Pleurothallis
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| Bonnet Orchid
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Species
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More than 1200, see text
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Pleurothallis R. Br., 1813 is a huge genus of orchids which contains more than 1,200 species - the second largest in the Orchidaceae after Bulbophyllum.
The genus name is derived from the Greek word 'pleurothallos', meaning 'riblike branches'. This refers to the rib-like stems of many species.
It is a completely New World group and occurs from the southeast United States down into the tropics of South America, with most species in the high Andes chain of cloud forest in Colombia. They grow in dry or wet, tropical or temperate climates.
As a group they show a huge range in vegetative form, terrestrial or epiphytic, and can be found as tall cane-like plants a metre or so high, clumped or trailing, pendent or climbing, erect or creeping, tufted and tiny, delicate moss-like species that can grow on the thinnest of twigs. But they have one common denominator : they all have two pollinia.
They have reduced their pseudobulbs and instead, some species have thick succulent leaves.
Their flowers are among the most diverse and unusual, although often very small, and specialise in using tiny insects such as gnats or Chalcid wasps for pollination.
To bring some order in this extremely diverse genus, 29 subgenera and 25 sections have been created. Much of this work has been done by Dr. C. Luer. A new analysis, based on DNA testing, has confirmed on the whole this classification of the subtribe Pleurothallidinae, with however Pleurothallis as the main difference. This should not surprise anyone, since this somewhat artificial genus has been the dumping ground for species that did not fit into any other genus. New genetic insight will eventually break up this huge genus and make it more consistent with the principles of monophyletic genera and evolutionary relationships. Several times a splitting up has been attempted, but there were always too many intermediate forms. The subgenus Acianthera is a good candidate for becoming a separate genus, as well as the subgenera Pleurothallis and Specklinia. The subgenus Acuminatae might become the proposed genus Anathallis. Several more changes have been proposed, but it still premature for a final judgment.
Other allied genera include:
Species
This is a long list, with about 1240 species. See List of Pleurothallis species.
A few have common names :
- Pleurothallis angustifolia : Wilson's Bonnet Orchid
- Pleurothallis appendiculata : Hand Bonnet Orchid
- Pleurothallis aristata : Forest Bonnet Orchid
- Pleurothallis domingensis : Guadeloupe Bonnet Orchid
- Pleurothallis immersa : Black Orchid
- Pleurothallis oblongifolia : Ladies' Bonnet Orchid
- Pleurothallis obovata : South American Bonnet Orchid
- Pleurothallis pruinosa : Waxy Bonnet Orchid
- Pleurothallis pubescens : Hairy Bonnet Orchid
- Pleurothallis ruscifolia : Green Bonnet Orchid
- Pleurothallis segoviensis : Trout-fly Orchid
Reference
- Luer, Carlyle; 1986 - Icones Pleurothallidinarum III: Systematics of Pleurothallis (Orchidaceae); Missouri Botanical Garden Press.
- Pridgeon, A., and M. Chase. 2001. A phylogenetic reclassification of Pleurothallidinae (Orchidaceae). Lindleyana 16: 235-271.
External link
- Analysis of the DNA-Based Reclassification of the Pleurothallidinae (http://www.loujost.com/DNAFrameset/DNAanalysisDocument.htm)
- Orchids of the Pleurothallid Alliance (http://www.pleurothallids.com/)
- Photos (http://www.msu.edu/user/zablotn1/pleuros/genera/pleuro/pleuro.htm)