Catasetums
Max Hopkinson
Max began his talk by setting the scene about how he first became interested in the Catasetinae group, of which he now holds the UK National Collection. It was in 1981 during a visit to Florida that he obtained 6 plants from Jones & Scully – CITES regulations not being as forceful as they are to-day. At that time it was very difficult to obtain different Catasetum plants, although he did get three more from Wyld Court.
The Catasetinae group consists of five genera. Catasetum for which 130 species are defined, Mormodes with 48 species, Cycnoches with 32 species, Dressleria with 12 species and Clowesia with about 5 species. All species are low tropical epiphytes native to an area stretching from Mexico and Central America across Brazil and down through Argentina. In their native habitat they experience a generally dry period for several months when the plants lose their leaves and are dormant. In our northern hemisphere this corresponds to between November and March. During the hottest months plants have to withstand temperatures well over 100°F (38°C).
Max grows his plants with a minimum temperature of 60°F (16°C) although he said that down to 55°F (13°C) for short periods would not harm plants so long as they are dry. He waters weekly during growth using rain water whenever possible and he alternates feed at every watering between high nitrogen one week then high potash the next. Being heavy feeders he uses a solution of around 600 microsemens. He also adds something called “Nutrimate” (a natural product which contains very high levels of humic and fulvic acids) to his water which he said helps to boost the effect of the fertilisers. To avoid rot, watering after the rest period never starts until new growths are firmly established and approximately 4 inches long. Leaves are quite soft so constant vigilance against red spider mite is essential. A fogging system maintains humidity during the summer months. Plants are grown in containers which hang along wires close to the roof of the greenhouse for maximum light, but great care is necessary to avoid burning leaf tips behind glass. High light is crucial to stimulate production of female flowers.
Catasetinae are unique because a mixture of male, female and even hermaphrodite flowers can be present on any single spike. Male flowers are often quite showy and some, particularly Clowesias, have scents but all use a powerful sensitive trigger mechanism to shoot pollinia on to visiting insects, usually euglossine bees. If triggered falsely the sticky pollinia can travel a distance of about 3 feet. Female flowers of all species are much plainer, green and hooded. Flowers can be quite short lived. Spikes on Catasetums start from the base of their pseudobulb, whereas on Cycnoches they start from nodes mid pseudobulb and on Mormodes from the top of the pseudobulb.
For a long time Max re-potted annually but has found that every two years is just as satisfactory. He uses a mix of 50% sphagnum moss + 25% bark + 25% foam. He selects the foam very carefully to avoid any which has been treated with fire retardant which UK regulations require. Roots from previous years’ pseudobulbs are dead and have no useful function to the plant so he cuts those back at re-potting time, leaving just enough to anchor plants in their new mix until fresh roots can support new season growth.
Max showed many slides, beginning with several pictures demonstrating the extent of aerial roots in the natural habitat, and how when growing beside water the plants were larger at the bottom of a tree and gradually smaller higher up the trunk. There were also some pictures of spikes supporting multiple flower genders. Some natural hybrids like Catasetum x splendens being a mixture of C. expansum x C. pileatum were shown. Other slides showed C.saccatum var. Incurvum which was interesting because the lip curves round after a couple of days, and one of Max’s own hybrids where he had married two red flowered plants which produced a pale pink. The show included C. maculatum being the national flower of Costa Rica, and the brilliant shining red flower of C. Alex Pardoe “Celia”, a C. pileatum cross.
Flowers of Mormodes may last for 2-3 weeks and pictures demonstrated how the lip twists so that it is no longer in line with the pollinia. Cycnoches pictures included some huge flowers, Cyc. loddigesii for example with 8 inch flowers, but all showed very clearly the characteristic swan neck of the male flower column. A picture of a very recent discovery in 2000, Cyc. barthiorum, was included.
Max has only ever had one Dressleria, D.dilecta with a white flower, but that has since died.
The final pictures were of Clowesias which flower in winter after leaves have died, and he showed us the white striped flowers of Cl.warczewiczii, and the pale pink flowers of Cl. rosea.
In conclusion, Max said that he knows of only one intergeneric hybrid which has been made outside of this group of plants, which was between Galeandra and Cycnoches. Richard Baxter