PHENOTYPIC GENDER IN SEX CHANGING DWARF GINSENG,PANAX TRIFOLIUM (ARALIACEAE)

Dwarf ginseng (Panax trifolium L., Araliaceae) is a diphasic (“sex changing”) species in which one phase has staminate flowers and the other has hermaphroditic flowers. In order to determine the relative allocations of the hermaphroditic gender phase to male and female functions,variation in population gender phase ratios, pollen production and viability, and ovule and seed production were documented. Gender phase ratios are highly male-biased. Dwarf ginseng is self-compatible, and both gender phases have viable pollen capable of effecting fertilization. Males produce more flowers and more viable pollen per anther than hermaphrodites. The phenotypic gender of hermaphrodites is extremely female-biased; it is likely that hermaphrodites function essentially as females. Sexual selection may have a role in the evolution and maintenance of differences between the gender phases in allocation to male function.