OVULE AND SEED DEVELOPMENT OF LACANDONIA-SCHISMATICA (LACANDONIACEAE)

Ovule and seed development is described for Lacandonia schismatica, a species whose androecium is surrounded by the gynoecium. The ovule in each carpel is basal, anatropous, tenuinucellate, and bitegmic. The fe male gametophyte is formed by the micropylar megaspore cell, after a c oenocytic stage of the four megaspore nuclei. The mature female gameto phyte has the normal complement of seven cells and eight nuclei. We pr opose a new type of female gametophyte development on the basis of the coenocytic stage of the tetrad, the cellularization of the tetrad, an d the survival of the micropylar spore. At seed dispersal time, the em bryo has similar to 10-20 cells. Endosperm development is of the nucle ar type. At maturity, endosperm cells show starch and protein inclusio ns as well as polysaccharides in their thick walls. The seed coat is f ormed from the outer integument; the inner one disappears. The exotest a contains tannin. The fruit (achene) wall is two-layered. The maturat ion of the fruits in a flower is synchronous, and they separate from t he receptacle for dispersal.