Morfoanatomia comparada dos frutos em desenvolvimento de Vernonia brevifolia Less. e V. herbacea (Vell.) Rusby (Asteraceae)

Abstract

In this work, the morphology, anatomy and ontogeny of the pericarp and pappus of Vernonia herbacea and V. brevifolia were described. Both species are very similar, possessing inferior, bicarpellate, syncarpous and unilocular ovary. In the pericarp formation, none region is multiplicative. The exocarp is uniseriate and recovered by thin cuticle. Long, multicellular and bisseriate non-glandular trichomes were observed, which persisted until maturity; capitate glandular trichomes are caducous. The outer mesocarp is composed of two or three fiber layers in V. herbacea, and only one in V. brevifolia, in both it accumulates prismatic crystals. In both species, the inner mesocarp is parenchymatous. Collateral vascular bundles occur immersed between outer and inner mesocarp. The endocarp is uniseriate, presenting two or three layers in the carpel fusing regions only. In the pericarp apical portion, there is a protuberance at the double pappus insertion, composed by lignified cells, some of them projected peripherally. At the fruit base, there is a carpopodium; in V. herbacea it is bigger and has druses and styloids; in V. brevifolia it is reduced and there is no crystals. At maturity, the pericarp of both species is dehydrated in such way that the cell layers are collapsed, and it is possible to distinguish only some exocarp cells and non-glandular trichomes, the outer mesocarpic fibers and crystals, and the xylem of vascular bundles.