POLLEN MORPHOLOGY IN ALOE (AROACEAE)

Pollen grains of 36 species of Aloe (Aloaceae), a large and essentiall y Old World genus, were examined by light and scanning electron micros copy. All grains were monosulcate with a well-defined, acutely ended s ulcus, bordered by a narrow, unsculptured zone of the exine. The tectu m was generally smooth, microreticulate-heterobrochate and microreticu late, tending rewards becoming tectate-perforate. Infrageneric differe nces occurred in the size of the grains and in the shape and dimension s of tectal perforations, with concomitant variations in muri width. T hree pollen types based on tectal characters were distinguished. The t axonomic usefulness of observed pollen morphological characters was ev aluated in the light of Reynolds's (1950) classification of the genus.