Abstract
16 taxa coming under 10 families occurring in the Mangroove forests of Tamilnadu, have been studied cytologically, of which first record of chromosome number has been made in lanceolate leaf type of Sesuvium portulacastrum, Rhizophora candelaria, Ceriops roxburghiana, Bruguiera conjugata, Avicennia marina, Suaeda maritima, S. monoica, Arthrocnemum fruticosum, Aegiceros corniculatus and Ilysanthes tenuifolia.
n=18 may be the common primary basic number of the vegetation and from this the basic numbers 8, 9, 11, 12 and 15 should have arisen by decrease of chromosome numbers and the basic numbers n=19, 20, 22 should have originated by increase of chromosome numbers.
Smaller size of chromosomes and mostly chromosomes with submedian and subterminal constrictions are the other advanced cytological characters of the mangroove vegetations studied.
