AFRICAN

ORCHIDS

Angraecum Bory, Voy. îles Afrique 1: 359 (1804).
Synonyms:
Angorchis Thouars, Nouv. Bull. Sci. Soc. Philom. Paris 19: 318 (1809), nom. illeg.
Aerobion Kaempf. ex Spreng., Syst. Veg. 3: 679 (1826).
Macroplectrum Pfitzer in H.G.A.Engler & K.A.E.Prantl (eds.), Nat. Pflanzenfam. 2(6): 214 (1889).
Bonniera Cordem., Rev. Gén. Bot. 11: 416 (1899).
Lepervenchea Cordem., Rev. Gén. Bot. 11: 415 (1899).
Pectinaria (Benth.) Cordem., Rev. Gén. Bot. 11: 412 (1899).
Ctenorchis K.Schum., Just's Bot. Jahresber. 27(1): 467 (1901).
Monixus Finet, Bull. Soc. Bot. France 54(9): 15 (1907).
Dolabrifolia (Pfitzer) Szlach. & Romowicz, Richardiana 7: 54 (2007).
Description:
The genus Angraecum was established in 1804 by Colonel Bory de St. Vincent. The name derives from a Malayan word, angurek, used for epiphytic orchids with growth similar to that of Vanda. Angraecum is a large genus of about 206 species, about a quarter of which occur on mainland Africa, with the rest growing in Madagascar and other Indian Ocean islands, except for A. zeylanicum, which is found in Sri Lanka as well as the Seychelles. As Angraecum was one of the first genera of African orchids to be described, many species that are now placed in other genera such as Aerangis, Jumellea, and Rangaeris were originally described as Angraecum.
The genus Angraecum is by far the largest genus of the alliance, with more than 200 named species—over 125 of them from Madagascar. Moreover, when we consider the basic criteria on which orchids are judged—flower size, beauty, and lasting qualities—this genus is the most distinctive of the orchids. Even though perhaps half of the large number of known Angraecum species may be of little more than passing interest to hobbyists because of their small plant or flower size, the remaining species form a most interesting group with highly diverse and intriguing vegetative and floral characteristics. Plants vary in height from a couple of inches to 6 feet (1.8 m) or more, and are equally variable in stern length, leaf style and arrangement. Flowers range in size from minuscule to a spread of about 8 inches (20 cm). The inflorescences carry from one flower to many, most of them with conventionally downturned (inferior) tips, but a significant number with lips that are upturned (superior). Large plants or small, flowers few and large or many and small, each has its unique qualities and is fascinating in its own way. The only traits that unfailingly prevail from one species to the next are the white flower color— sometimes replaced by green, brown, or amber in one or more of the segments—and the broad, concave lip.
Most Angraecum´s are epiphytic, although a few are lithophytic or semi terrestrial. Their leaves are mostly leathery, linear, tongue- or strap-shaped, jointed at the top of the sheath, and to some extent unequally obtusely bilobed at the tip. The inflorescences emerge from the axils of the leaves and are one-or more-flowered. Dorsal sepals and petals are free, and the lateral sepals and petals do not extend forward and outward like those of the Jumellea species. Their lip is entire, or rarely lobed, shell- or keel-shaped, the base usually enveloping the column, and the fiat portion, or blade, forming the spur. The column has no "foot," and the clinandrium (the cavity between the anther sacs) is shallow and deeply bilobed in front, with a tooth like rostellum in the middle. There are two pollen masses, or pollinia. The ovary may be stemmed (pedicellate) or unstemmed (sessile).

Notes:
Dr. Leslie A. Garay has undertaken a further revision of the genus Angraecum in an article entitled "Systematic of the genus Angraecum (Orchidaceae)" appearing in the Kew Bulletin (1973). After reviewing the approximately 550 binomials in the genus, he recognizes 19 sections, 3 of which he has established.
The 19 sections of Angraecum listed by Dr. Leslie A. Garay are as follows:
Angraecum section Acaulia Garay
Angraecum section Afrangraecum Summerh.
Angraecum section Angraecoides (Cordem.) Garay
Angraecum section Angraecum
Angraecum section Arachnangraecum Schltr.
Angraecum section Boryangraecum Schltr.
Angraecum section Chlorangraecum Schltr.
Angraecum section Conchoglossum Schltr.
Angraecum section Dolabrifolia (Pfitzer) Garay
Angraecum section Filangis Garay
Angraecum section Gomphocentrum (Benth.) Garay
Angraecum section Hadrangis Schltr.
Angraecum section Humblotiangraecum
Angraecum section Lemurangis Garay
Angraecum section Lepervenchea (Cordem.) Garay
Angraecum section Nana (Cordem.) Garay
Angraecum section Pectinaria Benth.) Schltr.
Angraecum section Perrierangraecum Schltr.
Angraecum section Pseudojumellea Schltr.
As an aid to identification have I set a key to sections of Angraecum, so you better can find the description of the species you looking after.
It should be noted that DNA studies for this genus are currently under way, and the resultat may provide new insight into the way in which the species are classified. Some may be transferred to other sections or even to new genera when the resultat of the new work are coordinated and combined with information from traditional sorurces.
Habitat:
Many species of Angraecum orchid are considered to be at risk of extinction in the wild and are protected from international trade under CITES. The genus Angraecum is listed as one of the top conservation priorities by the International Union for Conservation of Nature and Natural Resources (IUCN) Orchid Specialist Group. Many of the species, such as Angraecum sororium, are endemic to Madagascar and are threatened from over collecting, loss of hawkmoth pollinators, habitat fragmentation, and fire.
Distribution:
Tropical Africa and Madagascar contain the majority of the genus with one outlier found on Sri Lanka, and three species once thought to belong to the genus in Japan and the Philippines. But these orchids can also be found on the Comoros, the Seychelles, and the Mascarenes. They occur between sea level and 2,000m in humid regions.
Cultivation:
Because there is such diversity in the genus, it is difficult to give any general advice on cultivation, except to say that most are forest species and appreciate fairly dense shade and high humidity. All are epiphytic, or rarely, lithophytic. You can grow most species in pots, in a standard bark mix, but some of the species with trailing stems, such as Angraecum doratophyllum, have to be mounted. It is even more important, in that case, to maintain the humidity. Species with climbing stems, such as A. infundibulare, need something like a stick or a moss pole in their pot so that they can scramble up it.
Other details of habitat are given in the descriptions with the speices. In fact, even though we cannot exactly duplicate all the conditions found in the natural habitat, there are enough other factors that we can improve upon in the green-house, such as ravages of insects and disease and destructive storms, that we feel justified in making the somewhat daring claim that there is really no reason why most of our angraecoids should not do just as well, if not better, in the greenhouse than in the wilds. But this claim can only be made if we have ourselves paid the price of informing ourselves of their basic requirements and have taken the pains to look for and find the best little niche for each.
Bibliography and References:
Arends JC, Van der Laan FM. 1986 Cytotaxonomy of the Vandeae. Lindleyana. 1. 33-41. Aerangis, Ancistrorhynchus, Angraecopsis, Angraecum, Calyptrochilum, Cyrtorchis, Diaphananthe, Eurychone, Jumellea, Microcoelia, Ossiculum, Podangis, Rangaeris, Sphyrarhynchus, Summerhayesia, Tridactyle.
Bosser J. 1987 Contribution a l'etude des Orchidaceae de Madagascar et des Mascareignes: 22. (Contribution to the study of the orchids of Madagascar and the Mascarenes: 22.) Bull. Mus. Nation. Hist. Nat., B, Adansonia 9. (3): 249-254 (1987)
Bosser J. 1988 Contribution a l'etude des Orchidaceae de Madagascar et des Mascareignes: 23. Bull. Mus. Nation. Hist. Nat., B, Adansonia 10. (1): 19-24 (1988)
Bosser J. 1989 Contribution a l'etude des Orchidaceae de Madagascar et des Mascareignes: 26. (Contribution to the study of the orchids of Madagascar and the Mascarenes: 26.) Bull. Mus. Nation. Hist. Nat., B, Adansonia 11. (4): 369-382 (1989)
Bosser J. 1989 Contribution a l'etude des Orchidaceae de Madagascar et des Mascareignes: 24.(Contribution to the study of the orchids of Madagascar and the Mascarenes: 24.) Bull. Mus. Nation. Hist. Nat., B, Adansonia 11. (1): 29-38 (1989)
Bosser J. 2007 Contribution a l'etude des Orchidaceae de Madagascar, des Comores et des Mascareignes. XXXVI. Description d'un Cynorkis nouveau de la Reunion et d'un Angraecum nouveau de Madagascar. Adansonia 29. (1): 13-17.
Cribb P, Pollard BJ. 2002 New orchid discoveries in western Cameroon. Kew Bull. 57. (3): 653-659 (2002)
Garay, L.A. (1973) Systematics of the genus Angraecum (Orchidaceae). Kew Bulletin, 28, 495-516.
Gasson P, Cribb PJ. 1986 the leaf anatomy of Ossiculum aurantiacum Cribb & van der Laan (Orchidaceae: Vandoideae). Kew Bull. 41. 827-32.
Hermans J, Cribb P. 1997 A new species of Angraecum (Orchidaceae) from Madagascar. Orchid Rev. 105. (1214): 108-111 (1997)
Hermans J, Cribb P. 2005 The Angraecum germinyanum complex. Orchid Rev. 113. 90-97
Hermans J, Cribb PJ, Bosser J. 2002 A distinctive new species of Angraecum from Madagascar. Orchid Rev. 110. (1243): 22-24 (2002)
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Hermans J. 2004 Plant portraits: 510. Angraecum praestans. Orchidaceae. Curtis's Bot. Mag. 21. (4): 248-250, plate 510. (2004)
Hermans, J. & Cribb, P.J. (2005). The Angraecum germinyanum complex. Orchid Review 113 (1262): 90-97.
Hermans, J., Cribb, P.J. & Bosser, J. (2002). A distinctive new species of Angraecum from Madagascar. Orchid Review 110 (1243): 22-24.
Hillerman F. 1981 Angraecum sororium and Madagascar revisited: part 1. Vanquished by the Vazimba. Amer. Orchid Soc. Bull. 50. (4): 388 - 392 (1981)
La Croix I. 1993 The genus Angraecum. Orchid Rev. 101. (1193): 252-256 (1993)
La Croix I. 1996 Angraecum bancoense and its relatives. Orchid Rev. 104. (1212): 325-328 (1996)
La Croix I. 2002 Plant portraits: 441. Angraecum compactum. Orchidaceae. Curtis's Bot. Mag. 19. (2): 92-96 (2002)
La Croix, I. 1996. Angraecum bancoense and its relatives. Orchid Rev. 104(1212): 325-328.
Leroux, A. (1979) Angraecum spectabile Summerth. . L'Orchidophile, 36, 1267.
Mann A. 1989 Angraecum sesquipedale, a Christmas tale. Florida Orchidist 32. (4): 198-201 (1989)
Peters H. 1997 Treasures in paradise. S. Afr. Orchid J. 28. (4): 135-139 (1997)
Stévart, T., Cawoy, V., Damen, T. & Droissart, V. Taxonomy of West Central African orchid (1): A new Angraecum sect. Pectinaria (Benth.) Schltr. (Orchidaceae) from Gabon and Equatorial Guinea. Systematic Botany.
Stewart J. 1987 Fine species at Westminster: Angraecum infundibulare. Orchid Rev. 95. (1130): 390-391 (1987)
Summerhayes V.S. 1937. Angraecum doratophyllum. Bull. Misc. Inf. Kew, 465.
Williamson G. 1996 A new species of Angraecum (Orchidaceae) from south central Africa. Kew Bull. 51. (3): 557-559 (1996)