Architectural Effects on Floral Traits in Sedum praealtum Dc. (Crassulaceae) in Mexico

Abstract: Morphological and functional characteristics of flowers have been the primary criterion for traditional plant taxonomy and systematic classification because of their assumed constancy among individuals within a population. The effects of resource competition and pollen limitation from those of inflorescence architecture were separately studied during flowering season of the species to investigate patterns of investment allocation and fruit set among flowers within inflorescences of Sedum praealtum. I found that architecture was primarily accountable for the variation observed in reproductive traits of flowers within inflorescences. Specifically, the S. praealtum inflorescences exhibit a proximal to distal investment allocation sequence from female-biased to male-biased flowers, whereas the observed differences in fruit set were at least partially attributable to pollen limitation in distal-positioned flowers. Given the opportunity for different contributions of female and male functions to reproductive success, potential gender specialization of flowers at different positions within the inflorescence are discussed.