Taxonomy of The Orchidaceae - Taxonomy

Taxonomy

The orchid family (Orchidaceae) is subdivided in several subfamilies, and then in tribes, subtribes, alliances and then genera.

According to Dressler, there are 5 subfamilies, 22 tribes, 70 subtribes, about 850 genera and about 20,000 species in this family.

The following subfamilies are recognized:

• Subfamily Apostasioideae: monophyletic - the most primitive orchids: 3 fertile anthers or two fertile anthers and a filamentous staminode.
• Subfamily Cypripedioideae: monophyletic - 2 fertile diandrous anthers, a shield-shaped staminode and a saccate (= pouch-like) lip.
• Subfamily Orchidoideae: single, fertile monandrous, basitonic anther.
  • (Subfamily Spiranthoideae): nested within a more broadly defined Orchidoideae
• Subfamily Epidendroideae: includes almost 80% of the orchid species; monophyletic; orchids with an incumbent to suberect ( = ascending towards the edges) anther.
  • (Subfamily Higher Epidendroideae (formerly Vandoideae): specialised clade within a more broadly defined Epidendroideae
• Subfamily Vanilloideae: an ancient clade now recognized as a distinct subfamily. But, from a molecular point of view, it is rather a sister to subfamily Epidendroideae + subfamily Orchidoideae. This subfamily is a branch at the basal dichotomy of the monandrous orchids.

As the Genera Orchidacearum (Pridgeon, A.M., Cribb, P.J., Chase, M.A. & Rasmussen, F.; Oxford Univ. Press.) will only be completed in 2006-2007, and changes in taxonomy of orchids are so frequent, the following taxonomy still follows largely the system of Robert Louis Dressler.

Cladistically the interrelationships of these subfamilies can be shown as follows: