Pollen and seed morphology of Barleria L. (Barlerieae: Ruellioideae: Acanthaceae) of Yemen

A study of pollen and seed morphology of Barleria L. of Yemen that comprises nine species has been carried out. This study utilizes the pollen and seed micromorphological characters to show its taxonomic significance within the genus, and the species studied B. acanthoides, B. aculeata, B. orbicularis, B. parviflora, B. prionitis, B. ventricosa, B. proxima, B. tetracantha and B. bispinosa. Pollen grains are spheroidal, tricolporate, short aperture and circular endoaperture are present. Measurements of lumina, columellae, apocolpium, granules and exine thickness are useful to distinguish species within the genus. Seed coat ornamentation provides a significant character to distinguish this genus which has long or short, straight or twisted and wooly hygroscopic hairs which differ from those of other genera in the family.