Pollen Morphology of Spiradiclis Bl. (Rubiaceae)

Sixteen pollen samples from 11 species and 1 form of the genus Spiradiclis Bl. were examined under LM, SEM and TEM . Results revealed that pollen grains of Spiradiclis were single, small or medium-sized, spheroidal to prolate, radial symmetry, usually 3-colporate, sometimes 4-colporate, and with perforated tectate. The exine consisted of inconsistent perforated tectate, columellae and foot layer. Both exine and intine wereobvious. Pollen dimorphism and bubble-like protrusions were found in Spiradiclis. Pollen characters of Spiradiclis have little value for distinguishing infra-genus taxa, but they can provide much information in the phylogeneticrelationships among species, e.g., the taxon having same pollen is more advanced than that having dimorphic pollen.