2011 Volume 62 Issue 1 Pages 15-23
Ligustrum micranthum Zucc. (Oleaceae), a small tree endemic to the Bonin Islands, was examined in the field to clarify its sexual system. In the local populations examined on Chichi-jima, all individuals appeared to be hermaphroditic, having a pistil with an ovary and two stamens. They were divided into two morphological groups, however, one having anthers with pollen (staminate fertile) and the other having anthers without pollen (staminate sterile). Staminate sterile individuals set fruit under open pollination. However, staminate fertile individuals showed various fruit production under open pollination. Five plants of the 19 staminate fertile individuals examined did not set fruit for the two years of our observations. This is the first report of sexual polymorphism in Ligustrum. Such a sexual system in L. micranthum might have evolved within the Bonin Islands.
