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.
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.
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.
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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.
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.
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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).
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.
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.
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
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.
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.
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
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
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-
- 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
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.
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.
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 waterings.
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.
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. Repot the plants
and resume watering when new growth begins. Bloom occurs in winter.
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.
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.
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.
- x Aliceara
- Crosses among Brassia, Miltonia, and Oncidium, these may be either pink or yellow and brown on
- x 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.
- x 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.
- x 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.
- x 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.
- x 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.
- x Vuylstekeara
- The offspring of x Odontioda crossed with Miltonia, these have branched or unbranched
inflorescences carrying pink, red, or red and white flowers.
- x 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.