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Catasetum expansum


Common Name The Expansive Catasetum

Flower Size 3" [7.5 cm]


A large sized, showy, hot to cool growing epiphytic Catasetum from northeastern Ecuador in dry forest at elevations of 20 to 1500 meters with spindle shaped pseudubulbs carrying several deciduous, plicate, lanceolate leaves that can bloom from May until December on a basal, 12" [30 cm] long, several [6] flowered arching raceme arising on a newly forming pseudobulb carying either male or female flowers.

The flowers can be found in many colors including yellow, green, white and sometimes with maroon spots.

Synonyms Catasetum expansum var sodiroi [Schlechter] Mansf.; Catachaetum recurvatum Link 1844; Catasetum cliftonii R.H. Torr. 1911; Catasetum platyglossum Schltr. 1916; Catasetum recurvatum Link 1844; Catasetum sodiroi Schltr. 1921


Sourec: http://www.orchidspecies.com/catasetumexpansum.htm

Photos by © Danny Lentz plant grown by the Atlanta Botanical Garden


 Photos by © Danny Lentz plant grown by the Atlanta Botanical Garden






Description of the Catasetum expansum



A member of subgenus Catasetum section Catasetum. This species is native to low land regions of Ecuador. Expect pseudobulbs to grow 6” – 10” and to be topped by 3-5 arching 10” – 12” long papery textured leaves. With leaves plants will be 18” – 24” tall.  Plants are decidedly deciduous late fall through early spring. Each growth can produce 1-4 inflorescences. Inflorescences are 8” – 14” long and can carry 4-8 flowers each. Individual flowers are 2¾” – 3½” across.


Plants will grow well with Cattleya but will do MUCH better with stronger light. Plants are distinctly deciduous and REQUIRE a dry bright rest period. While in active growth plants enjoy copious warmth and moisture. Permit the plants to dry slightly between watering. When growths mature in late summer slow watering.  The leaves will begin to yellow and will eventually fall. Only water enough to keep the pseudobulbs from shriveling. When the leaves have fallen and the leaf sheathes are dry it is a good practice to gently pull the brown or silvery sheaths off the pseudobulbs. This permits the pseudobulbs to continue photosynthesis and also removes any hiding places that insects may hide.  In spring begin watering normally ONLY when growths are 1” – 4” tall and have roots 2” – 3” long.


All Catasetum (as well as Cycnoches) are paradioecious. This means they produce male or female flowers and can alternate sexes from year to year depending on the strength of the plant. This is a similar situation to the genus Arisaema (Jack-in-the-Pulpit) in the family Araceae. In Catasetum the “prettier” flowers tend to be the males and they are produced in greater number.  Female flowers tend to be smaller with a nondescript pouched labellum and are usually produced 2-4 on much shorter inflorescences.

Source:  https://marlowsorchids.com/inc/sdetail/7723/15244



Catasetum expansum is endemic to western Ecuador, west of the Cerros de Colonche and in the Mira River valley. It grows in dry forest, from near sea level to almost 700 meters.


Catasetum expansum also called as The Expansive Catasetum, Catasetum expansum var sodiroi, Catachaetum recurvatum, Catasetum cliftonii, Catasetum platyglossum, Catasetum recurvatum, Catasetum sodiroi, is a species of the genus Catasetum. This species was described by Heinrich Gustav Reichenbach in 1878.


Catasetum expansum is endemic to western Ecuador, west of the Cerros de Colonche and in the Mira River valley. It grows in dry forest, from near sea level to almost 700 meters.


It is a large sized, showy, hot to cool growing epiphytic with spindle shaped, to 21 cm long and 3.2 cm wide pseudobulbs carrying several deciduous, plicate, lanceolate, to 48 cm long and 7.5 cm wide leaves.


The Expansive Catasetum bloom from May until December on a basal, 30 cm long, 6 flowered arching raceme arising on a newly forming pseudobulb carrying either male or female flowers. The flowers can be found in many colors including yellow, green, white and sometimes with maroon spots. The described flowers are with coloration of sepals and petals pale green, with only a few wine-colored spots on the lateral sepals; lip somewhat darker green; triangular callus in front of the lip orifice covered with "dried blood" color extending all around the orifice; column very light green; antennae white. Female flowers typical for the genus, smaller than the males with coloration green.


Lip form and flower color highly variable, but the species generally can be identified reliably by its broad, flattened lip with large, fleshy callus next to the cavity at the base. Its similarity to Catasetum pileatum, although their habitats are far apart.



Care and Culture

Cultural information should only be used as a guide, and should be to be adapted to suit you. Your physical location; where you grow your plants, how much time you have to devote to their care, and many other factors, will need to be taken into account. Only then can you decide on the cultural methods that best suit you and your plants.



Catasetum expansum are sun-loving plant and needs a light level of 30000-60000 lux. Unless the strong air movement found in the natural habitat can be duplicated, however, the grower should provide some shade (40-60 % shade). This species can be grown under lights if sufficient light intensity can be provided, and the plant certainly can be summered outdoors if their moisture requirements can be met.



Their climate is tropical to subtropical, with dry, near desert-like conditions. It has an even longer dry season and low humidity almost year-round. Most of the moisture results from nighttime dews. Temperatures range from a maximum 40°C to a minimum 15°C. In cultivation, 18°C is the ideal minimum night temperature.



Catasetum expansum tolerate an environment with 40 - 60 % relative humidity during their growing season, but for optimal development of new growth and flowering, 70 % is recommended.

Substrate, growing media and repotting:

Catasetum expansum is best to grown in wooden basket with fir bark, osmunda, tree fern fiber, charcoal, and sphagnum, in various proportions or combined with still other ingredients such as sponge rock, perlite, leaf mold, peat, and bark screenings as substrate.

It is recommended to repot every year and never wait more than two years. The optimal time for potting or repotting is when new growth on a plant emerging from dormancy is about 5 cm tall and the nubs have developed into new roots that are reaching for support.
In its natural habitat it receives rainfall frequently even while dormant. The plant may be watered every sunny day during the growing season, provided conditions are such that they dry off relatively quickly. This species like to dry out at least slightly between waterings.



Fertilize with an appropriate formulation at least every week during the growing season, or fertilize with a weak formula every time the plants are watered. It is important to begin regular applications of high-nitrogen fertilizer (such as 10-5-5) with a full range of trace elements. As the leaves begin to unfurl, and well before flowering, add a high-phosphorus formula to develop big, strong pseudobulbs capable of producing robust inflorescences. Any of the soluble products with a large second-digit number (for example, 3-12-6) constitute a good source of phosphorus.


Rest period:

When the Catasetum expansum plants are leafless and no new growths are visible, the grower must respect their state of dormancy. Watering frequency should be reduced during dormancy. Fertilization should stop completely during this period. In the springtime, at the beginning of the growth cycle, water should not be made regularly available for the newly developing roots until the new growth is at least 5 cm tall.




In the stranger-than-fiction world of Catasetum flowers -where male and female flowers look so different that they were once classified as different species, and male flowers fire their pollen like missiles -it is the male flowers that are the peacocks and warrior princes with bold colors, sometimes elaborately fringed, toothed or spotted. Male Catasetum expansum flowers have an especially large shield shaped lip. In the center of the lip is a cavity, like a truncated spur, with thick fleshy walls. The cavity doesn't secrete nectar like a spur, but is a source of fragrance for fragrance-collecting Euglossine bees.


This week in our back up greenhouses, we have three different color forms of male Catasetum expansum flowers. First in this regiment is a handsome olive color form with a blood red center and plenty of red war paint. Release of the pollen masses is triggered by a touch to the downward pointing bristle in the center. In the photo above, notice that the flower in the upper left corner still has its pollen payload, while the flower in the center has already fired its two pollen masses.


Our second color form has pale green petals and sepals against a rich yellow-gold lip.


The most common form in our collection is a soft mint nonpareil color, to my eye the most soothing of the three. Catasetum expansum has a surprising range of color forms for a species with a relatively small distribution -northeastern Ecuador, where it grows as an epiphyte in seasonally dry forests from sea level to 1500 meters elevation.




Source:  http://www.theorchidcolumn.com/2016/07/catasetum-expansum-x-3.html








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