POLLEN AND NUTLET MORPHOLOGY IN MOSLA (LABIATAE) AND THEIR SYSTEMATICVALUE

An SEM study of pollen morphology in Mosla and the representative spec ies of the allied genera, Collinsonia, Elsholtzia, Keiskea, Perilla, a nd Perillula, reveals that the pollen surface sculpture of Mosla (exce pt M. cavaleriei) and Perilla has discontinuous ridges, while that of the other genera has the suprareticulate ornamentation. The nutlet sur face ornamentation of Mosla and Perilla is also unique. Both pollen an d nutlet morphology suggest that Mosla and Perilla are the most closel y related and highly specialized among these genera. The SEM examinati on of pollen and nutlet of Mosla provides no support to the sectional subdivision in this genus.