Pollen morphology of some Cuban Guettarda species (Rubiaceae: Guettardeae)

Pollen grains of 19 taxa of the genus Guettarda (Rubiaceae: Guettardeae) were studied using light microscopy, scanning electron microscopy (9 species), and fractured pollen grains (7 species). Most of the species have suboblate to oblate spheroidal, small to medium-sized grains with reticulate, microreticulate, perforate or foveolate exine. There is a great variability in the morphology of ectoapertures and endoapertures. Three pollen types are established, mainly based on differences in ectoapertures and sexine ornamentation.