Abstract
Thirty-one species and varieties of 8 North-Indian Convolvulaceous genera were investigated. Normal diploid like meiotic behaviour was evident in most of these. Polyploid nature of Ipomoea batatas and some desynaptic bivalents in Merremia aegyptia accounted for aberrant meiosis. Some desynaptic bivalents were also observed in I. bonanox, Porana paniculata and Calystegia hederacea.
Ipomoea chryseoides (n=15), I. mutabilis (n=15+O-1B), I. dichroa (n=15), I. palmata (white flowered type n=15+1B) and Argyreia campanulata (n=14) represent first chromosome counts for these species. Lowest and highest chromosome numbers n=9 and n=45 were encountered in Jacquemontia pentantha and Ipomoea batatas respectively.
Poor incidence of polyploidy may either be due to a meagre cytological coverage or the secondary nature of the high basic numbers met in the family. Aneuploidal relationship of the different species/genera is evident. Importance of aneuploidy and polyploidy in the evolution of Convolvulaceae is discussed.
Morphological variability in Ipomoea aquatica, I. eriocarpa, I. fistulosa, I. palmata and I. pestigridis seems to be correlated with the cytological features.
