Pollen morphology of the subfamily Aurantioideae (Rutaceae)

The Aurantioideae is one of seven subfamilies of the Rutaceae consisting of two tribes. the Clauseneae, containing five genera, and the Citreae, with 28 genera. Each tribe contains three subtribes. The pollen morphology of th e subfamily Aurantioideae is described;Ind illustrated for the first time b ased on light and scanning electron microscopy. Five pollen types have been recognised in the subfamily, based mainly on aperture number and exine orn amentation. The pollen grains show a high degree of intergeneric variation. Pollen grains of Clauseneae are 3-colporate, microstriate or microstriato- reticulate, whereas pollen grains of Citreae are almost always 4/5 colporat e with exines varying from microperforate to coarsely reticulate. Congruenc e between pollen types and the currently accepted classification is discuss ed, as well as the systematic implications of pollen morphology for the sub family.