Oncidium, abbreviated as Onc. in the horticultural trade,[ Flora of North America, v 26 p 648, Oncidium ensatum ] Common names for plants in this genus include dancing-lady orchid
A molecular phylogenetic study published in 2009 labeled the Oncidium alliance "grossly Polyphyly."[Lindleyana : The scientific journal of the American Orchid Society. December 2008 Pg 20] A consensus announced in April 2013 resulted in major taxonomic changes to Oncidium, Gomesa, Odontoglossum, Miltonia, and others.[ The Royal Horticultural Society system, the World Checklist of Monocots database]
Description
This genus was first described by Olof Swartz in 1800 with the orchid Oncidium altissimum, which has become the type species. Its name is derived from the Greek word ὀγκος, onkos, meaning "swelling". This refers to the callus at the lower lip.
Most species in the genus are epiphytes (growing on other plants), although some are (growing on rocks) or terrestrials (growing in soil). They are widespread from northern Mexico, the Caribbean, and some parts of South Florida to South America. They usually occur in seasonally dry areas.
They can be divided into three categories, according to their growth pattern:
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Some have green and long with small flowers and a dominant lip. They are mostly golden yellow with or without reddish-brown barring, but some are brown or yellowish-brown. Other Oncidium species have white and pink blooms, while some even have startling, deep red colors in their flowers.
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Another group has extremely small pseudobulbs and stiff, erect, solitary leaf. These cylindrical leaves act as a water reserve. They have long racemes with yellow flowers that seem to fan out at the top. Sizes of these orchids can vary from miniature plants of a couple of centimetres to giants with 30 cm-long leaves and racemes of more than one metre long. These species, known as the Mule-Ears, are now classed as Psychopsis.
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Formerly there was a third group, called the Variegata or equitant oncidiums. They have no pseudobulbs, giving fan-shaped shoots of less than 15 cm, with triangular section leaves. These oval, broad and spongy leaves act as storage organs. Their flowers are most complicated with exquisite colors. The sepals are somewhat fleshy. The petals and the lip are membranaceous. These orchids are now classified as Tolumnia. Cyrtochilum is another genus that many Oncidium species have been reclassified into; Cyrtochilum species have extremely long, winding inflorescences that can sometimes reach 20' or more, curled petals that result in three-pointed blooms, and rambling growth habits in which each new pseudobulb appears on top of the old one.
Oncidium species are characterised by the following properties :
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presence of column wings,
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presence of a complicated callus on the lip (this can be used to separate the taxa),
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with one to three leaves,
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several basal at the base of the pseudobulbs.
The come in shades of yellow, red, white and pink. The petals are often ruffled on the edges, as is the lip. The lip is enormous, partially blocking the small petals and sepals.
Some Oncidium orchids are very tall: Oncidium altissimum and Oncidium baueri can grow to a height of 5 m.
They are known as 'spray orchids' among some florists. They are very varied and are easily hybridised with other closely related genera forming the Oncidium alliance ( Miltonia, Cuitlauzina, Miltoniopsis, Leochilus, Comparettia, Cyrtochilum, Tolumnia, Rhynchostele formerly, Psychopsis, etc.). Some of the best Oncidium alliance hybrids originate from Oncidium tigrinum and Oncidium incurvum when crossed with species formerly placed in Odontoglossum, although hybridization possibilities of this group of orchids are endless, and there are literally hundreds of thousands of hybrids in the Oncidium alliance.
Selected species
Selected species accepted by Plants of the World Online :
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Oncidium altissimum : "Heinrich Wydler's dancing-lady orchid" (Jamaica)
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Oncidium baueri (Trop. America)
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Oncidium cheirophorum (Mexico - Chiapas to Colombia)
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Oncidium citrinum (Trinidad to Venezuela)
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Oncidium deltoideum (N. Peru)
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Oncidium dichromaticum (Costa Rica to Colombia)
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Oncidium ensatum : (S. Mexico, Belize, Cuba, Florida, Bahamas, NW. Venezuela)
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Oncidium fuscatum (Ecuador to Peru)
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Oncidium geertianum (C. & SW. Mexico)
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Oncidium graminifolium (Mexico to C. America)
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Oncidium harryanum (Colombia)
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Oncidium hastatum (Mexico)
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Oncidium hastilabium (W. South America)
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Oncidium incurvum (Mexico - Veracruz to Chiapas)
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Oncidium lentiginosum (Colombia to N. Venezuela)
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Oncidium leucochilum (SE. Mexico to Guatemala)
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Oncidium lineoligerum (N. Peru)
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Oncidium maculatum (Mexico to C. America)
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Oncidium naevium (Colombia to Guyana)
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Oncidium noezlianum (N. Peru to Bolivia)
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Oncidium ornithorhynchum (Mexico to C. America)
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Oncidium reflexum (SW. Mexico)
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Oncidium sphacelatum (Mexico to C. America, SE. Venezuela)
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Oncidium strictum (Cogn.) M.W.Chase & N.H.Williams (Ecuador, Peru)
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Oncidium wentworthianum (Mexico – Chiapas to El Salvador)
Former species
Selected species not accepted by Plants of the World Online :
File:Oncidium sphacelatum 3.jpg| Oncidium sphacelatum
File:Oncidium Sharry Baby - smells like chocolate.jpg| Oncidium Sharry Baby smells like chocolate.
Nothogenera
Many hybrids have been created artificially involving species of Oncidium, often with species of other genera. Named hybrid genera (nothogenera) are listed in the table below, together with their parent genera. , Cochlioda and Odontoglossum are included within Oncidium,[ and Baptistonia within Gomesa,]+ Nothogenera involving Oncidium |
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| Ada × Oncidium |
| Ada × Oncidium × Rhynchostele |
| Brassia × Miltonia × Oncidium |
| Brassia × Miltonia × Oncidium × Rhynchostele |
| Aspasia × Miltoniopsis × Oncidium |
| Aspasia × Oncidium × Rhynchostele |
| Aspasia × Oncidium |
| Aspasia × Brassia × Oncidium |
| Brassia × Oncidium × Rhynchostele |
| Brassia × Oncidium × Trichocentrum |
| Brassia × Oncidium |
| Brassia × Gomesa × Oncidium |
| Brassia × Miltoniopsis × Oncidium |
| Aspasia × Brassia × Miltonia × Oncidium |
| Cuitlauzina × Oncidium |
| Cyrtochilum × Oncidium × Rhynchostele |
| Cyrtochilum × Oncidium |
| Cyrtochilum × Miltoniopsis × Oncidium |
| Aspasia × Miltonia × Oncidium |
| Gomesa × Miltonia × Oncidium |
| Ada × Gomesa × Oncidium |
| Cyrtochilum × Gomesa × Oncidium |
| Leochilus × Oncidium × Rodriguezia |
| Lockhartia × Oncidium |
| Miltonia × Oncidium × Zelenkoa |
| Miltonia × Miltoniopsis × Oncidium |
| Cuitlauzina × Miltonia × Oncidium |
| Ada × Miltonia × Oncidium |
| Miltonia × Oncidium × Trichocentrum |
| Miltonia × Oncidium × Rhynchostele |
| Miltonia × Oncidium |
| Gomesa × Oncidium |
| Comparettia × Oncidium |
| Miltoniopsis × Oncidium |
| Oncidium × Trichopilia |
| Oncidium × Tolumnia |
| Oncidium × Rhynchostele |
| Miltoniopsis × Oncidium × Rhynchostele |
| Oncidium × Otoglossum × Rhynchostele |
| Ada × Brassia × Oncidium |
| Oncidium × Psychopsis |
| Aspasia × Miltonia × Miltoniopsis × Oncidium |
| Oncidium × Rodriguezia |
| Oncidium × Scelochilus |
| Brassia × Miltonia × Miltoniopsis × Oncidium |
| Oncidium × Trichocentrum |
| Comparettia × Oncidium × Rodriguezia |
| Oncidium × Rhynchostele × Zelenkoa |
| Miltoniopsis × Oncidium × Zelenkoa |
| Oncidium × Zelenkoa |
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Harry Zelenko :The Pictorial Encyclopaedia of Oncidium (1997)
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Koniger, W. 2003. New species of the genera Masdevallia, Oncidium and Sigmatostalix. Arcula no. 12: 298–311.
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