This is a list of genera in the orchid family (Orchidaceae), originally according to The Families of Flowering Plants - L. Watson and M. J. Dallwitz. This list is adapted regularly with the changes published in the Orchid Research Newsletter which is published twice a year by the Royal Botanic Gardens, Kew. The most up to date list of accepted; genera, natural nothogenera, species and natural nothospecies with their synonyms can be found on the World Checklist of Selected Plants Families Search Page published by the Royal Botanic Gardens, Kew. This list is reflected on Wikispecies Orchidaceae and the new eMonocot website Orchidaceae Juss. This taxonomy undergoes constant change, mainly through evidence from DNA study. Orchids were traditionally defined by morphological similarity (structure of their flowers and other parts). However, recent changes to nomenclature have been driven primarily by DNA studies and also by re-examination of herbarium specimens. This has led to a reduction of genera and species as well as re-circumscription of subfamilies, tribes and subtribes. Orchid taxonomy is still being revised and each year about another 150 new species are being discovered. The list of genera alone currently stands just short of 1000 entries. From a cladistic point of view, the orchid family is considered to be monophyletic, i.e. the group incorporates all the taxa derived from an ancestral group. The taxonomy of the orchids is explained on the page Taxonomy of the orchid family. Subfamilies There are five recognized subfamilies: Apostasioideae (two genera, Neuwiedia and Apostasia) Cypripedioideae (five genera: Cypripedium, Mexipedium, Paphiopedilum, Phragmipedium and Selenipedium Epidendroideae (has 15,000 species in 576 genera) Orchidoideae (7 tribes and 3,630 species; has 2 subclades with tribes Orchideae and Diseae then the other has tribes Cranichideae, Chloraeeae and Diurideae) Vanilloideae (15 genera and about 180 species: Tribe Pogonieae (77 species; Cleistes, Cleistesiopsis, Duckeella, Isotria, and Pogonia) also Tribe Vanilleae (with 172 species; Clematepistephium, Cyrtosia, Epistephium, Eriaxis, Erythrorchis, Galeola, Lecanorchis, Pseudovanilla and Vanilla) Genera A Aa Abdominea Aberrantia (Luer) Luer (synonym of Acianthera Scheidw.) Acacallis Lindl. (synonym of Aganisia) Acampe Acanthophippium Aceras Aceratorchis Acianthera Scheidw. Acianthus Acineta Lindl. Ackermania Acoridium Acostaea Schltr. Acriopsis Acrochaene Acrolophia Acrorchis Ada Adamantinia Van den Berg & C.N.Gonç Adenochilus Adenoncos Adrorhizon Aerangis Aeranthes Aerides Lour.: fox brush orchid Aganisia Aglossorrhyncha Agrostophyllum Alamania Alatiliparis: new genus with 2 species, discovered in Sumatra, Indonesia Altensteinia Amblyanthe Amblostoma Scheidw. Ambrella Amerorchis: round-leaf orchid Amesiella Amoana Amparoa Amphigena Anacamptis Rich. Anacheilium