Megasporogénesis y megagametogénesis en hymenocallis caribaea (l.) Herb. (amaryllidaceae) y algunas características de su desarrollo seminal

the main objective of the present research was to characterize the processes of megasporogenesis and megagametogenesis in hymenocallis caribaea and some characteristics of its seed development. to achieve it, there were followed the anatomical methodology suggested by johansen (1940) for embryological purposes. ovules of h. caribaea are bitegmic and pseudocrassinucelate. outer integument rests undifferentiated until the postfertilization stage and it is profusely vascularized. both integuments form a zig-zag micropile, which is considered evolutionarily primitive. meiosis occurs while flower buds are completely immersed in the bulb. megaspore mother cell origins directly from megasporocite. during megasporogenesis four megaspores are formed and only the one at the chalazal pole remains functional (monosporic type), giving rise to the embryo sac. megagametogenesis follows the polygonum pattern, with eight cells in the mature embryo sac: three micropilar cells (two sinergids and the egg cell), three chalazal cells (antipodes),and two polar nuclei in the center-side of the embryo sac. more than one embryo sac per ovule sporadically occurs, but they do not appear to lead to the formation of more than one embryo per seed. development and differentiation of the ovule of h. caribaea to form a green, fleshy, low weight/volume, profusely vascularized seed, with a rudimentary embryo until its development is well advanced, appears to reflect an adaptation to the particular environment where these plants grow.