Oncidium, abbreviated as Onc. in the horticultural trade,[1] is a genus that,, contains about 340 species of orchids from the subtribe Oncidiinae of the orchid family Orchidaceae. It is distributed across tropical and subtropical America from Mexico, Central America and the West Indies to northern Argentina, with one species (O. ensatum) extending into Florida.[2] Common names for plants in this genus include dancing-lady orchid and golden shower orchid.
A 2008 molecular phylogenetic study labeled the Oncidium alliance "grossly polyphyletic."[3] In the same year, the American Orchid Society labeled the genus a "dumping ground".[4] A consensus announced in April 2013 resulted in major taxonomic changes to Oncidium, Gomesa, Odontoglossum, Miltonia, and others.[5] Much of this debate and subsequent housekeeping was initiated by significant research for the scientific publication Genera Orchidacearum Volume 5.[6] As a result, much of the information in this article is now deprecated, but still of great value. One significant change is the move of most Brazilian Oncidium with a fused lateral sepal to the genus Gomesa.[4] [3] The Royal Horticultural Society system, the World Checklist of Monocots database[7] and the American Orchid Society have updated their databases to reflect most of these changes.
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 lithophytes (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:
Oncidium species are characterised by the following properties :
The flowers 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 ''Lemboglossum''], 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 accepted by Plants of the World Online :
Selected species not accepted by Plants of the World Online :
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,[8] so that nothogenus names which include these three genera are redundant.
| Nothogenus | Parents | |
|---|---|---|
| × Adacidium | Ada × Oncidium | |
| × Adoncostele | Ada × Oncidium × Rhynchostele | |
| × Aliceara | Brassia × Miltonia × Oncidium | |
| × Arthurara | Brassia × Miltonia × Oncidium × Rhynchostele | |
| × Aspacidopsis | Aspasia × Miltoniopsis × Oncidium | |
| × Aspacidostele | Aspasia × Oncidium × Rhynchostele | |
| × Aspasium | Aspasia × Oncidium | |
| × Brapacidium | Aspasia × Brassia × Oncidium | |
| × Brascidostele | Brassia × Oncidium × Rhynchostele | |
| × Brassidiocentrum | Brassia × Oncidium × Trichocentrum | |
| × Brassidium | Brassia × Oncidium | |
| × Brassidomesa | Brassia × Gomesa × Oncidium | |
| × Brassoncidopsis | Brassia × Miltoniopsis × Oncidium | |
| × Crawshayara | Aspasia × Brassia × Miltonia × Oncidium | |
| × Cuitlacidium | Cuitlauzina × Oncidium | |
| × Cyrtocidistele | Cyrtochilum × Oncidium × Rhynchostele | |
| × Cyrtocidium | Cyrtochilum × Oncidium | |
| × Cyrtoncidopsis | Cyrtochilum × Miltoniopsis × Oncidium | |
| × Dunningara | Aspasia × Miltonia × Oncidium | |
| × Gomiltidium | Gomesa × Miltonia × Oncidium | |
| × Gomonciada | Ada × Gomesa × Oncidium | |
| × Gomoncidochilum | Cyrtochilum × Gomesa × Oncidium | |
| × Howeara | Leochilus × Oncidium × Rodriguezia | |
| × Lockcidium | Lockhartia × Oncidium | |
| × Milenkocidium | Miltonia × Oncidium × Zelenkoa | |
| × Milmilcidium | Miltonia × Miltoniopsis × Oncidium | |
| × Milonzina | Cuitlauzina × Miltonia × Oncidium | |
| × Miltadium | Ada × Miltonia × Oncidium | |
| × Miltoncentrum | Miltonia × Oncidium × Trichocentrum | |
| × Miltoncidostele | Miltonia × Oncidium × Rhynchostele | |
| × Miltonidium | Miltonia × Oncidium | |
| × Oncidesa | Gomesa × Oncidium | |
| × Oncidettia | Comparettia × Oncidium | |
| × Oncidopsis | Miltoniopsis × Oncidium | |
| × Oncidpilia | Oncidium × Trichopilia | |
| × Oncidumnia | Oncidium × Tolumnia | |
| × Oncostele | Oncidium × Rhynchostele | |
| × Oncostelopsis | Miltoniopsis × Oncidium × Rhynchostele | |
| × Otorhynchocidium | Oncidium × Otoglossum × Rhynchostele | |
| × Pettitara | Ada × Brassia × Oncidium | |
| × Psychocidium | Oncidium × Psychopsis | |
| × Reicheara | Aspasia × Miltonia × Miltoniopsis × Oncidium | |
| × Rodricidium | Oncidium × Rodriguezia | |
| × Scelodium | Oncidium × Scelochilus | |
| × Schunkeara | Brassia × Miltonia × Miltoniopsis × Oncidium | |
| × Trichocidium | Oncidium × Trichocentrum | |
| × Warneara | Comparettia × Oncidium × Rodriguezia | |
| × Zelencidiostele | Oncidium × Rhynchostele × Zelenkoa | |
| × Zelencidopsis | Miltoniopsis × Oncidium × Zelenkoa | |
| × Zelenkocidium | Oncidium × Zelenkoa |