Vascularisation de la fleur de Lysichitum camtschatcense (Araceae)

Abstract

Based on the floral vascular system, the authors analyse the problem of pseudomonomery and the intergeneric relationships within the Calloideae. The whitish hermaphrodite flowers have a perigone formed of four tepals. The androecium is composed of four stamens, but the structure of the gynoecium is more variable. Thus, among the flowers studied we observed bilocular ovaries with one ovule per cavity, bilocular ovaries where one of the two cavities had failed to develop, and unilocular ovaries with one or two ovules. The study of the vascular system shows that all of these gynoecia are composed of two carpels. In each of them we observed two dorsal bundles and two complex ventral bundles, each of these formed of two simple ventral bundles belonging to different carpels. Concerning the unilocular gynoecium, with one or two ovules, the presence of the bundles of the abortive carpel indicates that this gynoecium is pseudomonomerous. It is with the genus Symplocarpus that Lysichitum shares the greatest number of characters; their floral characteristics are particularly similar. In a previous study it was supposed that Symplocarpus, which has a unilocular ovary, was really monomerous. Now, the latest analyses of the flower of Lysichitum force us to reconsider this interpretation. The distribution of the floral characters indicates that Symplocarpus is advanced in comparison with Lysichitum.