Prosthechea

Prosthechea is a genus in the orchid family (Orchidaceae). The name is derived from the Greek word prostheke (appendix), referring to the appendage on the back of the column. Appendage orchid is a common name for this genus.[2]

Prosthechea
Prosthechea cochleata
Scientific classification
Kingdom:	Plantae
Clade:	Tracheophytes
Clade:	Angiosperms
Clade:	Monocots
Order:	Asparagales
Family:	Orchidaceae
Subfamily:	Epidendroideae
Tribe:	Epidendreae
Subtribe:	Laeliinae
Genus:	Prosthechea Knowles & Westc., 1838
Type species
Prosthechea glauca Knowles & Westc. - Floral Cabinet 2: 111-112. 1838.
Species
About 100 species - See text
Synonyms[1]
Epithecia Knowles & Westc., illegitimate superfluous name Hormidium Lindl. ex Heynh. Anacheilium Hoffmanns. Epicladium Small Euchile (Dressler & G.E.Pollard) Withner Pseudencyclia Chiron & V.P.Castro Panarica Withner & P.A.Harding Pollardia Withner & P.A.Harding

The genus Prosthechea has only recently (1997; published in 1998) been reestablished by W. E. Higgins as a distinct genus (see references). Two species were later transferred to Euchile (E. citrina and E. mariae) by Withner in 1998.[3] The status of Euchile species as sister to Prosthechea excluding Euchile was confirmed by Higgins in his doctoral dissertation in 2000.[4] Previously, the species had been included in different genera : Anacheilium, Encyclia, Epidendrum, Euchile, Hormidium and Pollardia. The status as genus was confirmed by recent data, based on molecular evidence (nuclear (nrITS) and plastid (matK and trnL-F) DNA sequence data) (W. E. Higgins et al. 2003).

This a neotropical epiphytic genus, widespread across much of Latin America from Mexico to Paraguay, as well as in Florida and the West Indies.[1][5]

The roots of all Prosthechea species possess a velamen (a thick sponge-like covering) differentiated into epivelamen and endovelamen. Flavonoid crystals were observed in both the roots and leaves. The erect stems form flattened or thickened pseudobulbs. There are 1 to 3 terminal, sessile leaves. The leathery blade is ovate to lanceolate. (Euchile leaves are softer and thinner than other Prosthechea leaves.)

The flowers form an apical, paniculate raceme with a spathe at the base of the inflorescence . There is a great variety in the flowers of this genus. They may be attached to the stem by a peduncle or may be sessile. They can flower on the raceme at the same time or successively. They can be resupinate or non-resupinate (as in Prosthechea cochleata). Prosthechea flowers are unique among the Laeliinae in producing fluorescent flavenoid crystals when preserved in ethanol with 5% sodium hydroxide.[6]

The sepals are almost equal in length, while the petals can be much slender. The lip is pressed closely (adnate to proximal) to half of the column and shows a callus (a stiff protuberance). The column is 3- to 5-toothed at its top.

There are four, almost equal pollinia with an inverted egg shape. There are four stalks (or caudicles) in two pairs. The beak is entire, curved into a half circle and covered with viscous glycoside crystals.

The fruits consists of ellipse-shaped to egg-shaped, 1-locular, 3-winged capsules.