Palinologia e taxonomia dos gêneros Elephantopus L., Orthopappus Gleason e Pseudelephantopus Rohr. (Subtribo Elephantopinae, Vernonieae- Asteraceae) ocorrentes no Brasil

Abstract

The elephantopinae subtribe has been targeting a few taxomic and palynology studies it´s needing a reassessment in your limits. Accordingly, the present work aims update and expand the knowledge of 13 species occurring in Brazil through an accurate palynological work, leaf anatomy and taxonomy, promoting division of Elephantopus species of the genera (10 species) Orthopappus (one species) and Pseudelephantopus (two species) besides offering support for subsequent phylogenetic analyzes. The botanical material was obtained by exsiccates deposited in brazilian herbarium and material collected in the field. The pollen grains were treated by acetolytic method and subsequently measured, described, and analyzed by light and scanning electron microscopy. The electron micrographs were obtained from pollen grains not acetolysed, taxonomic analyzes are based on the classical methodology. The leaf anatomy was made by the usual method. The results show mean pollen grains, 3-porate, the exine echinolophate with organized polygonal meshes or not in Elephantopus and Pseudelephantopus, may present disruption in temporal mesh in Elephantopus. In Orthopapus pollen grains are 3-colporate of subequinolofada sexine. The leaf anatomy allowed the separation of E. hirtiflorus and E. riparius through the shape or contour of the midrib (convex-plan) in the other species the outline is biconvex. The species present capitate trichomes biseriate with 8 cells, filamentous trichomes 3-4 cell, and filamentous distal globose or oval cells in E. biflorus, E. micropappus, E. tomentosus and Orthopappus angustifolius. Registered variation in ornamentation of the cuticle may be smooth or striated between species, as well as the presence of pectic substances in the epidermis and parenchyma in drusen. In relation to floral microtypes were considered diagnostic importance of the lobes of the corolla, ranging from glandular, glabrous and penicillate, the latter only in E. hirtiflorus, the apex of the anthers ranging from obtuse, retuso in E. hirtiflorus and apiculate, lancelolado in E. mollis and E. racemosus, the base of the anther varied between sagittate, caudate smooth E. riparius and E. tomentosus caudate and E. riparius. The macrocaracteres that showed greater taxonomic value were cypsela and pappus, coflorescências of the organization, the number of flowers per chapter and leaf blade. This paper has accepted the segregation of the three genera, based on the characters analyzed