Embriología de Pachycereus militaris (Audot) Hunt (Cactaceae)

This is a contribution to the embryology of cacti and to the definition of their reproductory structures. The development of anthers, ovules and seeds of Pachycereus militaris is described. The type of development of the anther wall is monocotyledonous. This may have taxonomic importance above the family level. The endothecium is formed by a single stratum and the pollen grains are tricolpate, spinulate and punctitegilate. A lineal triad of megaspores was observed. The functional megaspore is the chalazal one. It is proposed that the term campylotropous should be uti lized for describing the ovule type, while the term circinotropous should be reserved for the funicle. In contrast to the stated by other authors, this study suggests that the seeds of Pachycereus militaris should be considered as non-albuminous and non-perispermous.