AN ASSESSMENT OF POLLEN MORPHOLOGY IN THE GENUS VITEX L (LABIATAE)

Pollen grains of Vitex (Labiatae) a large pantropical genus with a few temperate species, are examined by light microscopy, SEM and TEM. All grains are elliptic and tricolpate. However, exine surface sculpture varies between taxa. Two main morphological groups are recognized: the first is tectate simple-perforate to tectate perforate-fenestrate (wi th perforations anastomosing); the second tectate micro-reticulate/rug ulate with micro-perforations in valleys between muri (the latter form is found in Madagascar taxa which have a long corolla tube). Pollen o f the commonly cultivated Vitex negundo is unusual in having supra-rug ulate, often collapsed grains. Polar and equatorial sizes are included and the possible taxonomic significance of the morphological differen ces discussed.