XVI International Botanical Congess

Tristyly involves three different forms of flowers that differ reciprocally in the heights of stigmas and anthers within flowers. Heterostylous species also demonstrate pollen and stigma polymorphisms. Using scanning electron microscopy, we quantified pollen polymorphism in tristylous Lythrum salicaria. Pollen differed significantly in diameter and length of pollen grains, and the length of colpi and pseudocolpi by morph, stamen types and their interactions. A discriminant function analysis separated one group of pollen from the other two groups, based on the canonical scores of measurements of pollen morphology. The pollen polymorphism was found to be complimentary to that of the stigma which may play a functional role in self-incompatibility mechanisms.