Anatomía de la semilla de Tigridia pavonia (Iridaceae)

With methods of light microscopy, histochemical staining and scanning electron microscopy, it was found that the ovule in the seed of Tigridia pavonia (Iridaceae) is anatropous, bitegmic, and crassinucellate. During development, the exotegmen is crushed and the endotegmen persists with tannins in the lumens and in the walls, which also react positively for lignin. The exotesta contains tannins and its outer walls are convex, thickened, and cuticularized. The mesotesta has multiple layers, accumulates abundant lipids, and forms a bulge in the chalaza. The cell walls of the endotesta collapse and accumulate tannins. In the chalaza, a hypostasal cushion contains tannins in the lumens and in the walls, which also react positively for lignin. At the micropylar end of the seed there is an operculum which consists of: a) a slightly crushed exotegmen, b) an endotegmen with cuticular thickenings that are concentric with respect to the micropyle, c) hemispherical deposists of cutin on the anticlinal walls of the endotegmen, and c) a thin layer of endosperm that covers the radicle. During its cellular stage of development, the endosperm has conspicuous transfer walls at the chalazal end next to the nucella. The embryo is small and has a conical cotyledon.