Comparative developmental morphology of two populations of Ceratophyllum L. (Ceratophyllaceae) and their taxonomy

Developmental morphology of two natural populations of Ceratophyllum inhabiting the waters of Delhi has been investigated under natural conditions and in aseptic culture. Both the populations show an extreme degree of adaptability to hydrophily. The embryo is unusually highly developed and contains 12–14 whorls of leaves and a few lateral buds. The two populations differ significantly in colour and dichotomy of leaf; structure and position of male flowers; number, position and colour of horns on the fruit; stylar length and distribution of sexes. The latter two parameters are probably responsible for the reproductive isolation of the populations, despite their sympatric association. On account of these differences, the two populations are assigned to two distinct species C. demersum L. and C. echinatum Gray, respectively and their taxonomy is discussed; C. echinatum is a New World species not previously recorded from India.