First Publication: January, 2016
M. K. Bhattacharya & Kathakali Nath
Dept. of Botany & Biotechnology, Karimganj College, Karimganj, Assam
Pteridophytes, the first vascular land plants could not attract much attention of the botanists in spite of the fact that they offer beautiful foliage and interesting adaptive features. They are plants with a regular alternation between larger sporophytes and generally inconspicuous, gametophytes, which may be free-living making possible separation of a lifecycle of an individual plant by time and space, a life which can be regarded as two in one or rather one in two. They offer sporophytes mostly with rhizomes (psilotaceae) or roots (for the first time in plant kingdom), stems (represented by a rhizome), and leaves (which may be microphylls or megaphylls). However, the most eventful adaptive feature of the group is development of vascular strands in the stem which exhibited protostelic, siphonostelic, solenostelic, dictyostelic, or polystelic conditions. They may be homosporous or heterosporous with characteristics which fulfilled preconditions for appearance of seed plants.
This dominant plant group of carboniferous period is now represented by 12000 extant species which are no doubt cosmopolitan but show a well-marked preference for humid tropics. In India there are more or less 1000 species of pteridophytes which are distributed in northern and southern states. Assam presents about one third (350) of Indian total, of which more or less 50% share is claimed by Barak Valley (southern Assam).
The new molecular data shows that Psilotaceae and Equisetaceae, along with the Ophioglossaceae and Marattiaceae, are better regarded as basal relatives of the true ferns (Osmundaceae onwards), forming a monophylletic group, the monilophytes, more closely allied to the spermatophytes, the seed-bearing gymnosperms and angiosperms than to the lycophytes (Pryer et al., 2001; Smith et al., 2006.). In the present work only ferns of Barak Valley are considered leaving aside the fern allies for a separate volume.
The present work illustrates the composition and importance of the pteridophyte flora of Barak Valley, which is no way poorer than that of other comparable geographic areas and is probably one of the species-rich region for the first vascular land plants in the country.