Oncidium

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Plant Characteristics
Cultivation
Scientific Names

Oncidium >


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Read about Oncidium in the Standard Cyclopedia of Horticulture 

Oncidium (Greek, a tubercle; alluding to the crest on the labellum). Orchidaceae. Epiphytal orchids for greenhouse growing.

Pseudobulbs usually present, wanting in a few species, 1-2-lvd., with sheathing Lvs. at the base: Lvs. plane, terete or triangular: petals like the dorsal sepal but often much larger; lateral sepals either free or partially united; labellum variable, but never with its base parallel to the column (Odontoglossum), spreading nearly at right angles to the column; column short, winged.—A broad genus with over 300 species distributed in Mex., Cent, and Trop. Amer., and in the W. Indies. In range of altitude the genus extends from the hot coast regions to elevations of 12,000 ft. in the Andes. The fls. of this genus show a remarkable diversity of form. In O. varicosum, O. tigrinum and related species, the labellum is greatly developed, forming the most conspicuous part of the fl., while in O. serratum and O. macranthum it is inconspicuous. The sepals and petals vary in size in relation to each other and to the rest of the fl. A remarkable example is O. Papilio, in which the petals and dorsal sepal have been transformed into linear-erect segms., recalling, on a large scale, the antennae of some insect. The general habit of the plants is no less variable than the fls. They range in size from small erect forms, scarcely 6 in. in height (O. pumilum), to those resembling 0. altissimum, with immense climbing panicles 9-12 ft. high and covered with numerous medium-sized fls. The prevailing color of the fls. is yellow, spotted and barred with brown. White or rose-colored fls. occur in a few rare examples (O. incurvum, O. ornithorhynchum).

As a class, oncidiums are short-lived under cultivation. Few growers succeed in maintaining them in good condition for any great length of time. The stock is constantly renewed from the tropics.

Cultivation of oncidiums.

The genus Oncidium embraces a great number of species which are found growing under such peculiar and varied conditions in their native homes that imitation of the same is usually impracticable and often quite impossible. A fair degree of success, however, may be obtained by careful observation and distribution of the exceptionally difficult species among the several orchid departments. The Sarcoptera section, which embraces such species as O. Cavendishianum, O. Lanceanum, O. luridum, 0. pulvinatum and others of similar structure, and the O. Papilio section, with O. ampliatum, may be successfully grown in a bright warm portion of the cattleya department in small baskets suspended from the roof, using for a compost a mixture of clean chopped peat and sphagnum moss, freely interspersed with lumps of broken charcoal. O. cucullatum, O. incurvum, O. macranthum, O. ornithorhynchum, O. Phalaenopsis, O. varicosum, with a few others of like nature, do well under treatment similar to that given for odontoglossums, which see.

When a good collection of species is cultivated, a large number, including many of the above, can be readily grown in one house if it be especially adapted to them. Such a house should be a span-roof structure of east and west exposure, at an angle of about 40°, which will admit the longest possible light. The early morning and late afternoon sun striking the glass at right angles produces and prolongs the natural sun heat for a greater part of the day, while at midday, when the outside temperature is highest, the sun's rays strike the glass obliquely, giving less heat, with little danger of the plants becoming sunburned from lenses in the glass. Oncidiums require more sun and air than most orchids.

The benches may be of either wood or stone, and should be covered an inch or two in depth with sand, ashes or gravel. The benches and paths should be wet down once or twice daily to insure a moist atmosphere. Ventilators should be arranged on both sides of the roof: air may then be freely admitted without causing direct drafts on the plants by using the ventilators on the sheltered side. In winter the temperature should range from 50° to 55° F. at night and 60° to 65° by day, or a few degrees more with sun heat and ventilation. In summer it must be kept as low as outside conditions will permit. From March until October, shading must be applied to the glass sufficiently heavy to keep down the temperature without excluding indirect solar influence. A good shading is made of turpentine and white lead; it stands well and is easily removed. It can be applied rapidly with a whitewash brush on a long pole, and removed with a hard brush in the fall.

Oncidiums may be grown in either pots or baskets, but as many species are of rambling habit, the latter are preferable. The tiny species, such as O. Limminghii, do best on blocks with little compost beneath them. Clean chopped peat fiber and live sphagnum moss, equal parts, make the best general growing material, and this should be liberally interspersed with broken pieces of charcoal. The plants in all cases must be securely fastened, and the compost must be pressed in moderately firm, but should be used sparingly. Overhead syringing should be given frequently, about once or twice a day in bright weather, but care must be taken not to keep the compost too wet, for the roots are liable to decay: it is advisable to let them dry out occasionally.

Stock is increased by division or notching the rhizome between the pseudobulbs just before the growing season, allowing about three or four pseudobulbs to each piece and separating the parts after the first growth is matured.


The above text is from the Standard Cyclopedia of Horticulture. It may be out of date, but still contains valuable and interesting information which can be incorporated into the remainder of the article. Click on "Collapse" in the header to hide this text.



Oncidium
Oncidium incurvum
Oncidium incurvum
Plant Info
Scientific classification
Kingdom: Plantae
Division: Magnoliophyta
Class: Liliopsida
Order: Asparagales
Family: Orchidaceae
Subfamily: Epidendroideae
Tribe: Maxillarieae
Subtribe: Oncidiinae
Genus: Oncidium
Sw.

Species
See text.

Oncidium is a genus that contains about 330 species of orchids from the subfamily Epidendroideae of the orchid family (Orchidaceae). This is a complex, difficult genus, with many species being reclassified. Calls are made for splitting this genus into multiple genera.

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 "onkos", meaning "swelling". This refers to the callus at the lower lip.

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.

They 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, 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.
  • 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 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 Trichocentrum.
  • 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.

Oncidium species are characterised by the following properties :

  • presence of column wings
  • presence of a complicated callus on the lip (this can be used to separate the taxa).
  • pseudobulbs with one to three leaves.
  • several basal bracts at the base of the pseudobulbs.

The flowers of the Oncidium genus 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 long : Oncidum altissimum and Oncidium baueri can grow to a height of 5 m, while Oncidum sarcodes can reach 3 m.

They are known as 'spray orchids' among some florists. They are very varied and are easily hybridised with Odontoglossum. Together with other closely related genera (Cochlioda, Miltonia, Cuitlauzina, Miltoniopsis, Osmoglossum, Leochilus, Comparettia, Cyrtochilum, Odontoglossum, Tolumnia, Rhynchostele [formerly Lemboglossum], Psychopsis, etc.) they form the Oncidium alliance. Some of the best Oncidium alliance hybrids originate from Oncidium tigrinum and Oncidium incurvum, when crossed with Odontoglossums, although hybridization possibilities of this group of orchids are literally endless, and there are literally hundreds of thousands of excellent hybrids in the Oncidium alliance.


Oncidium brunleesianum
Oncidium incurvum - another view
Florida Orchid (Oncidium floridanum)

Species

Wydler's Dancing-lady Orchid (Oncidium altissimum)
File:Oncidium-croesus.jpg
Oncidium croesus
File:Oncidium-flexuosum.jpg
Oncidium flexuosum
File:Oncidium-forbesii.jpg
Oncidium forbesii
File:Oncidium-harrisonianum.jpg
Oncidium harrisonianum
Oncidium longipes
Oncidium macronix
Oncidium pulvinatum
Oncidium sphegiferum


References

Template:Commonscat

  • Harry Zelenko :The Pictorial Encyclopaedia of Oncidium (1997)
  • Koniger, W. 2003. New species of the genera Masdevallia, Oncidium and Sigmatostalix. Arcula no. 12: 298-311.

External link

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