The pollen morphology of 31 species (50 accessions) of Ruellia L. is d
escribed and illustrated, based on examination with light, scanning an
d transmission electron microscopy. The pollen is spherical, coarsely
reticulate (except for two species which are clavate), usually 3-porat
e, rarely 5-porate or 3-colporate. Pollen is a good diagnostic charact
er for Ruellia species. The pollen characters are discussed with regar
d to species relationships and functional significance.