Oncidium Sw.

Who has not seen at least one Oncidium? Those “Dancing Ladies” orchids are quite a common sight and they look indeed like a whole cloud of little (mostly yellow) doll-shaped flowers, swaying in the slightest breeze. The name Oncidium comes from the Greek word ‘oncos’ which means growth, swelling or wart and refers to the odd-shaped protuberances on the lips of these flowers.

The Oncidiums are a large group that is constantly being revised. They are closely related to Odontoglossums and Miltonias (plus others) and are frequently used for hybridizing because of their free flowering habit. All these plants come from the New World but of course now are growing in collections all over the world.

Some of their names are translated as

Oncidium Wilmore

The plants from this genus have been collected for a long time. One of the first ones to arrive in England in about 1760, the very floriferous Onc. altissimum was brought by the (in)famous Captain Bligh – you have heard of the ‘Mutiny of the Bounty’? Well, this was not from that sad voyage and the plants arrived quite safely. They eventually were doing so well in England that someone actually complained that “- these plants (Oncidiums) are more difficult to kill than to keep alive!”

There are Oncidiums for every kind of growing environment; there exist so many different species in so many different places that anybody can probably grow at least one of them. Onc. bifolium for instance even started to bloom in the transport ship’s cabin, while boxed up from South America to England. Onc. bracteatum is found at extremely high altitudes in Costa Rica and Panama: 6,000 to 7,000 meters elevation; We can surmise that it will do well in cool conditions. Onc. microchilum grows on rocks in high mountain passes in Guatemala, so it probably needs lots of sun. Onc. nanum lives on hot and humid riverbanks in Guyana – perhaps this might prove to be a challenge for most of us!

One of the most interesting bits of information I learned from George Verboonen about Onc. onustum (now Zelenkoa onusta): it grows so profusely on the dry coastal hillsides in (?) Ecuador and Peru that the natives call it “Leche di cabra”, meaning “Goats’ Milk”, and where it grows – or grew, the goats were eating it up, along with everything else.

Another charming tale I heard from our friend Johanna DeLeeuw: While they were on a trip to Guyana, they were taken on a boat-ride along a river. The vegetation overhead was so dense that they could not see the sky. And in this gloom of foliage, there were long trailing chains of the little golden Onc. globuliferum.

One group of Oncidiums which many people don’t care for include the unusual Onc. heteranthum. It makes long inflorescences with lots of twiggy growth and very scant flowers at the ends of some twigs. Most of the stems end without buds or flowers. Now that could be frustrating, however, I think that all the side branches and twigs look like fine, pale gold-green filigree, into which a few large yellow blooms have been laced, like jewels.

There are so many different kinds – do try at least one!

Ingrid Schmidt-Ostrander - Canadian Orchid Congress