Morphology of Bauhinia pollens (Cercidae, Caesalpinioideae, Fabaceae)

The species of Bauhinia L. are variable in their habit, flower, pollen, and fruit morphology. This led several authors to adopt different criteria for the taxonomic delimitation of the genus. With the aid of brightfield, interference contrast, and scanning electron microscopy, the pollen of the 7 Argentinean species has been studied. This analysis has allowed the pollen to be grouped into different types and subtypes: Type 1: 3-zonocolporate, tectate, tectum microgranulate with supratectal spherical rugulate processes = B. microstachya (Raddi) Benth. var. microstachya. Type 2: 3-zonocolporate to porate, microreticulate, semitectum with spinose supratectal processes = B. uruguayensis Benth. Type 3: 4-6-zonocolpate, reticulate, semitectum with geminate supratectal processes; Subtype a: Colpi long and narrow = B. argentinensis Burkart var. argentinensis. B. argentinensis Burkart var. megasiphon (Burkart) Fortunate, and B. bauhinioides (Mart.) Macbr.; Subtype b: Colpi wide and short = B. mollis (Bong.) D. Dietr. var. notophila (Griseb.) Fortunate, B. forficata Link subsp. pruinosa (Vogel) Fortunate & Wunderlin, and B. affinis Vogel. At the same time, a correlation was confirmed between pollen morphology and the infrageneric divisions established by Wunderlin et al. in 1987.