The systematic value of pollen morphology in trees and shrubs species of Bauhinia L. (Caesalpinioideae- subg. Bauhinia - sect. Pauletia) occurring in Brazil

Abstract

We analyzed the pollen grains of 30 taxa of the genus Bauhinia L., within five series: Aculeatae (9 species); Acuminatae (1 species); Cansenia (17 species); Pentandrae (2 species); and Perlebia (1 species). The pollen grains were acetolysed, after which they were photographed and analyzed under light microscopy. Non-acetolysed pollen grains were analyzed under scanning electronic microscopy. Characters such as shape, size, exine and aperture constitution were studied. The species were separated by a dichotomous key, which showed pollen grains that were classified as very large; isopolar or apolar; oblate, suboblate, oblate spheroidal or spherical; large or small in terms of the polar area; inaperturate, 3-porate or (3-7)-colpate; and microreticulate or reticulate, with or without supratectal elements (gemmae, bacula, clavae). The variation in pollen morphology confirms the eurypalynous status of the genus Bauhinia.