Apostasioid orchids
Apostasia wallichii
Scientific classification
Kingdom:	Plantae
(unranked):	Angiosperms
(unranked):	Monocots
Order:	Asparagales
Family:	Orchidaceae
Subfamily:	Apostasioideae Horan. (1847)
Genera
Apostasia Neuwiedia
Distribution of Apostasioideae

The subfamily Apostasioideae belongs to the orchid family (Orchidaceae).

It is a clade, but there is bootstrap support that it is a sister to the other orchid subfamilies. A bootstrap is a method for evaluating the statistical importance of positions of different branches in a phylogenetic tree (= a treelike structure giving the evolutionary development of organisms).

The apostasioid orchids are the most primitive orchids, with only two genera. Neuwiedia has 3 fertile, abaxial (= facing away from the stem) anthers, while Apostasia has two fertile abaxial anthers and a filamentous staminode (= a sterile stamen).

These primitive features make them, according to some authorities, not true orchids but rather ancestors of modern orchids. However, modern studies (Stern, Cheadle and Thorsch, 1993) point out that the apostasioid orchids are uniquely defined ( = autapomorphous). This makes them unsuitable as models to be the ancestors of the orchids.

[edit] References

• Stern, W. L., V. Cheadle, and J. Thorsch (1993). "Apostasiads, systematic anatomy, and the origins of Orchidaceae". Botanical Journal of the Linnean Society 111: 411–445. doi:10.1111/j.1095-8339.1993.tb01913.x. 
• A. Kocyan, Y.-L. Qiu, P. K. Endress, and E. Conti (August 2004). "A phylogenetic analysis of Apostasioideae (Orchidaceae) based on ITS, trnL-F and matK sequences". Plant Syst. Evol. 247 (3/4): 203–213. doi:10.1007/s00606-004-0133-3.  online pdf.format
• Pridgeon, A.M.; Cribb, P.J.; Chase, M.W. & F. N. Rasmussen (1999): Genera Orchidacearum Vol.1, Oxford U. Press. ISBN 0-19-850513-2

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