Australian systematic botany vol:18 issue:4 pages:367-382
Complementary to the revision of the genus Spermacoce in the Northern Territory of Australia, pollen morphology of 48 of the 53 native Spermacoce species from the Northern Territory has been investigated by scanning electron and light microscopy. There is considerable variation for most diagnostic pollen characters. The average equatorial diameter ( E) ranges from 10.5 to 41.7 mu m. Grains are invariably corporate with the apertures situated at the equator ( being zonocolporate). The number of apertures varies from 3 to 17. The endoaperture is generally an endocingulum, often with a secondary thinning at the ectocolpus; one species has endocolpi. The sexine is usually perforate, but psilate, foveolate, and ( micro) reticulate patterns were also found. Supratectal elements are present as granules or microspines scattered over the whole surface or confined to a region around the ectoapertures. The inner nexine surface is granular, often with irregular grooves ( endocracks).