Pollen morphology of eight species of stemodia (plantaginaceae) from South America

Abstract

The pollen morphology of eight species of Stemodia L. (Plantaginaceae) was analysed with the aim of refining the taxonomy of this genus. The pollen grains were examined with both light and scanning electron microscopes. The pollen grains are spheroidal, sometimes prolate-spheroidal, small, with a subcircular or subtriangular amb, 3- or 4-colporate and with a long colpus that reaches the poles, defining a small, circular to slightly lalongate apocolpium with irregular margins. The exine is tectate, foveolate or microperforate, 1 mm thick and uniform. The species of Stemodia analysed here exhibit morphological homogeneity, which suggests that the genus is stenopalynous.