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 (labellum) of the flower joined (adnate) 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 (and therefore do not quite meet Lindley's criteria for "Hormidium"), 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: