XVI International Botanical Congess
The ovule development in Aylthonia blackii, Barbacenia flava var. flava, Vellozia leptopetala and V. caruncularis were studied. Ovules are anatropous in A. blackii and B. flava var. flava and anatropous to anacampylotropous in V. leptopetala and V. caruncularis, bitegmic and tenuinucellate, dermal in origin, the inner integument develops before the outer and both complete development at anthesis. The inner forms an endothelium and in V. leptopetala the outer integument forms a free strucuture on the side of the funiculus. Both integuments form the micropyle. The nucellus degenerates entirely or almost entirely when the gametophytes mature. Megagametophyte is of Polygonum type and mature some 3-5 days after anthesis. The egg apparatus cells have a strong polarity, the three antipodal cells are ephemeral, the big central cell is strongly vacuolated and the polar nuclei complete the fusion process after fertilization.