Epidendrum, abbreviated Epi in horticultural trade, is a large neotropical genus of the orchid family. With more than 1,100 species, some authors describe it as a mega-genus. The genus name (from Greek, "upon trees") refers to its epiphytic growth habit. When Carolus Linnaeus named this genus in 1763, he included in this genus all the epiphytic orchids known to him. Although few of these orchids are still included in the genus Epidendrum, some species of Epidendrum are nevertheless not epiphytic.

Distribution and ecology

They are native to the tropics and subtropical regions of the American continent, from South Carolina to Argentina. Their habitat is mostly epiphytic, a few are terrestrial (such as E. fulgens) or rarely lithophytic (growing on bare rock, such as E. calanthm and E. saxatile). Most are to be found in the Andes, at altitudes between 1,000 and 3,000 m. Their habitat varies from humid jungles to dry tropical forests, from sunny grassy slopes to cool cloud forests.

Characteristics

They are quite varied in flower size and appearance. They grow in tufts, in racemose inflorescences, sometimes in corymbs or panicles. The apical, lateral or basal flowers are mostly small to medium in size and frequently are not marked by a conspicuous display. The inflorescences are frequently dense. Many species are fragrant. The flowers may be produced only once, or during several years from the same or new inflorescences. The ellipsoid fruits are 3-ribbed capsules.

This genus has the following characteristics :

• a slit rostellum (small extension or little beak to the median stigma lobe), producing a transparent or white thick and adhesive liquid.
• the sometimes fringed lip is adnate to (= united with) the column (forming a nectary tube (but rarely producing nectar), continuing through the pedicel). (The genus Prosthecia was split off because the lip is not completely adnate to the apex of the column.)
• the pollinarium contains 4 pollinia (with sometimes 2 very reduced pollinia), rarely only 2 pollinia.
• the erect, pendent, or creeping stems are reed-like, simple or branching, or may be pseudobulbs or thickened stems. (The genus Coilostylis, recently split off from Epidendrum, has pseudobulbs.)

Synonymy: A Confusing and Debatable Subject

Initially, European taxonomists applied the generic epithet Epidendrum to all newly discovered epiphytic orchids. Gradually, many of these "Epidendrums" were recognized as being quite diverse and deserving of different generic epithets -- many belong to different tribes or subtribes (e.g. [Vanda]]). To add to the confusion, however, many descriptions of closely related species were published with different generic epithets.

As if the confusion caused by these publications were not great enough, many closely related genera (or perhaps subgenera, sections, or subsections) have been recognized and published. According to the modern rules of taxonomy, each new proposed genus that is split off from Epidendrum must bear the name of the oldest generic epithet published for a member of the new genus. Hence, many genera which have been brought into synonymy with Epidendrum have later been segregated out again. Because most of these decisions rest on the informed opinions of authorities, the segregated taxa are often then re-published as synonyms. Hence, some of the following information may seem a bit contradictory, especially if the assertion that two names are "synonyms" is misconstrued as an assertion that the two names mean exactly the same thing.

The following genera have been brought into synonymy with Epidendrum:

• Amphiglottis Salisb.
• Anacheilium Hoffmanns.
• Anocheile Hoffmanns. ex Rchb.
• Auliza Small
• Coilostylis Raf.
• Didothion Raf.
• Diothonea Lindl.
• Dothilophis Raf.
• Doxosma Raf.
• Epicladium Small
• Epidanthus L.O.Williams
• Epidendropsis Garay & Dunst.
• Exophya Raf.
• Hemiscleria Lindl.
• Kalopternix Garay & Dunst.
• Lanium (Lindl.) Benth.
• Larnandra Raf.
• Microepidendrum Brieger (nom. inval.)
• Minicolumna Brieger (nom. inval.)
• Nanodes Lindl.
• Neolehmannia Kraenzl.
• Neowilliamsia Garay
• Nyctosma Raf.
• Phadrosanthus Neck. ex Raf.
• Physinga Lindl.
• Pleuranthium Benth.
• Pseudepidendrum Rchb.f.
• Seraphyta Fisch. & C.A.Mey.
• Spathiger Small
• Stenoglossum Kunth
• Tritelandra Raf..
  

Genera which have been erected (or resurrected) from Epidendrum include the following examples:

• Anacheilium (Lindl..) Withner & P.A.Harding 2004. This genus contains more than 50 species, reclassified from Prosthecia, Encyclia, and Epidendrum.
• Barkeria
• Dimerandra
• Caularthron
• Coilostylis (Raf.)Withner & Harding
• Encyclia This is another "mega-genus" differing from Epidendrum in that the plants are mostly pseudobulbous, and in that the lip "encircles" the column, rather than being adnate. Like Epidendrum, genera have been and are likely to continue to be split off from this genus.
• Euchile (Dressler & G.E. Pollard) C.L. Withner 1998 was elevated from a section of Encyclia with two species.
• Hormidium Lindl. ex Heynh, described by Brieger as having the lip adnate to the proximal part of the column. Brieger placed more than 100 species in this genus. (Lindley was unsure if this was a genus, subgenus, or section.) Withner and Harding recently transferred two more species into this genus: one from Epidendrum and one from Encyclia.
• Microepidendrum Brieger ex W.E.Higgins 2002
• Nanodes
• Oerstedella Rchb.f.
• Oestlundia W.E.Higgins 2001
• Panarica Withner & P.A.Harding 2004 contains five species, some from Prosthecia and some from Epidendrum
• Pollardia Withner & P.A.Harding 2004 contains seventeen species, some from Prosthecia and some from Epidendrum.
• Prosthecia This debatable genus contains the "cockleshell orchids", with lips which are adnate to the column only about halfway to the apex, and which "encircle" the end of the column. Most of the species of this genus were long classified in Encyclia. Some species of this genus have been placed in Anacheilium (Lindl.) Withner & P.A.Harding 2004 and Panarica Withner & P.A.Harding 2004.
• Pseudencyclia Chiron & V.P.Castro 2003
• Psichylus

Species

Epidendrum sensu latu is a huge genus, embracing more than 2,000 binomials (about 1,100 accepted names and the rest have become synonyms of other species). More than 1,000 have been split off into new or resurrected genera. However, it is estimated that there are more than 2,000 Epidendrum orchids, many of which still have to be discovered. More than 400 new species have lately been described by Eric Hágsater and colleagues (see: Reference).

Several botanists have been honored with an Epidendrum orchid named after them, including the following:

• E. carnevalii Hágsater & L.Sánchez, (1999). (named after Carnevali)
• Epidendrum dunstervilleorum
• E. foldatsii Hágsater & Carnevali, (1993). (named after Foldats)
• E. garayi Løjtnant, (1977). (named after Garay)
• E. garciae Pabst, (1976). (named after Garcia-Cruz)
• E. hagsateri Christenson, (1995). (named after Hágsater)
• E. lueri Dodson & Hágsater, (1989). (was named after Dr. Luer of the Missouri Botanical Gardens, author of the series of monographs about the Pleurothallidinae orchids, the Icones Pleurothallidinarum)
• E. schlechterianum Ames, (1924). (named after Rudolph Schlechter)
• E. schweinfurthianum Correll, (1947). (named after Schweinfurth)

Hybrids

Only a few natural hybrids have been named, such as Epidendrum × doroteae, Epidendrum × gransabanense and Epidendrum × purpureum.
Epidendrum orchids hybridize readily with members of the genus Cattleya (Epicattleya is the accepted nothogenus for such a hybrid) and other related genera. It is not uncommon for one to come across multi-generic hybrids, for example, Adamara is the nothogenus for a hybrid containing ancestor species from each of the genera Brassavola, Cattleya, Epidendrum, andLaelia, but no others. (For several decades, the nothogenus Yamadara was used to mean Adamara.)

Culture

Although the flowers of many Epidendrum species are rather small and not very showy, many are nevertheless widely cultivated, such as E. cinnabarinum, E. ibaguense, E. nocturnum, E. radicans, E. secundum, and a multitude of hybrids of these species.

Most Epidendrum species require intermediate to warm conditions for culture, although a few of the commonly cultivated species, such as E. radicans grow in cool conditions. Some, such as Epidendrum magnoliae syn. conopseum can even tolerate extended freezing conditions. In Auckland and other sub-tropical regions of New Zealand, the cool growing plants will flower all year round. While they are normally grown in pots, it is also possible to grow them in a bark garden or on a tree.

References

1. Brieger, F. C. and Hunt, P. F. "HORMIDIUM, MAXILLARIA AND SCAPHYGLOTTIS (ORCH.)", Taxon 18(5) pp. 601-603 (Oct. 1969)
2. Hagsater, E., Sanchez Saldana, L., and Garcia Cruz, J. (eds.) 1999. Icones Orchidacearum: fascicle 3. The genus Epidendrum: part 2. "A second century of new species in Epidendrum". Herbario AMO, Mexico D.F.
3. Hagsater, E. 2001. Icones Orchidacearum: Fascicle 4. The Genus Epidendrum. Part 3, "A Third Century of New Species in Epidendrum". Asociacion Mexicana de Orquideologia A.C., Mexico, D.F.
4. Hágsater, E. 2004. The genus Epidendrum. Part 4. A fourth century of new species in Epidendrum. Icon. Orchid. 7: pl. 701-800.
5. Withner, C. A., Cattleyas and Their Relatives. Brassavola, Encyclia, and Other Genera of Mexaco and Central America (5) Timber Press, 1998
6. Withner, C. A. and Harding, P. A., Cattleyas and Their Relatives. The Debatable Epidendrums Timber Press 2004.

External links

• Reed-stem Epidendrums