staminode. Subfamily Cypripedioideae: monophyletic - two fertile diandrous anthers, a shield-shaped staminode and a saccate (= pouch-like) lip. Subfamily Orchidoideae: monophyletic - one fertile, monandrous, basitonic anther. (Subfamily Spiranthoideae): now accepted as nested within a more broadly defined Orchidoideae as the sub-tribe Spiranthinae of the tribe Cranichideae. Subfamily Epidendroideae: monophyletic - includes almost 80% of the orchid species; 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: monophyletic - an ancient clade now recognized as a distinct subfamily. Their phylogenetic position had long been controversial. Cladistically, the interrelationships of these subfamilies can be shown in a phylogenetic tree as follows: Subfamily Apostasioideae The subfamily Apostasioideae belongs to the orchid family (Orchidaceae). All well-sampled molecular phylogenetic studies have produced strong bootstrap support for its position as sister to a clade consisting of the other orchid subfamilies. Bootstraping is a method of resampling for quantifying the statistical support for nodes in a phylogenetic tree (= a treelike diagram showing the evolutionary diversification of organisms). The apostasioid orchids are the most primitive orchids, with only two genera. Neuwiedia has three fertile, abaxial (= facing away from the stem) anthers, while Apostasia has two fertile abaxial anthers and a filamentous staminode (= a sterile stamen). Plants with mealy or paste-like pollen, which ordinarily are not aggregated into pellets, called pollinia, with two or three fertile long anthers, leaves with sheathing bases, elongated staminode and labellum similar to the petals. These primitive features make them, according to some authorities, not true orchids but rather ancestors of modern orchids. However, more recent studies indicate that many of their differences with the other orchids were not inherited from a common ancestor with orchids, but arose within the stem group of apostasioid orchids. Apostasia Blume, included Adactylus Rolfe and Mesodactylis Wall. Neuwiedia Blume Subfamily Cypripedioideae 6 genera with about 115 species, mostly terrestrials or lithophytes: Tribe Cypripedieae Subtribe Cypripediinae Cypripedium Lindl., included Arietinum Beck, Calceolaria Heist. ex Fabr., Calceolus Nieuwl., Ciripedium Zumagl., Criogenes Salisb., Fissipes Small, Hypodema Rchb., Sacodon Raf., Schizopedium Salisb., Stimegas Raf. Subtribe Paphiopedilinae Paphiopedilum Pfitzer, included Cordula Raf. and Menephora Raf. Tribe Mexipedieae Subtribe Mexipediinae Mexipedium V.A.Albert & M.W.Chase Tribe Phragmipedieae Subtribe Phragmipediinae Phragmipedium Rolfe, included Phragmopedilum Pfitzer, Uropedium Lindl. Tribe Selenipedieae Subtribe Selenipediinae Selenipedium Rchb.f. Others × Phragmipaphium hort. Subfamily Epidendroideae This is the largest subfamily,