Eurychone Schltr. in Beih. Bot. Centralb. 36: 134 (1918).
Epiphytic, monopodial, short-stemmed herbs. Leaves broadly oblong-elliptic, obovate or ligulate, unequally bilobed at the apex. Inflorescences pendent, 2-12-flowered, often shorter than the leaves. Flowers large, thintextured and more or less translucent, scented. Sepals and petals subsimilar, erect or spreading. Lip funnel-shaped, tapering into a wide-mouthed spur which is sharply constricted in the middle, then recurved and swollen at the apex. Column short and broad, lacking a foot; rostellum elongated, ligulate; anther cucullate, retuse; pollinia 2, ellipsoid; stipes 1, linear; viscidium 1, oblong or ovate, relatively large.
Type species:
Eurychone galeandrae (Reichb. f.) Schltr.
Neither species of Eurychone is common in cultivation and I surmise that this is both because they are relatively uncommon plants in the wild and because they can be rather temperamental when grown. I have grown and flowered both species in an intermediate greenhouse (minimum night temperature c. 15°C) but suspect that they might be better in a warm greenhouse (c. 18°C). Eurychone rothschildiana in particular, seems prone to what might be called 'sudden death syndrome', where a plant seems perfectly healthy one day, then suddenly drops all its leaves and is dead within a week.
Any orchid can behave in this unhelpful way - even in the wild, one may find the occasional dead plant in a colony of healthy ones - but most people I know who have grown Eurychone rothschildiana have experienced this at some time. Some unfavourable environmental factor must be responsible but it is not easy to work out what, possibly a cold draught.
Young plants of Eurychone galeandrae can be difficult to get established, but once they have developed a good root system, they seem to have a firmer grip on life. It has been suggested (Roberts, 1999) that Eurychone species are twig epiphytes and, as such, are naturally short-lived, but I am not convinced that this is the case.
As is shown in the habitat descriptions given in the accounts of the individual species, they do not consistently grow on twigs or small branches. Often if a twig or small branch breaks, any epiphytic orchids, which are often lightly attached, become caught up in undergrowth and continue to live successfully there.
Both species of Eurychone will grow in a pot in a free-draining epiphyte mix but, because the peduncle is so short and the lowest flowers of the raceme are borne close to the stem, plants look much better mounted on a raft or slab of bark. Humidity should be high but ventilation should be good, although cold draughts should be avoided. Eurychone rothschildiana seems to prefer to be heavily shaded, E. galeandrae rather less so. They are no more prone to pests and disease than any other orchid although slugs seem to have a tendency to home in on buds and newly opened flowers.
Both species have a further asset in that their flowers are fragrant; the scent of Eurychone. rothschildiana has been likened to that of lemon soap or lily-of-the-valley. It is worth taking trouble over the cultivation of these plants.
Vegetatively, the two species look quite different, Eurychone galeandrae has rather narrow, dull olive green leaves while those of Eurychone rothschildiana are broad with an undulate edge, dark green but not olive green. In fact, a sterile plant of this species looks very much like Aerangis kotschyana (Reichb.) Schltr.
Key to the genus Eurychone Schltr.
W. Trop. Africa to Uganda and Angola
Bibliography and References:
Arends JC, Van der Laan FM. 1986 Cytotaxonomy of the Vandeae. Lindleyana. 1. 33-41. Balkema, Rotterdam; Bechtel, P., Cribb, PJ. & Launert, E. (1992). Manual of Cultivated Orchid Species, ed. 3.Blandford Press, London; Carlsward BS, Stern WL, Bytebier B. 2006 Comparative vegetative anatomy and systematics of the angraecoids (Vandeae, Orchidaceae) with an emphasis on the leafless habit. Bot. J. Linn. Soc. 151. 165-218; Gasson P, Cribb PJ. 1986 the leaf anatomy of Ossiculum aurantiacum Cribb & van der Laan (Orchidaceae: Vandoideae). Kew Bull. 41. 827-32; Geerinck, D. (1992). Flore d'Afrique Centrale, Orchidaceae, part 2; Herndon CN. 1997 Eurychones of Africa. Orchids 66. (5): 490-493 (1997); La Croix I. 2001 The genus Eurychone. Orchidaceae. Curtis's Bot. Mag. 18. (3): 153-162 (2001); La Croix, I.F. & la Croix, E.A.S. (1997). African Orchids in the Wild and in Cultivation.orchids. 1986 translation, Australian Orchid Foundation; Piers, F. (1968). Orchids of East Africa, ed. 2. Cramer, Germany; Pottinger M. 1979 The mighty miniatures: five African beauties. Orchid Rev. 87. (1031): 170 - 173 (1979) - Illus., col.illus. Eurychone rothschildiana, Podangis dactyloceras, Bolusiella imbricata, Eggelingia ligulifolia, Mystacidium capense; Pottinger M. 1982 African orchids: Eulophiella and Eurychone. Orchid Rev. 90. (1067): 299-301 (1982)- illus. Eurychone rothschildiana. Geog=5 (KR, 198204812); Pottinger, M. (1983). African Orchids, a Personal View. HGH Publications, Wokingham; Reinikka, M.A. (1995). A History of the Orchid, ed. 2. Timber Press, Oregon; Roberts, K. (1999). Eurychone. African Orchid Alliance Magazine, Sept. 1999. Antwerp; Rolfe, R. (1898). Flora of Tropical Africa, vol. 7. London;Schlechter, R. (1918). Attempt at a natural new classification of the African angraecoid;Sheehan T, Sheehan M. 1993 Orchid genera illustrated: 153. Eurychone. Amer. Orchid Soc. Bull. 62. (7): 720-721 (1993); Stewart, J. & Bob Campbell (1970). Orchids of Tropical Africa. Allen, London; Summerhayes, V. S. (1968). Orchidaceae. In: Flora of West Tropical Africa, ed. 2, vol. 3, 1. London. Timber Press, Oregon: Wood jj. (1989). In: Cribb, PJ., Orchids of Tropical East Africa, Orchidaceae Part 3.