Unidentified:help please

[maggs]

I have this orchid that I found in my old mango tree about three years ago, it is grows as one single plant and I have three of them, all are in bloom now but the flowers are small and a very pale pink, this is the second time it has bloomed and I do not know the name, I would love if perhaps it could be identified, I used a piece of mango tree and some coconut husks and I have got them in an apple tree, (golden apple, pomme cythere,malay apple) are just some of the names of the fruit.

[max]

I can't help with the id but its very pretty.

[serama]

That's Caularthron bicornutum, a species native to most of Central America, including the West Indies. It's a medium-sized species that likes it hot, fairly bright (direct sun for some of the day) and on the dry side. It grows best mounted or in baskets, if you decide to take some off the tree and grow some of it in a pot, you must give it excellent drainage.

[mauraec]

If it's Caul. bicornutum, it should be very fragrant as well.

[PaphMadMan]

The shape of the lip, lack of spottiing on the lip, and the flowers described as pale pink and small... this is probably Caularthron bilamellatum, not Caularthron bicornutum. Both could be found in Trinidad-Tobago. They are similar in many ways, and Caularthron bicornutum is much better known in general, so it isn't surprising that it was suggested. Both should be fragrant.

[maggs]

I am very glad that I have found this because I have four plants each with a spike, and then this afternoon I went looking up into the mango tree again and found two small ones but one had been eaten out by ants, the other one I put into some insecticide and mounted it on a piece of sapodilla branch,but I think I will put that into a pot as it is very young and green, I scout alot under the fruit trees at the back yard. Thanks for the information.

[serama]

UPS! You're right Kirk, I never even thought of checking if there were related species to Caularthron bicornutum, probably because it is the only species in the genus we ever see in cultivation over here.

Brenda, don't worry about the ants. These plants have a natural symbiotic relationship with ants just like other related orchids such as Myrmecophila spp. do. The ants won't actually damage the plant and they're not trying to eat it. Certain ant species have co-evolved with these plants and they have adapted to search out these orchids, as they live inside the hollow pseudobulbs and provide the orchid with protection from other insects or small animals that might try to eat it, while the plant gives them somewhere to live. The plant can live without the ants, if you're hellbent on getting rid of them, but if you leave them outside after getting rid of the ants, they will be re-colonised by ants sooner or later as that's how they grow in nature.

[maggs]

Thanks Serama, that is interesting about the ants, but then how can the plant really survive when it is occupied by ants that leave a funny looking stuff there? but tell me is this family to dendrobiums? I ask that because of the pseudobulb and also the canelike look that is similar, and I did not really notice ants on them since I have had them because I spray from time to time with insecticide to get rid of other insects too and keep some snakes away, I will take note of this though

[serama]

Brenda, the genus Caularthron belongs to the Laelinae and is related to Cattleya, Laelia and Epidendrum among others, but not to Dendrobium (which is native to Asia, the pacific islands and Australia), though I can see how the shape of the plant might look more like a hard-cane dendrobium than a cattleya relative.

There are many different plants that enlist ants to defend them against other animals. Among the most famous are certain acacias (e.g. Acacia cornigera), ferns (e.g Lecanopteris celebica) and a group of epiphytic plants known as mymecophytes (which means "ant-loving" in greek). Most of these plants can live without the ants, but grow better when inhabited by them, as the ants provide protection from herbivores and fertilise the plants with their droppings (some of the plants have specialised tissues that absorb nutrients from the dropping the ants leave inside their stems). For some plants the relationship is so important that they can't live without the ants (e.g. certain Macaranga species). Certain ant species are only found living in plants and nowhere else and some of them only inhabit a single species of plant.

Some of these plants give the ants shelter in the way of specialised organs (hollow stems and even thickened hollow spines or leaves) and sometimes food (nectar from special glands on leaf axils rather than from flowers is the most common adaptation to feed ants, though some acacias go even further and provide special protein parcels at the end of their leaf tips for the ants). The ants in return protect the plant from herbivores such as other insects and even large animals are driven off by them, including antilopes and giraffes, as some of the ants have very painful bites and stings. One plant (I can't find the exact reference for this small tree) has an obligate relationship with an ant species where the ants not only protect the plant from animals but even kill all other plants that grow within several meters of their host plant by continuously biting and injecting them with formic acid until they die, thus giving their host the best access to nutrients and light by killing all other competitors.

Among orchids there are several that often house ants within their root ball. These orchids have thin hard roots that grow outwards making a structure that looks like a sea urching/porkupine. These root balls trap falling leaves, etc... giving the orchid extra nutrients, but also provide shelter for ant colonies. This happens to all species in the genus Coryanthes (the bucket orchids). Other orchid genera that go even further and provide hollow stems for ants to live in include Myrmecophila and Caularthron. These have very thick, cane-like pseudobulbs that are hollow and have a slit/opening at their base and thus allow ants to live inside them. By the way, Caularthron and Myrmecophila are closely related genera and can be found in very much the same kind of habitat and both have their centre of distribution in central america and the caribean islands.

I hope this answers some of your questions.

[eircsmith]

These are the images of a ‘Caularthron bicornutum’ orchid. They are mainly found near sea and rivers on rocky cliffs of Brazil, Colombia, The Guiana, Trinidad-Tobago and Venezuela. These orchids are intermediate to warm temperature loving orchid species.