Responses of Floral Traits and Increase in Female Reproductive Effort to a Simulated Environmental Amelioration in a Hermaphrodite Alpine Dwarf Shrub, Sieversia pentapetala (Rosaceae)

Abstract

This report presents empirical data for variations of floral traits and “femaleness” (dry-weight allocation to the female organs) under a simulated environmental amelioration by using open-top chambers (OTCs) in a hermaphrodite alpine dwarf shrub Sieversia pentapetala (L.) Greene, in the Tateyama Range, central Japan. The results showed that gynoecium, peduncle, and flower weight in OTC-manipulated shoots were significantly heavier than those in controls. As a result, “femaleness” showed a significantly higher value in the OTC-manipulated shoots as compared to the controls. Moreover, gynoecium weight was significantly positively correlated with leaf mass (per flowering shoot), while androecium weight was not, suggesting a higher resource requirement for reproduction through the female function. Thus, it was experimentally demonstrated that the gender of S. pentapetala flowers changed from male-biased to female-biased as leaf mass increased under less stressful conditions.