Darwin and Catasetum

[mcintyre63]

Here's a historical puzzle that I'm hoping someone familiar with the genus Catasetum can help to sort out. In 1862, Charles Darwin published a paper in the Journal of the Linnean Society called "On the Three remarkable Sexual Forms of Catasetum tridentatum" in which he described three orchids identified (at that time) as belonging to three different genera and concluded that they were male, hermaphroditic (perfect), and female flowers of one species. The full paper is available online; unfortunately, I can't find a link shorter than the 25 character limit, but if you Google the title of the paper, it should be one of the first results. I have attached the drawings that appeared in Darwin's paper of the three flowers.

The issue had been brought to Darwin's attention when someone reported finding all three flowers growing on one plant. Darwin examined flowers preserved in spirits, but not from the plant that produced all three forms; if I'm reading the paper correctly, he examined (using the names of the time) a single flower from Catasetum tridentatum and flowers of Myanthus barbatus and Monachanthus viridis that occurred together on one plant. He concluded that they were all C. tridentatum, and that the C. tridentatum flower he examined was male, the Myanthus barbatus flower was perfect, and the Monachanthus viridis flower was female. The question is, what are the modern names of the plants he examined?

According to Wikipedia (never authoritative, I know, but I don't have anything more authoritative to go on), Catasetum macrocarpum is synonymous with C. tridentatum and Monachanthus viridis (in various incarnations), but not Myanthus barbatus. Still according to Wikipedia, C. barbatum is synonymous with Myanthus barbatus and other incarnations of Monachanthus viridis. Using Google images, it is easy enough to find photos of male and female flowers of C. macrocarpum and C. barbatum, but I do not find any photos of C. macrocarpum that resemble the distinctive male C. barbatum (the bearded form that gives it its name), nor do I find photos of C. barbatum that resemble the male C. macrocarpum. The females of both species do look very similar, and it's easy to imagine how they could be confused for each other, particularly when preserved in spirits.

From all of this, I am guessing that the flowers Darwin examined were a male C. macrocarpum (his C. tridentatum) and a male and female C. barbatum (his Myanthus and Monachanthus). This theory, however, fails to explain the reports of all three flower types occurring on one plant.

In my efforts to resolve this puzzle, I've found a more recent paper reporting plants in the genus Catasetum that produce three types of flowers:

Gustavo A. Romero, 1992. Non-functional flowers in Catasetum orchids. Botanical Journal of the Linnean Society. 109 (2): 305-313.

Unfortunately, I only have access to the abstract, not the full paper, but from reading the abstract, it would seem that the flowers that are neither male nor female types are intermediate in form, not completely different forms. It's hard to imagine anyone describing a male barbatum-type flower as intermediate between the male and female forms of C. macrocarpum, or a male macrocarpum-type flower as intermediate between the male and female forms of C. barbatum.

Is there any chance, then, that the flowers Darwin examined all belonged to one species? Are there reliable modern reports of all three types of flowers (one resembling C. macrocarpum male, one resembling C. barbatum male, and one resembling a female of either species) occurring on one plant?

[King_of_orchid_growing:)]

I've never read the articles that Darwin wrote on the subject.

However, if I'm not mistaken, it is possible for a single plant to produce the three forms (or more possibly, 2 forms) of flowers mentioned.

If I'm correct, it has something to do with the amount of light exposure the plant receives that determines the sex of the flowers.

Should one plant have certain canes be in a certain position where it gets a certain amount of moderately bright indirect light, and another group of canes were in a certain position where it would get possibly something in the order of bright shade, then this might be the answer to your question.

[kavanaru]

Catasetum is one of the few genera that produces "male" and "female" flowers. Actually, what you have are flowers in which one of the sexes is "atrophiated" and non-functional. Sometimes, there is an error in the genetic translation during teh development ofthe flowers, and you can get "hermaphrotic" flowers. There is a lot of discussion whether these hermaphroditic flowers are fertile or not, and it seems that actually you can have all the range of fertility: 100% infertile, only male parts fertile, only female fertile, 100% fertile.

Normally, Male and Female Flowers are produce in separate spikes. And very often, not at the same time in teh same plant! Sometimes, however, it is possible to have both in one spike (some species do this more often than others!). Hermaphrodite flowers tend to appear more often on female spikes, but can also be found on male spike. And sometimes, you can have all of them on the same spike.

Male and Female flowers are so different, that in the past, they were described as belonging to different species. Normally, male flowers are very distinctive and easy to differentiate between species. Female flowers tend to be very similar within species, and you really need a very good trained eye to see the differences, and this is also not always possible! (similar Phenomena is to be seen in Cycnoches)

Now, back to Darwin, I have not read the article myself, but have heard abouts it. If the Photos you have posted are from this articles, here some names:

the drawing of Catasetum tridentatum is most probably Ctsm. maculatum. Wikipedia is right in the sense that Ctsm. macrocarpum (valid name) is synonym of Ctsm. tridentatum, however the drawing shown is not this species. The shown flower is "Male".

The Drawing of Myanthus barbatus, shows Ctsm. barbatum (or Ctsm. cristatum - this is a complex, which gives some ID problems, and some authors think they are the same species, being this very variable). The shown flower, however, is a "Male" flower and not a hermaphrodite! Monachanthus viridis is a synonym of Ctsm. barbatum.

The third drawing,Monachanthus viridis, shows actually (IMO) a hermaphrodite flower (The column is very masculine, and the border of the lip is not ver feminine). This flower shows very feminine features: general shape of labellum and petals placed backwards (together with that shape of labellum!), however looking in more detail, the labellum with that shape resembles the labellum of a "Male" Ctsm. planiceps (IMO; this is the species shown here), and as mentioned before, the column shows male features.. female columns are normally very short and round like in the pic below


Catasetum sp. female by afriorchids, on Flickr

[mcintyre63]

Thank you very much King_of_orchid_growing and Kavanaru. Kavanaru: Darwin identified the barbatum-type flower as hermaphroditic, though you are confident it was male. Given that Darwin was examining a flower preserved in spirits, and a male Ctsm. barbatum does have vestigial female organs, it's not hard to see how Darwin could have been mistaken on this point. Given that the Ctsm. maculatum and Ctsm. barbatum flowers Darwin described were both males, is it fair to say it's impossible for the two to appear on one plant? It seems a silly question, given that we're identifying them as two different species, but Darwin's conclusion was that they were the same species. In Darwin's defense, he did not report seeing all three flowers on one plant--he was acting on someone else's report, and the flowers he examined were from at least two different plants.

Here's one more way to put the question: Can a Ctsm. maculatum plant ever produce a flower resembling the male Ctsm. barbatum (or vice versa)?

[kavanaru]

Originally Posted by mcintyre63

Thank you very much King_of_orchid_growing and Kavanaru. Kavanaru: Darwin identified the barbatum-type flower as hermaphroditic, though you are confident it was male. Given that Darwin was examining a flower preserved in spirits, and a male Ctsm. barbatum does have vestigial female organs, it's not hard to see how Darwin could have been mistaken on this point. Given that the Ctsm. maculatum and Ctsm. barbatum flowers Darwin described were both males, is it fair to say it's impossible for the two to appear on one plant? It seems a silly question, given that we're identifying them as two different species, but Darwin's conclusion was that they were the same species. In Darwin's defense, he did not report seeing all three flowers on one plant--he was acting on someone else's report, and the flowers he examined were from at least two different plants.

I would need to read the original article to know exactly what heppened there. However. the main point here is that Darwin apparebntly worked with preserved flowers of no clear origin. In my text above, I was discussing what I could see on the drawings, and not directly what Darwing had done or not.

Originally Posted by mcintyre63

Here's one more way to put the question: Can a Ctsm. maculatum plant ever produce a flower resembling the male Ctsm. barbatum (or vice versa)?

if we speak about male flowers, YES it is impossible! it woul dbe like expecting a Cattleya mossiae producing flowers resembling Cattleya luteola... However, if we talk about female flowers, or even some hermaphrodites (tending to look like females), it is possible that the flowers are similar and some not trained could misidentify them...