Oncidium pulvinatum © Larsen Twins Orchids

Oncidium pulvinatum

Oncidium ochmatocilum © Conrad Munro

Oncidium ochmatocilum

Pronunciation: on–CEE–dee–um

Scientific Classification

  • Family: Orchidaceae
  • Subfamily: Epidendroideae
  • Tribe: Cymbidieae
  • Subtribe: Oncidiinae
  • Genus: Oncidium, Swartz 1800

General Characteristics

  • epiphytes, although some are lithophytes or terrestrials
  • presence of column wings
  • presence of a complicated callus on the lip
  • pseudobulbs with one to three leaves
  • several basal bracts at the base of the pseudobulbs

Oncidium, abbreviated as Onc in horticultural trade, is a genus that contains about 330 species. This is a complex, difficult genus, with many species being reclassified. Calls are made for splitting this genus into multiple genera.

Most species in the Oncidium genus are epiphytes, although some are lithophytes or terrestrials. They are widespread from northern Mexico, the Caribbean, some parts of South Florida to South-America. They usually occur in seasonally dry areas.

Oncidium can be divided in three categories, according to their growth pattern:

  • Some have green pseudobulbs, and long racemes with small flowers, and a dominant lip. They are mostly golden yellow with or without reddish-brown barring, however, 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.
  • Another group has extremely small pseudobulbs and stiff, erect, solitary leaves. 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 centimeters to giants with 30 cm-long leaves and racemes of more than one meter long. These species are now classed as Psychopsis.
  • 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 recently 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.


  • Temperature: It is impossible to assign a temperature range (other than cool to warm). The grower has to obtain the in situ conditions.
  • Light: These plants grow in shaded to bright, indirect light.
  • Water &Humidity: Weekly watering during the warmer part of the year, reduced watering during the cooler part of the year. Humidity ranges from low to high depending on the in situ conditions.
  • Fertilizer: ¼ strength balance fertilizer for four to five waterings, then one watering without fertilizer.
  • Potting: Fine to coarse medium; provide good aeration.

Selected Species

Browse to Wikipedia to view the entire list of 330 species.


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