In this topic we’ll talk about Catasetum alliance orchids or Catasetum type orchids. Catasetum alliance represents several orchid genera with similar biology and thus similar growth and care requirement.
Prominent features of catasetum type orchids
These orchids are famous, and not only for their exceptional beauty. Some biological features of these orchids are so amazing and unusual (even for such unusual plants as orchids) that Darwin wrote his book “Fertilization of Orchids”, discussing Catasetums. The first thing to consider about Catasetum Alliance orchids (including closely related genera Catasetum, Cycnoches, Mormodes and Clowesia) is that these orchids have unisexual flowers – which is not common for orchids. Most prominent genus (Catasetum) has male and female flowers which differ tremendously from each other. In the past, botanists thought that specimens, simply bearing flowers of different sex, belong to different species and even genera. And only Darwin has made clear that they do belong to the same genera and species, just having male and female flowers. A plant may produce both male and female flowers at the same time (and even on the same inflorescence) but cannot produce hermaphroditic ones.
The most prominent difference between male and female flowers in Catasetums is that male flowers are bright, fancy colored and have interesting shapes, while female flowers of Catasetums are greenish, not so interesting and don’t much differ among different species. Cycnoches and Mormodes have fewer differences between male and female flowers, while Clowesia is only one genus of Catasetum alliance which has hermaphroditic flowers. The second feature of Catasetum alliance orchids, which is quite bizarre, is that these orchids have unique pollen ejection structure, allowing to simply blast their pollen up to 8 feet (Catasetum saccatum). Catasetum has some sort of a hook inside its lip which causes “shooting” the pollen with some force when being pressed by an insect. Sticky disk flies up striking the insect and sticking to it. It is possible to feel some recoil from this “shot” if touching the hook with a pencil, imitating an insect.
The third unique feature and very interesting feature indeed is that the natural pollinators of Catasetum orchids are actually male bees (drones), who are attracted to flowers by feromones, which are produced by male flowers. These feromones have a nearly narcotic effect on male bees – the drones really desire for flowers, trying to gain as much feromone as possible. Immediately after pollen is blasted, the flower stops produce feromone, and male bees with pollen on their bodies have to fly to a female flower, which starts producing the same feromone. Catasetum orchids are ones of few plant genera in the world which are using bee drones in pollination. So, these orchids are not only beautiful but also they are true plant curious and could become a gem of every orchid collection.
Diversity of Catasetum alliance orchids
Catasetum, Cycnoches, Mormodes and Clowesia are sympodial orchids with cigar-shaped pseudobulbs. They are growing in warm and hot seasonally dry forests of America, either epiphytical or terrestrial, and they have deciduous leaves in the upper part of a pseudobulb. Catasetums are large, while Mormodes and Clowesia are medium sized orchids.
Catasetum pileatum (called Mother of Pearl Orchid) has astonishing red, white or green more than 4 inches wide flowers; it was a floral emblem of Venezuela before Cattleya mossiae. Catasetum barbatum has fancy bearded lips, Catasetum bicolor has fragrant large flowers, and flowers of Catasetum gnomus resemble in shape a gnome. Catasetum imperiale has splendid pink large flowers and is used excessively in hybridisation, and Catasetum maculatum has exotic, spotted flowers. Catasetum tenebrosum has effective flowers with black petals.
Cycnoches, or Swan orchid, also contains extremely lovely species such as Cycnoches cooperi, Cycnoches warscewiczii, Cycnoches egertonianum, Cycnoches loddigesii, Cycnoches peruvianum, Cycnoches pentadactylon and Cycnoches lehmannii and differ from Catasetum for having a long column in male flowers, resembling swan neck.
Mormodes genus resembles Catasetum except for the fact that inflorescences of Mormodes come from the middle of pseudobulb, whereas Catasetum has its inflorescences in a basal part of a pseudobulb. Mormodes atropurpurea has dark purple splendid flowers, Mormodes aurantiaca has yellow-orange with purple spots flowers, Mormodes buccinator has beautiful bright yellow flowers, and Mormodes igneumis has fire-red ones.
Clowesia doesn’t have unisexual flowers; its flowers are actually hermaphroditic but exceptionally lovely. Clowesia rosea has lovely white-pink numerous flowers, Clowesia dodsoniana has white-green tender flowers, and Clowesia warczewitzii has large, extremely fancy white with yellow flowers.
Also, there are many beautiful hybrids in this group of orchids. For example, Fredclarkeara is a complex hybrid between Mormodes, Clowesia, and Catasetum, which has astonishing dark purple or black flowers.
Growing and care
What’s about Catasetum type orchids care – it’s not very difficult but has important peculiarities. First, you should keep in mind that these orchids have dry and warm strict dormancy when they drop their leaves and do not grow at all. When (usually at spring) new growth is visible, you should pot your orchid to a container with a substrate, made of medium bark, sphagnum moss, and cocoa chips, and do not water your orchid until new roots are clearly visible (watering not in proper time could cause rotting). Then, when new roots are about 2-3 inches in length you should begin watering and gradually increase it. When your orchid is actively growing and has at least two forming leaves, it needs plenty of light (Cattlea level of light), warmth, ample watering (which is crucial) and a lot of fertilizers with high Nitrogen content. Catasetum type orchids are heavy feeders – they are extremely fast growers because in nature they have a relatively short rain period and have to grow large pseudobulbs in a short period of time.
Some orchid enthusiasts suggest that in order to make Catasetum orchid produce showy and beautiful male flowers you need to put the orchid into not very optimal conditions for its growing, for example, put the orchid in conditions with reduced light level. And if the Catasetum orchid grows in optimal conditions it will tend to produce not showy female flowers.
When leaves of the orchid become to turn yellowish, it is a sign that your orchid starts getting dormant. At the same time, you may see yellow and green leaves on the same plant. At this point, you should start gradually reducing watering, light, fertilizers and temperature. When orchids have dropped leaves completely – don’t water at all. You can put orchids which are complete dormant into a closet because dormant Catasetums don’t need light at all. Some orchid enthusiasts took them away from pots and cut off roots (because they are dying and new growth produces new roots at spring), and you can also cut backbulbs so they will produce new growth next growing season.
by Kawamoto Orchid Nursery
The World of Catasetums
Arthur W. Holst