All or nearly all species are
dioecious. Knuth (1904) however cites a report of trees being male in their sex expression when young and female later.
Perianth of one whorl of three largely united segments. Stamens two to thirty, partly or wholly united. The ovary is superior, consisting of a single uniovulate carpel. Species in this genus use secondary pollen presentation (pollen presentation in the flower which does not use an anther), the type of which is (German for ‘pollen-heap’), where pollen is in an exposed heap at the base of the flower. ==Selected species==