Catasetinae for identification Part 1 Catasetum

Starting just before Christmas, I have received pictures of an interesting assortment of flowers of the Catasetinae. The first on the list was the Mormodes colossa already discussed on my last blog of 2009 about Panamanian Mormodes. The next was a Catasetum from Mark Pendleton. Mark manages the boarding department of Brookside Orchids in California. He explained many plants show up in his department with no source data and this was one of those plants. This answered my first basic question when I receive a picture of an unidentified flower – the origin of the plant, including, if known, the country. The original pictures sent were female flowers. The female flowers of all Catasetum are so similar that it is nearly impossible to identify the flower from them. Catasetum, like the sister genus Cycnoches, are identified from the male flowers. After the original pictures of female flowers were received, fortunately the plant bloomed with male flowers and Mark sent this picture to me. I decided to take this opportunity to explain my methods of identifying flowers of Catasetum. The usual method to identify a flower of any orchid is to receive one or more flowers either dried or preserved in alcohol plus any pictures and information the owner has about the plant. In some cases it is possible to identify the flowers from pictures and information about the plant without actually examining a flower. Knowledge of the genus, research into the literature and pictures available are the tools to identify what one has. In this case it has been possible to identify the flower from the pictures without requesting a flower.

When identifying a Catasetum the first part of the flower I examine is the position of the antennae – the so-called “triggers” on the male column which, when touched, serve to expel the pollen onto the Euglossine bee that will deliver it to a female flower. Because the antennae are very sensitive, any touch will expel the pollen. The genus Catasetum is divided into two subgenera: Pseudocatasetum and Catasetum. Under the current rules of taxonomic nomenclature, if a genus is divided into parts, the part that contains the first species identified and on which the genus is based (the type species), always carries the generic name – in this case Catasetum. The type species of the genus is Catasetum macrocarpum and so the subgenus containing it is currently named Catasetum. The subgenus Pseudocatasetum contains only two to five species, depending on how the species are identified. The antennae of its male flowers are quite short, almost vestigial. The remainder of the some 160-180 species of the genus Catasetum are in the subgenus Catasetum.

The subgenus Catasetum is in turn divided into two sections based on the position of the antennae. Section Catasetum is based on the type species of genus, Catasetum macrocarpum. This section was originally named Anisoceras by the German taxonomist Mansfield for the asymmetric arrangement of the antennae as can be seen in this picture. These are also called “crossed” antennae. One antenna is straight and the other bent at a right angle either over or under the straight antenna. In addition to the type species, there are approximately 15 additional species and natural hybrids in the section. The second and by far largest section of the subgenus contains the remaining species of Catasetum. This is the section Isoceras consisting of the species with symmetrically arranged antennae such as shown here on Catasetum cristatum. This section has several subdivisions which I am not going to describe at this point. Anyone who is interested can contact me.

Now let’s look at the antennae of the flower sent by Mark. I have cropped the original picture to show a close-up of the lip, column and the antennae and I have also lightened the picture to show the detail of the lip. As can be seen, the antennae don’t match either of the two sections, asymmetric (crossed) or symmetric. This led me to think that this might be a hybrid between the two sections. Flowers of hybrids normally vary in their shapes between the parents. To see if this was true in this case, I asked Mark for pictures which would show additional male flowers to check for variation among them. Mark sent me a picture from the previous year flowering and as I suspected, the antennae in the flowers were all different. To me this confirmed that we were dealing with a hybrid and not a species. The question is what species? This frequently is an almost impossible task to determine the species parents of a hybrid. In this case however, I was fortunate that the shape of the inner edges of the lip was very distinctive. There are four species who have this type of lip, but the most commonly used in hybrids is Catasetum sanguineum. Also, as the name indicates, Ctsm. sanguineum has red markings on it as does this hybrid. Among Catasetum hybridizers, Catasetum sanguineum is known to be very dominate in its progeny, a feature that can mask the other parent. Because Catasetum sanguineum has symmetric antennae and as I had determined first, the hybrid shows it is a intersectional hybrid, this means that the other parent should come from the relatively small group of 15 species in the section Catasetum so now we have a better chance to identify the other parent. With the possibilities narrowed, I reviewed the registered hybrids of Catasetum sanguineum with parents from the section Anisoceras and found a picture in the AOS awards of Catasetum Jumbo Eagle ‘Linda Livesay’ HCC/AOS which very closely matches Mark’s flower. I felt comfortable identifying Mark’s flower as a clone of Catasetum Jumbo Eagle. There are several other awards to this hybrid of Catasetum sanguineum X Catasetum expansum. These awards plus Mark’s plant are an interesting study in the variability among different plants of the same parents.

I hope that the information has been of interest and helpful to anyone trying to identify one of their plants. I will continue this series next with a Mormodes from Venezuela.