Resumen

RAYMUNDEZ U, María B.; ESCALA J, Marcia  y  XENA DE ENRECH, Nereida. Microsporogenesis in Hymenocallis caribaea (L.) Herb. (Amaryllidaceae). Acta Bot. Venez. [online]. 2008, vol.31, n.2, pp.409-424. ISSN 0084-5906.

An embryological investigation was undertaken for the first time in a member of the genus Hymenocallis, to describe the microsporogenesis in Hymenocallis caribaea. Meiosis takes place when flower buds are still inside the bulb. Microsporogenesis follows a successive type, common in monocots. The process is asynchronous between buds of the same inflorescence (undeterminate or acropetal), anthers of the same flower, and between the apex and the base of each anther (basipetal). Anthers have stomata, the tapetum is ameboid, or periplasmodial, and the endothecium doesn’t develop wall thickenings, contrary to what happens in most family representatives. Tapetum invades anther cavity early and produces pollenkit, a yellowish lipid secretion which is deposited over the mature pollen grains giving them adherent properties. When released from tetrads, microspores are uninucleate and show an undeveloped pattern of wall sculpturing. Pollen grains are monosulcate as in most monocots; the exine shows a dense sculpturing pattern at the ends and a loose reticulum at the central zone. At the time of anther dehiscence, pollen is binucleate, a condition which is considered ancestral within the angiosperms as is the presence of stomata in the anthers.

Palabras clave : Amaryllidaceae; embryology; Hymenocallis; microsporogenesis; pollen.