The gender role of flowers of broad leaved Helleborine, Epipactis helleborine (L.) Crantz (Orchidaceae)

Pollen import and export were assessed for a population of Epipactis helleborine (L.) Crantz. It was found that rates of pollen import and export were positively correlated with the number and density of open flowers borne by an inflorescence. For a given inflorescence size, pollinium export always exceeded pollinium import. It appears that the processes of pollen export and import are temporally disjunct, suggesting that a high level of cross-fertilization occurs in this species. These results are discussed in the light of current sexual resource allocation theory. It is suggested that secondary floral characters have evolved primarily in response to selection for improved levels of pollen export. Thus, in this hermaphrodite angiosperm, secondary floral characters are predominantly male in function.