FLORAL ORGANOGENESIS OF THE GENERA CULCAS IA AND CERCESTIS (ARACEAE)

The floral development of Culcasia saxatilis, Culcasia tenuifolia, and Cercestis stigmaticus has been analyzed. These two genera possess uni sexual flowers without perianth. In these species, the cylindrical inf lorescence carry male flowers in the upper part and female flowers in the lower part. In C. tenuifolia, the separation between the female zo ne and the male zone is very sharp. There is no intermediate zone. In C. saxatilis and C. stigmaticus, we may observe rudimentary bisexual f lowers between the two zones. In this intermediate zone, flowers locat ed near the male zone possess male appendages more developped than tho se located near the female zone. On the other hand, the flowers locate d near the female zone possess female appendages more developped than those located near the male zone. The results suggest the existence of a morphogenetic gradient in the inflorescence of some species of Arac eae.