AFRICAN

ORCHIDS

Oeonia rosea Ridl., J. Linn. Soc., Bot. 21: 496 (1885).
Heterotypic Synonyms:
Oeonia oncidiiflora Kraenzl., Bot. Jahrb. Syst. 17: 56 (1893).
Oeonia forsythiana Kraenzl., Bot. Jahrb. Syst. 28: 171 (1900).
Description:
Plants with very long, pendent or climbing slightly branched stems, thin and with numerous leaves, very distant, oval-oblong or elliptical (22-45 x 10-26 mm) rounded-subcordate and embracing the stern basally inflorescences longer than the leaves, very loosely 3-7 flowered, flowers very large (25 mm in diameter), greenish or slightly yellowish, with the labellum white and maculate bright red in its throat. Sepals obovate-oblong (10 x 4 mm above the middle), obtuse and 3 veined. Petals similar to the sepals bin narrower (3 mm). Labellum 25-26 mm long, 4-lobed; inferior lobes rounded, wider than long (5 x 7 mm), median lobes widely flabellate-cuneiform and wider than tall (14-15 mm wide) apically, sometimes sinuate-notched on the internal margins, flat, diverging and each 7 veined; veins several times bifurcate; sprinkled basally with small hairs spur with its oriface wide (5 mm), attenuate from the oriface to the middle, then slightly dilate and obtuse apically, to all of 7 mm long. Column 2-3 mm tall, nearly as wide; auricles sub rectangular (2 x 1.2 mm), median tongue of the rostellum thick, cylindrical, slightly attenuate toward the apes. Papillous, and slightly shorter (1.8 mm) than auricles. Anther provided behind with a flattened, excised-bidentate apicule; pollina yellow, obpiriform, each with its own retracted cauda, inserted in small cupule, hyaline and situated in front of the 2 sub rectangular retinacles (1 x 0.4 mm) and well separated Pedicel 15 mm long.
Habitat:
Oeonia rosea grows epiphytically in tree branches in eastern and central Madagascar, on the plateau as well as on the well-watered eastern slopes, at altitudes of 600 to 1,500 meters. It is indigenous to Madagascar, where it flowers between September and January.
Cultivation:
This little gem has proved difficult to grow. Usually when a shipment of plants is received, they are in a bundle 2 feet long, and will obviously have been cut off at the base, so one knows little about the original size, and many of the "pieces" at the bottom are dead or dying. If left intact and "potted" loosely with sphagnum moss packed about the base, the plants seem to prosper. If "separated," they seem to go downhill—as if they cannot bear to be separated from their "brother" stems. If the roots are potted in bark, they immediately die, for they MUST be left aerial, and they seldom adhere to anything. The species can grow in brighter light but low light is safer until the plant is well established as the leaves bum easily. They do better with high humidity. Seedlings taken from the flask seem particularly difficult to maintain, and probably need to be grown strictly epiphytically. We have had limited success growing this species on slabs with frequent misting.
Notes:
The flowers of this species are quite different for an angraecoid, and they have a bright spot of red in the throat, a lip of almost citron yellow, and sepals and petals of bright green. This absolutely charming little species could be very popular if it were easier to grow. In the meantime, it stands as a challenge to those hobbyists who are determined to grow the difficult. Certainly the rewards are worth the effort.
Distribution:
Mascarenes to Madagascar
References:
AOS Bulletin Vol 48 No 4 1979; AOS Bulletin Vol 53 No 8 1984; Cultivated Angraecoid Orchids Of Madagascar Hillerman & Holst 1986; Flora of Madagascar Perrier 1981; AOS Bulletin Vol 66 No 10 1997; Angraecoid Orchids Stewart, Hermans, Campbell 2006; Orchids of Madagascar Hermans 2007; Field Guide to the Orchids of Madagascar Cribb & Herman 2009; WCSP (2017). 'World Checklist of Selected Plant Families. 09.03-2017; http://apps.kew.org/wcsp/
Images:
Click on each image to see a larger version.

Habitat/In situ Habitat/In situ Habitat/In situ
Oeonia rosea 01 Oeonia rosea 02 Oeonia rosea 03
Photograph ©Gilles Grunenwald. Image used with kind permission. Photograph ©Gilles Grunenwald. Image used with kind permission. Photograph ©Gilles Grunenwald. Image used with kind permission.

In culture In culture In culture In culture
oeonia rosea 01 oeonia rosea 02 oeonia rosea 03 oeonia rosea 04
Photograph ©Leo Klemm. Image used with kind permission. Photograph ©Leo Klemm. Image used with kind permission. Photograph ©Leo Klemm. Image used with kind permission. Photograph ©Leo Klemm. Image used with kind permission.