Diversity and taxonomic value of stigmatic surfaces in Begoniaceae: SEM analysis

The literature does suggest that morphology and arrangement of stigmatic papillae in Begoniaceae might supply diagnostic characters for the discrimination of taxa. To verify this statement the stigmatic surfaces of 65 well-documented species were studied by light and scanning electron microscopy. At least 16 different morphotypes, which could be classified into five groups, were recognized among the, always unicellular, papillae. Some morphotypes were found to be diagnostic at the species level, and in a few cases the taxonomic identity of sections is underlined by the presence of a singular papilla group. It is concluded that in spite of a remarkable variation in detail the overall morphology is very homogeneous and consistent and in general not suitable for sectional delimitation.