Extra-Amazonian Brazil comprises a region with vegetation formations representing the Caatinga (drylands), Cerrado (neotropical savanna), Atlantic Forest, Pantanal (seasonally inundated) and Pampa (grassland) biomes with high species richness. Twenty-five species of Cestrum occur in this region, of which 23 are palynologically examined here with the purpose of contributing to the taxonomy of the genus: C. axillare Vell., C. bracteatum Link & Otto, C. corcovadense Miers, C. corymbosum Schltdl., C. euanthes Schltdl., C. gardneri Sendtn., C. intermedium Sendtn., C. latifolium Lam., C. mariquitense Kunth, C. martii Sendtn., C. montanum Miers, C. obovatum Sendtn., C. parqui L’Hér., C. pedicellatum Sendtn., C. reflexum Sendtn., C. retrofractum Dunal, C. schlechtendalii G. Don, C. strictum Schott ex Sendtn., C. strigilatum Ruiz & Pav., C. subpulverulentum Mart., C. subumbellatum Vignoli-Silva & M. Nee, C. tubulosum Sendtn. and C. velutinum Hiern. The pollen grains were acetolyzed, measured, described and photomicrographed using light microscopy; non-acetolyzed grains were analyzed using scanning electron microscopy. The pollen grains were found to be medium and/or large, isopolar, subprolate, oblate-spheroidal, spheroidal, suboblate or prolate-spheroidal in most species, 3-colporate, endoaperture lalongate, fastigiate, rugulate, rugulate-striated or rugulate-areolated and psilate, or not, in determined regions. The results indicated that the taxa studied demonstrated sufficient pollinic heterogeneity of their shapes, aperture attributes and sexine ornamentation to enable palynological characterization of the species.

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