Inhibition of self pollen germination in Senecio vulgaris L.

Abstract

Experiments are described which show that Senecio vulgaris L. (common groundsel) possesses two independent systems which inhibit the germination of self pollen. In one system, self but not cross pollen tube penetration of the stigma is prevented in the ray florets of a proportion of radiate plants. In the other system, cross pollen adheres in greater quantity than self pollen 24 hours after application to disc floret stigmas of both radiate and non-radiate plants. The possible origins of these systems, and their functions in natural populations, are discussed.