Cyrtorchis Schltr., Orchideen: 596 (1914).
Homocolleticon (Summerh.) Szlach. & Olszewski, in Fl. Cameroun 36: 727 (2001).
Epiphytic herbs, sometimes saxicolous. Stem, elongated, sometimes much branched, covered below with the sheaths of the fallen leaves closely leafy at the apex, giving off aerial roots at intervals. Leave, distichous, often imbricate, generally spreading or recurved, oblong, ligulate or linear, usually fleshy or leathery and sometimes very thick, often V-shaped in section. Inflorescences arising from the axils of the leaves or fallen off leaves, usually solitary, spreading or more or les recurved, simply racemose, few-to many-flowered. Flowers alternate, rather large, white or cream-coloured, often turning yellow or orange with age, the spur sometimes greenish, usually very fragrant; bracts relatively large and conspicuous, brownish. Sepals and petals free, lanceolate, very acute, the lateral sepals and petals oblique, all usually strongly recurved. Labellum similar to the petals but with a rather broader base, markedly recurved, passing gradually at the base into i long tapering spur. Column short and thick, without a foot; androcilnium only slightly excavated, and gently sloping towards the front; anther cucullate, usually drawn out into a distinct beak in front; pollinia 2, globose or ellipsoid, each attached to a more or less spathulate stipes which is narrowed at the base; viscidium one, oblong or ligulate, either uniform in structure and thin in texture, or with an indurate saddle-shaped upper part and a very thin hyaline lower part; rostellum long, beak-like, projecting forwards, bifid on removal of the pollinarium, usually with a short central tooth; stigmatic cavity transversely oblong or nearly orbicular.
C. arcuata (Lindl.) Schltr.
Rudolf Schlechter created the genus Cyrtorchis to accommodate a small group of species allied to Angraecum arcuatum Lindley (syn. Listrostachys arcuata (Lindley) Reichenbach f.). They all have lanceolate, recurved sepals and petals and a very similar hp that passes gradually into a long, curving and tapering spur. The generic name refers to these features, from the Greek kyrtos, a swelling or curve, and orchis, orchid.
Although he only named 4 species of Cyrtorchis when he created the genus in 1914, Schlechter stated that the genus contained about 15 species altogether. Nearly 40 taxa have been described since then and about 15 species are now recognised.
The genus was revised in 196o by V.s. Summerhays,who divided it into two sections depending on the character of the viscidium. This difference is of no relevance to the orchid grower, as both sections are similar in other ways. Few species are common in cultivation, but any is worth to growing, if it can be obtained.
The two section is:
Cyrtorchis section Cyrtorchis
Viscidium consisting of an upper indurate saddle-shaped portion and a lower thin hyaline portion. Lateral lobes of rostellum widened just above the very narrow base. Stipites often much widened in the apical half.
Cyrtorchis section Homocolleticon.
Viscidium almost uniform in texture, thin and more or les hyaline. Lateral lobes of rostellum almost parallel-sided in basal part, not at all widened. Stipites usually only moderately widened in the apical half.
Cyrtorchis species can be found in almost every country in tropical Africa, and it has to be admitted that knowing where a plant comes from is often a great help in trying to identify it. The type species, C. arcuata, was originally described by John Lindley in 1836 from material collected in south-eastern Africa by the German collector J. F. Drège (1794—1881), but is now known to be one of the most widespread African epiphytic orchids, from Sierra Leone to Kenya and from Ethiopia to the Eastern Cape in South Africa.
These plants grow as epiphytes or lithophytes in the wild and are easily maintained in cultivation. They thrive in a pot or basket of free-draining compost such as bark. Most of these plants produce small branches from the lower part of the stern after some of the leaves have fallen, so that specimen plants are produced in a relatively short time. Attention must be paid to growing and resting seasons, since the plants do not need much water or nutrient when they are dormant. Smaller plants of all the species are also established easily on pieces of bark and grow well when mounted in this way.
The star-shaped, white or cream-coloured flowers that sometimes fade to yellow or orange as they age are characteristic. They make Cyrtorchis species amongst the easiest African epiphytic orchids to place in a genus, but they are some of the most difficult to identify individually. The rather stiff plants with leaves in 2 rows on either side of the stern are also characteristic of most species.
Another feature is the large pale bracts that loosely enclose the flowers in bud and turn black or dark brown or are shed by the time the flowers have opened. All the flowers are sweetly scented, particularly in the evening.
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