Abstract
Sexual dimorphism in Arenaria merckioides var.chokaiensis was investigated from morphological and reproductive points of view. The variety was found to be gynodioecious with hermaphrodite and female plants occurring in natural populations. Hermaphrodite flowers are characterized by their larger petals, longer filaments and larger anthers that contain viable pollen grains, and protandrous flowering habit. Female flowers, on the other hand, have smaller petals, larger stigmas and abortive anthers that contain no pollen grains. In addition, the stigmas of the female flowers mature earlier than stigmas in hermaphrodite flowers. The larger stigmas appear to increase the likelihood of pollen trapping in female flowers.
