DEVELOPMENT OF POLLEN GRAIN AND ANTHER WALL OF Tigridia pavonia (L.F.) D.C.
Tigridia pavonia (Iridaceae), is a monocot native to the Americas, little is known about its reproductive biology. The aim of this work was to study the ontogeny of pollen grains and the anther wall. The first stages of floral development occur within underground bulbs that were obtained from wild plants in the State of Mexico. The anthers at different stages of development were processed for optical microscopy and scanning electron microscopy. Tetrahedral and isobilateral tetrads occurred during microsporogenesis, and meiosis I occurred within the bulb; this process is asynchronous in the same anther, in the same flower and in the same inflorescence. The tapetum is secretory with protuberences at the tetrad stage. Pollen grains are bisulcate, curvimurate and they dispersed in clusters joined by pollenkitt and viscin threads, an uncommon feature in monocotyledons. The pollen exine is reticulate intectated, heterobrocated and curvimurate, fused pili, and numerous basal spicules in the form of granules. At anthesis, pollen grain still binucleated. The anther wall begins with a protodermis and parietal primary cells, were the subepidermal cells showed periclinal division, forming the endotecio and the intermediate strata (3-4), later these cells collapse and the endotecio develop helicoidal and reticular cell wall thickening. The epidermis of the anther has anomocitic stomata and reticulated cuticle, each theca develops a dorsal rib with epidermal cells with raised walls. This is the first anatomical description of pollen and anther development for the tribe Tigridieae and for T. pavonia.