Pollen morphology ofcrossandrasalisbury andcrossandrellac. b. clarke (acanthaceae: acantheae)

Open Access
Publisher Website
Google Scholar
Abstract
The pollen of 30 species, five subspecies and one possible hybrid of Crossandra Salisbury, together with that of one species of Crossandrella C. B. Clarke, was examined with light microscopy, scanning electron microscopy and selectively with transmission electron microscopy. A remarkable range of exine stratification was discovered and this was used as the basis for the delimitation of six pollen types. Pollen Types I-V are found in Crossandra and Pollen Type VI in Crossandrella. The relationships between these Pollen Types and the sectional classification of Crossandra are discussed. The pollen of one species, Crossandra flava, was found to be highly variable, with both ridged and unridged pollen, and some abnormally shaped sterile pollen grains. Three evolutionary trends are recognised in the pollen morphology of Crossandra and Crossandrella and these are discussed, together with functional aspects.