The relationships of the Apostasiaceae on the basis of floral anatomy

Abstract

The Apostasiaceae is a small family of limited distribution, with about 15 species altogether, and its affinities have been controversial. The floral anatomy of nine representatives of the family is now known in detail, and its relationships are discussed on the basis of the floral vasculature. The pattern of the vascular supply to the floral organs is very similar to that of the diandrous orchids, showing the undoubted affinity of the Apostasiaceae with the Orchidaceae. The subtribe Cypripedilinae of the Orchidaceae must have evolved directly from the Apostasiaceae.