Acta Phytotaxonomica et Geobotanica 52(1): 115-124 (2001)
Dimorphic Nature in Stigma-Anther Separation of Prunus nipponica (Rosaceae)
SATOKO HIRATA, TAKASHI SUGAWARA

Stigma height, anther height and stigma-anther separation were studied to examine their dimorphic nature in two populations of Prunus nipponica occurring in sub-alpine zone of Mts. Norikura and Utsukushigahara, central Honshu of Japan. The stigma and anther heights considerably varied among the plants and each of the characters showed normal frequency distributions within populations. However, stigma-anther separation showed a bimodal distribution. Based on this floral character the populations concerned were tentatively divided into two discrete floral morphs: long (L)-styled morph and homo (H)-styled morph. Each of the two morphs was highly constant within a plant and did not change its floral nature for over two years. Artificial pollination experiments indicated that the two morphs were strongly self-incompatible and crosses between the same morphs (HxH or LxL) produced seeds in higher percentage. These results suggest that the dimorphic nature in P. nipponica does not exhibit an ordinary heterostyly but may be regarded as an example of herkogamous polymorphism. We briefly discuss on the possible adaptive significance of dimorphic natures of the flowers exhibited by P. nipponica.

Heideman: Sexual Affinities of Prunus americana (1895)