Pollen viability and size in British Centaurium Hill and Gentianella Moench (Gentianaceae) taxa

Abstract

A survey of pollen viability and size in British Centaurium and Gentianella (Gentianaceae) taxa has been undertaken on herbarium specimens using Alexander’s Stain as a test for potential pollen viability. The material was selected mainly from Britain with some European material to give a wider context. The mean pollen viabilities for Centaurium species ranged from 76 to 89%, whilst the hybrids were significantly lower. The one sample of C. latifolium analysed had 94% pollen viability. The mean pollen viabilities for the Gentianella species ranged from 59 to 83% and although the hybrids had slightly lower viabilities they were not significantly so. The diploids C. scilloides and C. tenuiflorum had smaller pollen than tetraploid Centaurium species. Gentianella germanica had larger pollen than other Gentianella species, but pollen of the hexaploid G. uliginosa was not larger than the tetraploid species. Variation in viability and size within species, coupled with the high viability of hybrids, means that pollen characters are unlikely to provide consistent indicators of hybridisation.