Male sterility and reproductive output in distylous Erythroxylum suberosum (Erythroxylaceae)

Distribution of male and female organs on individual plants is diverse. Thus, accurate descriptions of plant sexuality are necessary in order to characterize changes in gender. In this study, we evaluated the level of male sterility and its implication for reproductive output in the distylous species Erythroxylum suberosum A. St.-Hil. We recorded that both thrum and pin plants are partially male-sterile, featuring a range of abnormalities in the androecium. Male sterility of donors acts as an important factor responsible for variation in fruit set. This correlation was found for E. suberosum only between thrum pollen donors and pin recipient plants, indicating that there are differences in individual performance of pollen donors between the two floral morphs. However, male sterility occurs at a low frequency in both morphs, and there is no reproductive compensation, in terms of resource reallocation, for the loss of the male function. Under these circumstances, distyly is expected to be evolutionarily stable in E. suberosum (c) 2006 The Linnean Society of London.