Satyrium coriifolium

Sw.

Family name
: Orchidaceae
Common names: Ewwa-trewwa, Goue-trewwa, Ouma-trewwa, Rooi-trewwa. (Afr..)

FlowersWith its brightly coloured yellow or orange-red flowers, Satyrium coriifolium is one of the most attractive terrestrial orchids of the Cape Floristic Region. It is also one of the few species in its genus that is suitable for cultivation.

Description
The plants are perennial and have large underground tubers which enable them to survive the dry summer. Stems are mostly 25 to 50 cm tall and are normally very robust. Satyrium coriifolium can readily be distinguished from all others in its genus by its stiff leathery, semi-erect leaves with orange-red bars near the sheathing bases.

The flower spike with its bright orange or yellow, comparatively large nodding flowers is very striking. As is typical in the genus Satyrium, the flowers are 'non-resupinate' (meaning that their hood-like lip faces up while the sepals and petals point down). The lip has generally two spurs in Satyrium, which is unique in orchids. The main flowering time of the species is from August through to November, depending on the available moisture in the habitat of the plants.

Conservation status
The species is locally common and has occasionally even become established as a roadside weed. However, due to its attractive flowers it is sometimes illegally collected which may account for its rarity in certain areas.

Distribution and habitat
Satyrium coriifoliumSatyrium coriifolium is found in the western and eastern parts of the Cape Floristic Region from Cape Town to Grahamstown, and northwards as far as Clanwilliam. Its most common habitat is moist, sandy flats below 300 m above sea level (rarely up to 750 m). Colonies are often extensive and may consist of hundreds of plants. Though not essential for flowering, fire appears to have a marked enhancing effect on the flowering as in many other Cape orchids.

Derivation of name and historical aspects
Olof Swartz, the famous Swedish botanist described Satyrium coriifolium in 1800, in the same publication in which he also provided the original description of the entire genus. He called the genus Satyrium which is derived from the Greek mythology, named after the two-horned satyr (half man and half goat). The name most likely refers to the two lip spurs of the genus. An alternative theory was presented by Hall (1982) who noted that the name possibly alludes to the goat-like smell of some of the species. Satyrium is a genus of about 84 deciduous terrestrial orchids in montane grassland and scrubland in sub-Saharan Africa. In addition, a few species are found in Madagascar and adjacent island, and three even range into Asia. As with the related genus Disa, the largest species number and the greatest structural diversity are found in the Western Cape, South Africa.

The epithet coriifolium refers to the stiff leaves of the species (from Latin corium, leather, and folium, leaf).

Ecology
It is hardly surprising that the bright flowers of this species attract sunbirds. The birds perch on the sturdy stems of the plants and feed on the nectar in their flowers. In the process, the pollinia (orchid pollen is normally united to form clumps termed 'pollinia') are attached to the bird's beaks. Bird species involved are mainly Malachite Sunbirds, but also occasional visits by Orange-breasted Sunbirds and Lesser Double-collared Sunbirds have been reported.

Although Satyrium coriifolium and the related species S. carneum and S. erectum usually occupy different habitats and have slightly different flowering times, occasional natural hybrids occur.

Uses and cultural aspects
Most southern African orchids have no major known economic uses, except for their horticultural potential and their use as traditional charms. There are no records indicating that S. coriifolium is used as a charm, but it does have great horticultural potential.

Growing in the wild

Growing Satyrium coriifolium

Satyrium species have a reputation of being difficult in cultivation and are therefore rarely found in collections, but they may be grown successfully if one adheres to certain rules. In fact, growing deciduous terrestrial orchids is sometimes considered an interesting challenge for the advanced grower. S. coriifolium is, due to its robust habit and attractive appearance, among the Satyrium species best suitable for cultivation. Given its fairly wide geographical distribution, across the winter-rainfall region, all-year rainfall region and summer-rainfall region, the species is less specific in its water requirements than many other species. More about Satyrium species and their cultivation can be found in the section on southern African orchids.

Satyrium coriifolium is best grown in large pots, rather than garden beds, to more easily control growing conditions.

As with all other South African orchids, this species is protected by law, and it is therefore highly illegal to dig up plants in the wild. Occasionally, plants are available in specialist nurseries or from botanical gardens.

One of the main requirements for successful cultivation of deciduous terrestrial orchids is an understanding of the natural habitat of the plants and the climatic conditions, and the associated natural rhythm of the plants. This relates for example to the main watering period in winter or early summer (depending on the rainfall region of your plant). In the resting period after flowering, the plants must be kept dry with only occasional light watering - plants are dormant at this time, i.e. their above-ground parts are dry (December to approx. May). Also the temperature regime requires a simulation of the natural conditions. Winter temperatures, from about June to September, should be cool (5-10°C), and those in summer from December to March high (20-30°C).

A good growing medium is 70% river sand and 30% milled bark or compost, and composed pine needles can also be used. If you have access to the soil in the natural habitat of the plant, it is always beneficial to add some of this original substrate as it contains the mycorrhizal fungi which enhance the growth of the orchid. A good drainage is always essential, and it is also vital that the growing medium is slightly acidic. Plants can be shaded to about 30 or 50%. Clean and slightly acidic water is essential for watering.

Propagation by seeds is very complicated in orchids and requires the facilities of a modern chemical laboratory. However, small-scale vegetative propagation can be attempted. Satyrium coriifolium belongs to the species that occasionally produce more than one replacement tuber, and clumps of plants can therefore be divided carefully.

Satyrium species are not normally prone to diseases, but occasional pests are aphids and red spider.

Although Satyrium in uncommon in cultivation at present, it is said that terrestrial orchids in general have great horticultural potential. Hybridisation attempts have been very limited, but S. 'Cape Amber' is an artificial hybrid of Satyrium coriifolium with S. acuminatum as the second parent.

References

  • Bolus, H. 1888. The orchids of the Cape Peninsula. Transactions of the South African Philosophical Society 5: 75-200.
  • Bolus, H. 1918. The orchids of the Cape Peninsula, 2nd ed. Cape Town : Darter Bros. & Co.
  • Golding, J. (ed.) 2002. Southern African plant red data list. SABONET Report 14. Pretoria
  • Hall, A.V. 1982. A revision of the southern African species of Satyrium. Contributions from the Bolus Herbarium 10: 1-142.
  • Johnson, S.D. 1996. Bird pollination in South African species of Satyrium (Orchidaceae). Plant Systematics and Evolution 203: 91-98.
  • la Croix, I.F. & la Croix, E. 1997. African orchids in the wild and in cultivation. Portland, Oregon, Timber Press.
  • Linder, H.P. & Kurzweil, H. 1999. Orchids of southern Africa. Rotterdam : Balkema.
  • Schelpe, E.A. 1966. An introduction to the South African orchids. Cape Town and Johannesburg : Purnell & Sons.
  • Stewart, J., Linder, H.P., Schelpe, E.A. & Hall, A.V. 1982. Wild orchids of southern Africa. Johannesburg : Macmillan South Africa.
  • Wodrich, K. 1997. Growing South African indigenous orchids. Rotterdam : A.A. Balkema.

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Author
H Kurzweil

Compton Herbarium, Kirstenbosch Research Centre
August 2005

 

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