Floral development of Nelumbo Nucifera (Nelumbonaceae)

The floral development of Nelumbo nucifera was compared with that noted in previous studies of Nelumbo, Nymphaeaceae, and other basal angiosperms. Imp ortant features include developmental evidence of only two sepals, developm ent of an androecial ring meristem, and an apocarpous gynoecium composed of ascidiate carpels that become embedded in an expanded receptacle. Secretor y papillate trichomes cover the stigma and line the stylar canal. The uniqu e apocarpous gynoecium, which lacks a conical residual floral apex, and a g reatly expanded receptacle distinguish Nelumbonaceae from the Nymphaeaceae, as does the distinctive androecial ring. Nelumbo is characterized by polys ymmetric floral development, with some organs originating spirally (petals) and some in simultaneous whorls (stamens and carpels). This pattern of flo ral development, as well as the pattern of carpel closure by secretion, is common in several paleoherbs and eudicots and indicates phylogenetic affini ty between Nelumbonaceae and basal angiosperms. Because of its unique flora l development and anatomy, Nelumbo appears to be an isolated member of the eudicot clade.