Knowles and Westcott (1838) first published the genus Prosthechea to include only P. glauca. However, the following year (1839) they changed the generic name to Epithecia because they felt that Prosthechea was too similar to another unspecified generic name. Examination of the generic names published in Index Kewensis reveals the very similar previously published generic name Prosthesia Blume (1826) (Violaceae). This may be the unspecified name that induced Knowles and Westcott (1839) to change the generic name from Prosthechea to Epithecia. Since Prosthechea is not a homonym of Prosthesia, the original publication is valid (ICBN, 2000). This new name is illegitimate (nomen illegitimum) since the previous name had been validly published and ought to have been accepted by the authors.
Epidendrum section Osmophytum was described by Lindley (1839) for plants with usually scented flowers. Subsequently, Lindley (1840) transferred P. glauca to Epidendrum, making the combination Epidendrum glaucum (Knowles & Westcott) Lindley thus recognizing Epithecia glauca Knowles & Westcott as a synonym and placing it in Epidendrum section Osmophytum. This combination is a nomen illegitimum since it is later homonym of Epidendrum glaucum Sw. which was transferred to Dichaea by Lindley himself. When Lindley (1853) published Folia Orchidaceae, he placed Epidendrum glaucum (Knowles & Westcott) Lindley in Epidendrum subgenus Encyclium, section Sarcochila, and not as previously classified in Epidendrum subgenus Osmophytum. Prosthechea glauca was subsequently transferred to Encyclia as E. glauca (Knowles & Westcott) Dressler & Pollard (1971) and assigned to Encyclia subgenus Osmophytum (Lindley) Dressler.
An ongoing systematic study of the genus Encyclia based on holomorphology has determined that the genus is neither morphologically cohesive nor monophyletic. In a preliminary molecular study, analysis of the internal transcribed spacer (ITS) sequences of nuclear ribosomal DNA supports the morphological conclusion that the Encyclia subgenus Osmophytum clade should be raised to the generic level because these species are sister to the Cattleya-Laelia clade not to Encyclia subgenus Encyclia. However, the monophyly of the three currently recognized subgenera of Encyclia, i.e., Encyclia subgenus Osmophytum, Encyclia subgenus Encyclia, and Encyclia subgenus Dinema, is supported by cladistic analysis of both morphological and molecular data.
Characters that distinguish Prosthechea (=Encyclia subg.
Osmophytum),
Encycliasensu
stricto (=Encyclia subg. Encyclia), and Dinema
(=Encyclia subg. Dinema), are listed in the following table;
generic synapomorphies are indicated in boldface type.
| Prosthechea | Encyclia s. s. | Dinema | |
| Pseudobulbs | fusiform,
often flattened |
usually ovoid or
conic-ovoid |
ovoid |
| Leaves | usually thin | thick | thin |
| Glycoside crystals | usually present | absent | absent |
| Inflorescence | prominent spathe,
with scape or sessile |
without spathe,
with scape |
conspicuous spathe, sessile |
| Flower | usually non-resupinate | resupinate | resupinate |
| Labellum callus | usually a thick pad | 2 fleshy ridges | 2 parallel ridges |
| Labellum adnate | half of column | usually at base | near base |
| Column | usually gibbous,
never winged |
not gibbous,
often winged |
not gibbous,
winged |
| Column midtooth | large, narrowly deltoid, ligulate, or subflabellate | short, usually broadly deltoid, | short, rounded, shorter than lateral teeth |
| Midtooth appendage | fleshy, knob-like, obtuse or truncate | absent | absent |
| Midtooth to anther | not appressed | appressed | appressed |
| Column sinuses | deep usually acute | broad shallow | shallow |
| Lateral teeth | stout | stout | petaloid |
| Seed capsule | 3-winged or sharply 3-angled | fusiform | ellipsoid |
| Capsule suture | covered by strap of tissue | strap absent | strap absent |
TAXONOMY: Species List