The Oncidium Alliance Orchids.

The plants described below belong to a sub-tribe known as the Oncidiinae. They grow naturally in the tropical and sub-tropical Americas and the Caribbean, mainly as epiphytes. There are a confusing number of genera and hundreds of species. Some sections interbreed freely in cultivation and there are a large number of intergeneric names. The taxonomists have recently had a field day with this sub-tribe and many plants we know as odonto- glossums and oncidiums have been reclassified and given new names.

Brassia

The aptly named spider orchids have long, narrow petals and sepals. Native to tropical America, they can be grown under the same conditions as cattleyas, and appreciate lots of light. The flowers dispose themselves neatly along arching or drooping clusters. Grow them for their form; the colors are muted and the fragrance odd, if perceptible at all. They have contributed something of their long-legged look to a number of intergeneric hybrids.

Brassia arcuigera (B. longissima)
The inflorescence can reach 2 1/2 feet, with a half dozen or more yellow or greenish yellow flowers heavily banded with brown. Each flower segment can reach 10 inches in length.
Brassia caudata
This species resembles B. arcuigera, but the flowers are somewhat smaller – to 7 or 8 inches in spread.
Brassia gireoudiana
The flowers are 10 to 12 inches across with extremely narrow, stiff segments.
Brassia verrucosa
The spidery flowers are yellowish to lime green with dark red spots and green warts. Their fragrance is musky.

Cochlioda

These attractive orchids are similar to Odontoglossum in habit and require the same cool growing conditions. They have proved extremely important in bringing bright color into a number of hybrids with Odontoglossum and Miltonia.

Cochlioda noezliana
The 16- to 18-inch inflorescence carries a dozen or more 2-inch, bright reddish orange flowers with a yellow spot on the lip. Summer bloom.
Cochlioda rosea
This species resembles C. noezliana, but its slightly larger flowers vary from deep rose pink to dark red. Blooms in spring and summer.

Comparettia

These are dwarfish plants with leathery leaves and little in the way of pseudo bulbs. They can be grown in small pots, but do better on a slab. Comparettia orchids do not like high light intensities, needing much the same growing environment as Colombian miltoniopsis. They bear up to 20 or so 2 in (5 cm) or smaller showy flowers on a stem, the large lip being a prominent feature. Comparettia coccinea has red flowers; C. falcata has cerise flowers and C. speciosa has striking orange flowers.

Cuitlauzina Pendula

Formerly known as Odontoglossum pendulum (0. citrosmum), this cool grower has 6-inch pseudo bulbs and 12-inch leaves. The arching then drooping inflorescence is 1 1/2 to 3 feet long and is crowded with 3-inch pure white or pink-lipped flowers. These appear from late spring to autumn and have a sweet lemony scent.

Grow this orchid in a hanging basket or pot to accommodate the trailing inflorescence. Keep it dry in winter, misting or watering just enough to keep the pseudo bulbs from shriveling. It is hardy, possibly to 20°F (-7°C).

Lemboglossum

Many of the Mexican and Central American members of Odontoglossum have been reassigned to this genus. (It is a reminder of the evanescence of botanical standing that they may eventually be called Rhynchostele.) Like members of Odontoglossum, they are cool growers, though more warmth tolerant.

Lemboglossum bictoniense (Odontoglossum bictoniense)
Foliage clumps to 16 inches produce stiffly erect flowering stems with a host of 2-inch yellow and brown flowers with white or pink lips. Fall blooming.
Lemboglossum cervantesii
The 6-inch-tall plant produces drooping clusters of two to six 2- to 3-inch white or pale pink flowers. The bases of the petals and sepals are marked by brownish lines that form a series of concentric half-circles. This cool grower has over wintered in the Pacific Coast fog belt with minimal protection.
Lemboglossum rossii (Odontoglossum rossii)
The 8-inch inflorescence bears three to five 2- to 3-inch white, yellow, or pale pink flowers with dark brown spots and stripes. Winter bloom.
Lemboglossum uro-skinneri (Odontoglossum uro-skinneri)
Inflorescences to 2 1/2 feet bear up to twenty 1-inch-wide, green and brown flowers with pink, white-spotted lips.

Miltonia

These are referred to as Brazilian miltonias, a term often used to distinguish them from Miltoniopsis when both were called miltonias. The flowers are more star-shaped and with a less generous lip than their Colombian cousins.

This genus has been extensively used with other members of the oncidium alliance to produce many widely grown intergeneric hybrids. A species still very popular in cultivation is Miltonia spectabilis, with flattened pseudo bulbs and 6 in (15 cm) yellowish-green foliage. The somewhat flattened flower stems bear one or two 3 in (7.5 cm) flowers in summer. Variety moreliana has large, deep-purple flowers and is widely cultivated. Brazilian miltonias have a reputation of being easy to grow. They are more tolerant of less-than-perfect conditions than the Colombian miltoniopsis. They will grow with, and can be treated the same as, cattleyas.

Miltonia regnellii
Brazilian. The 16-inch flower stalk bears three to five 3-inch flowers of creamy white and pink, with purplish markings. Late summer and fall bloom.
Miltonia spectabilis
Brazilian. The flowers are borne singly on 10-inch stalks; they are white, tinged rose toward the base, and have a purplish red lip. The variety M. s. moreliana has larger flowers of dark purple. Autumn bloom.

Miltoniopsis

This is the name now given to the so-called Colombian miltonias, although they are found elsewhere. They are still treated as the genus Miltonia in naming intergeneric hybrids with other genera, and are often referred to as “pansy orchids”, due to the general appearance of the flowers. One to several flowers open on a stem in colors ranging from white or yellow to deep purple, often with a central pattern of a different color, called a mask. The plants have oval, compressed pseudo bulbs and 8 in (20 cm), fragile looking, gray-green leaves. Hybrids seem to be grown most often these days but occasionally seen are two of the important ancestral species, Miltoniopsis vexillaria and Miltoniopsis roezlii.

Miltoniopsis are high-elevation plants from wet cloud forests. Light intensity, temperatures and potting media are the same as for Odontoglossum. Do not over-pot, water before the medium has quite dried out in summer but let it dry out (but not for long) in winter.

Having said this, it is noticeable that growers with the most superbly grown and flowered plants usually keep their nightly minimum temperatures between 54°F (12°C) and 60°F (15°C). These plants are ideal for growing on window sills and in the company of Phalaenopsis. The flowering season is spring and summer.

Miltoniopsis phalaenopsis
Colombian. Clumps of 8- to 9-inch gray green leaves produce sprays of three to five flowers 2 1/2 to 3 inches wide; these are pure white with purplish red or purple markings on the lip. This is an important parent of the pansy orchids. Late summer and fall bloom.
Miltoniopsis roezlii
Colombian. Pale green foliage masses produce two to four 4-inch white flowers with a deep purple blotch. An important parent of the pansy orchids. Winter and spring bloom.
Miltoniopsis vexillaria
Colombian. Pale green foliage clumps have leaves to 10 inches long. Sprays hold four to six 4-inch flowers of bright rose, marked at the center with white, yellow, and red. Each new growth may produce several sprays. This is a principal parent of many pansy orchids. Spring and summer bloom.

Odontoglossum

This once-large genus has been reduced by attrition, all of its Central American and Mexican species having been spirited off into other genera. To avoid confusion those refugees are listed here, but with a cross-reference to their new names. Most of the remaining “true” odontoglossums are cool-growing plants from the high, cool, misty mountains of South America. Many of the hybrids with other genera are more tolerant of intermediate temperatures.

Odontoglossum crispum
Considered by many to be the most beautiful orchid of all, it is also one of the most difficult to grow – unless you live in a cool marine climate. The California fog belt does well with it, as does the Pacific Northwest. Elsewhere, high daytime temperatures will enfeeble and destroy it, unless air-conditioning is available. The 2 1/2- to 3- inch flowers are white or pale rose with fringed and crimped edges and a scattering of reddish brown dots. The 20-inch-long, drooping inflorescences carry 6 to 24 flowers; they usually appear in spring and summer, but may appear at any time.
Odontoglossum harryanum
The erect inflorescence is 20 to 36 inches tall and bears as many as 12 flowers. Flowers are 3 inches wide, with wavy segments of rich reddish brown marked with yellow. The large lip is reddish brown and white. Summer bloom.
Odontoglossum luteopurpureum
Like O. harryanum, this species carries up to a dozen 3- to 4-inch flowers of chestnut brown marked with yellow. The lip is yellowish white marked with brown. Spring bloom.

Oncidium

The number of species in Oncidium ranges in estimate from 300 to as many as 600. They grow from Mexico and the Caribbean islands to the southern borders of Brazil; a few stragglers have been found in southern Florida. Some grow in the sweltering lowlands; others favor the high, cool, misty mountains. Most will thrive in intermediate temperatures given bright light, ample water during growth and bloom, no complete drying-out, and good air circulation.

Grow oncidiums in pots or baskets filled with bark or perlite and bark. Some of the smaller ones are attractive mounted on pieces of wood, bark, or tree fern. Those with drooping sprays should be grown in hanging baskets. Some have tall, branching inflorescences that will require staking.

In most species slender, branching sprays of flowers come in shades of yellow and red or reddish brown, but a few are white or pink. The flowers of most have flaring petals, often expanded toward the tips, and a full, ruffled lip; to some they suggest dancing dolls or ballerinas. The flowers last well, both on the plant and when cut. Florists call them spray orchids. Only a representative few can be mentioned here.

Oncidium ampliatum
Flat, ridged, turtle-shaped pseudo bulbs produce leaves to 16 inches long. The branching flower clusters can reach 3 feet and hold hundreds of inch-wide yellow flowers spotted with reddish brown. Spring bloom.
Oncidium carthagenense
A “mule ear” oncidium, in which the fleshy leaves serve the function of pseudo bulbs. These nearly erect leaves are up to 20 inches long, and the branching 5- to 6-foot flower stem produces a host of round, ruffled white flowers heavily marked with purplish brown. Summer bloom.
Oncidium cheirophorum
Inch-wide pseudobulbs carry two 4- to 10-incn leaves. The 8-inch flower stem holds many fragrant, firm-textured, bright yellow flowers 1/2 inch wide. The plant’s small size makes it a natural for growing under artificial light. Blooms two or three times a year. This is a fine orchid for beginners.
Oncidium crispum
A cool-grower from Brazil that will tolerate lower temperatures than most other oncidiums. It has long rhizomes and long, wandering roots. Difficult, but not impossible to keep in a pot, it does well on a large slab. The inflorescence is branched and can carry many handsome 3 in (8 cm) flowers of a glossy chestnut color. Not to be confused with Odontoglossum crispum. Similar species of smaller plants include Oncidium forbesii and Oncidium sarcodes.
Oncidium guianense (0. desertorum)
This is one of the equitant oncidiums-those that lack pseudo bulbs and display their leaves in fans, somewhat like a miniature iris. The leaf fan is just 1 1/2 inches tall, and the 6-inch flower stem bears several 1-inch, bright yellow flowers. This is a good plant to mount on a branch or on a piece of bark. Fall blooming.
Oncidium lanceanum
Another “mule ear,” this striking plant has stiff, erect, brown-mottled leaves 20 inches long and 4 inches wide. The foot-tall flower stem produces a -few to several 2- to 2 1/2-inch yellow flowers with heavy reddish brown spotting and a purplish rose lip. Summer blooming.
Oncidium luridum
This is a large plant with thick, rigid leaves. The branched inflorescence can be well over 39 in (1 m) long, carrying many 1 1/4 in (3 cm) yellow and reddish-brown flowers. Oncidium cavendishianum, Oncidium lanceanum and Oncidium carthagenense are similar plants and are referred to as “mule ear orchids”. They prefer higher night temperatures and higher light levels than other oncidiums. Water with caution when not in active growth. These orchids are spring- and summer- flowering.
Oncidium ornithorhynchum
MAIDENHAIR ORCHID. This small species has foot-long leaves and an 18- to 20-inch arching inflorescence crowded with fragrant pink to rosy lilac inch-wide flowers. It appreciates somewhat cool conditions. Summer bloom.
Oncidium sharry baby
This summer and fall-blooming hybrid produces tall, branching spikes with dozens of 1-inch pinkish or reddish flowers exuding a powerful scent of chocolate (according to some) or vanilla. ‘Sweet Fragrance’ is a choice selection.
Oncidium sphacelatum
Large pseudo bulbs produce narrow leaves up to 3 feet long. Branched inflorescences are 3 to 5 feet tall, erect, and bear scores of inch-wide yellow flowers spotted with reddish brown. Winter to spring bloom.
Oncidium varicosum
The sepals and petals are relatively small, the dominant feature being the 1 1/2 in (4 cm) or wider pure yellow lip. Long, branched stems can carry as many as 100 flowers, or even more on a strong plant. A gentle breeze will move the flowers in a fanciful floral ballet, hence the common name for this and similar species of “dancing doll orchid”. Mostly seen in cultivation is the superior variety o. varicosum var rogersii, which flowers in fall through to spring. It is often used to make hybrids where its shape and color is dominant even into the second generation. It is also very tolerant of temperature variations.

Osmoglossum

Once included in Odontoglossum, these plants differ in having small, white, very fragrant flowers. Less dependent on coolness than Odontoglossum, they thrive at intermediate temperatures.

Osmoglossum convallarioides (Odontoglossum convallariodes)
A medium-size plant with an inflorescence up to 16 inches long, carrying a few 1-inch white flowers. Spring blooming.
Osmoglossum pulchellum (Odontoylossum pulchellum)
LILY-OF-THE-VALLEY ORCHID. The 20-inch erect or nodding inflorescence bears three to ten creamy flowers 1 to 2 inches across. Their fragrance recalls that of lily-of-the-valley. Spring blooming.

Psychopsis

The butterfly orchids were formerly included in the Oncidium genus; they differ from it in producing a succession of single flowers from the top of the inflorescence down. The flowers are large and oddly formed: the dorsal sepal and petals (the upper half of the flower) are extremely narrow, resembling antennae. The lower sepals and lip, in contrast, are broad and strongly marked.

Grow them on a raft or in a pot filled with coarse bark. They prefer intermediate temperatures. Do not remove the flower stalk after the flower fades; it may continue to produce flowers for several years. Bloom is sporadic throughout the year.

Psychopsis krameriana (Oncidium kramerianum)
The flowering stem is 2 to 3 feet tall and carries one single 4- to 5-inch flower at a time. The flower is reddish brown strongly marked with yellow; its lip is yellow with a reddish brown border.
Psychopsis papilio (Oncidum papilio)
This species strongly resembles P. krameriana, but its colors are strongly banded instead of being marked at random.

Psygmorchis Pusilla

This tiny orchid has no pseudo bulbs; instead, its leaves grow in a fan like a miniature iris. The entire plant is just 3 inches tall. Each flowering stem produces one to six 1-inch-wide flowers in succession. These are yellow, with faint brown markings. Grow this one on a bark raft or a piece of tree fern. It needs a humid atmosphere, but the roots should dry out between watering.

Rodriguezia

These small, easily grown plants come from the forests of Central America and northern South America. Grow them like cattleyas, except that they need no rest period. They flourish either on rafts or potted in fine bark. Give them ample water throughout the year. Bloom may occur at any time of year.

Rodriguezia batemannii
The 10-inch inflorescence, erect or drooping, carries as many as ten fragrant 2 1/2-inch flowers, white marked with yellow or lilac.
Rodriguezia lanceolata (R. secunda)
The 4- to 16-inch inflorescence bears many inch-wide rose red flowers with a white mark at the base of the lip.
Rodriguezia venusta
White, strongly fragrant flowers 1 1/2 inches wide are borne on a 4- to 8-inch arching inflorescence.

Rossioglossum Grande

TIGER ORCHID. This large, very showy orchid thrives in cool to intermediate conditions. The 6- to 12-inch inflorescence carries two to eight 6-inch, glossy, heavy-textured flowers of yellow barred in a deep reddish brown. The growing medium should be fine bark containing some leaf mold. Water the plants heavily when in growth; then withhold water, giving them only enough to prevent the shriveling of the pseudo bulbs. Re-pot the plants and resume watering when new growth begins. Bloom occurs in winter.

Trichocentrum

These small growers have relatively large flowers. Their pseudo bulbs are small or absent, their leaves fleshy or leathery, their horizontal inflorescences short with few flowers. Grow them on rafts or in pots. They thrive under cattleya conditions.

Trichocentrum albococcineum
The 3-inch inflorescence bears one to three 2-inch flowers of yellow brown or yellow green with a white and purple lip. Late summer to autumn bloom.
Trichocentrum pulchrum
Similar to T. albococcineum, but with white flowers spotted in purplish red.

Trichopilia

These compact, intermediate-temperature orchids have relatively large cattleya-shaped flowers on short, few-flowered stems, several of which may spring from a single pseudo bulb. Give plants Oncidium conditions: plenty of water during the growing season followed by a 2- to 3-week rest period.

Trichopilia suavis
The short, arching or drooping inflorescence bears from one to four 4-inch flowers. The wavy sepals and petals are creamy white, sometimes spotted with red. The large, wavy-edged lip is white, heavily spotted with rosy red. These flowers are strongly fragrant. Spring bloom.
Trichopilia tortilis
The narrow, twisted petals and sepals are brownish purple or rosy lavender. The large, nearly round lip is white, spotted with red and brown. Spring or fall bloom.

Intergeneric Hybrids

Hybridizers have had a field day crossing the many genera in the Oncidium alliance. Most hybrids represent a distinct improvement over their parents, in either appearance or ease of culture. The latter is the result of hybrid vigor (heterosis): an increase in size or tolerance of varying conditions that results from the combined genes of the two parents. The number of these hybrids is so great that only a cursory mention of them is possible here. Odontoglossum, Oncidium, and Miltonia have been the principal genera involved, but Cochlioda and other genera have been used as well.

The genus Oncidium contributes both vigor and a free-blooming habit to many of these crosses, along with a propensity to produce yellow and brown flowers with prominent lips. Miltonia and Odontoglossum contribute large flower size. (The broad petals and sepals of Odontoglossum tend to compensate for the small flower parts of Oncidium. )

The color range draws on Oncidium and Odontoglossum for russet and yellow tones. From Miltonia comes a velvety finish and broad, rounded contours. Cochlioda, Rodriguezia, and Trichocentrum contribute bright color and moderate plant size. Crosses involving Brassia show a marked increase in the length of the sepals and petals. Following are a few of the many names you are likely to encounter.

*Aliceara
Crosses among Brassia, Miltonia, and Oncidium, these may be either pink or yellow and brown on long sprays.
*Burrageara
The ancestry of these hybrids includes Miltonia, Cochlioda, Odontoglossum, and Oncidium. Plants produce tall, many-flowered spikes with nicely spaced flowers in a variety of colors. They prefer cool to intermediate conditions.
*Maclellanara
These hybrids involve Brassia, Odontoglossum, and Oncidium. The grex Pagan Lovesong has erect spikes to 3 feet bearing many large, star-shaped yellow flowers spotted with brown. The lip is white with brown markings. It prefers cool to intermediate temperatures.
*Odontioda
These crosses between Odontoglossum and Cochlioda yield large, round flowers of Odontoglossum crispum form and bright red or brownish red markings profusely scattered over a white or yellow ground. Though cool growers, they tolerate more warmth than does Odontoglossum.
*Odontocidium
Crosses between Odontoglossum and Oncidium, these have branched or unbranched inflorescences with yellow, orange, red, or spotted flowers. They are cool to intermediate growers.
*Odontonia
Hybrids between Odontoglossum and Miltonia, these are generally cool growing. Flowers on tall, usually unbranched, stalks are white, yellow, or red, often heavily marked with a contrasting color.
*Vuylstekeara
The offspring of x Odontioda crossed with Miltonia, these have branched or unbranched inflorescences carrying pink, red, or red and white flowers.
*Wilsonara
These hybrids number Cochlioda, Odontoglossum, and Oncidium in their ancestry. Frilly flowers heavily marked in brilliant colors on tall spikes have an Oncidium form. These are cool to intermediate growers.
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