Pollen morphology of Acalypha L. (Euphorbiaceae) with emphasis on Brazilian species from Bahia

We investigated the pollen morphology of eight species of Acalypha occurring in Bahia State, Brazil. Flower buds were collected from specimens deposited in the CEPEC and HUEFS herbaria. Pollen samples were acetolyzed and analyzed using both light and scanning electron microscopy. The pollen grains examined using optical microscopy were found to be small and brevicolporate, with three to six apertures and elevations and fastigium, and had a psilate to scabrate exine. Scanning electron microscopy revealed the presence of supratectal elements and Ubisch bodies, and evidenced three pollen types based mainly on exine ornamentation: microrugulate-scabrate (slightly rugulate-scabrate), areolate-rugulate, and microechinate. This study provides new data and new interpretations of pollen morphology for the genus Acalypha, with comments on the palynological relationships between Acalypha and its sister group Mareya, and the next most closely related genus (Spathiostemon).