Hermaphroditism and dichogamy in Stilbocarpa polaris (Araliaceae) on Campbell Island

Abstract

Since its scientific discovery in 1844, the breeding system of Stilbocarpa polaris (Araliaceae) has been described as polygamo-dioecious with either unisexual or hermaphroditic and female flowers. A short study of flower sex expression, on subantarctic Campbell Island, found evidence that all flowers are cosexual, protandrous and strictly dichogamous, such that whole inflorescences are either presenting pollen or stigmas. Circumstantial evidence also suggests that S. polaris is self-compatible but self-fertilisation would be largely avoided by this synchronous dichogamy. Pollination is most likely effected by small diptera which congregate on inflorescences. © 2012 The Royal Society of New Zealand.