Hormidium


Within the Orchidaceae, Hormidium was originally a subgenus of the genus Epidendrum, but was later raised to a full genus. It is now considered not to be distinct from the genus Prosthechea, of which it is a synonym. Most of the species of Hormidium have been transferred to Prosthechea, although others are now classified in Encyclia, Epidendrum, Homalopetalum, and Lepanthes.

Taxonomy

In 1841, John Lindley used the name Hormidium for one of the subgenera into which he divided the genus Epidendrum. He described the subgenus as having pseudobulbous stems, sessile flowers and with the lip of the flower joined to the column. Later, in 1861, Heinrich Reichenbach concluded that the subgenus Hormidium was superfluous.
In 1883, George Bentham and Joseph Hooker raised Hormidium to a full genus. They distinguished Hormidium from the other pseudobulbous species of Epidendrum with at least a partially adnate labellum, and specifically mentioned only four species, two of which are now retained in Epidendrum, one which is now placed in Homalopetalum, and one which is now placed in Lepanthes. Because the genus Encyclia features non-adnate labella, and because the genus Prosthechea features labella which are only partially adnate, Bentham and Hooker's description is useful:
Hormidium is now considered not to be distinct from the genus Prosthechea, of which it is a synonym. Most, but not all, of the former species of Hormidium have been transferred to Prosthechea.

Species and synonymy

The following species have at one time or another been placed in the genus Hormidium but are now placed in different genera: