.