Eulophia welwitschii
Introduction
This attractive orchid makes a striking display in summer with its bright yellow inflorescence, especially when occurring in dense stands. It is often seen in marshy areas and seasonally inundated grasslands, but sadly, due to human activities, this species is less commonly seen in urban areas.
Description
Description
Eulophia welwitschii is a perennial, terrestrial orchid, about 800 mm high, with underground corms, and stiffly erect leaves which are present at flowering time. The leaves are strongly pleated. The flowers are borne on a single, tall flowering stem in a dense head of up to 25 flowers. Both the petals and sepals are yellow (pale green or cream-coloured in some cases) with the sepals and petals held close together. It has dark red-purple markings on the inside of the side lobes and base of the lip and thread-like crest papillae. The spur is slender and short and hidden by the bracts. It flowers from November to January, coinciding with the summer rains. After flowering, the plants produce one or more seed capsules on the flower spike. When they are dry and grey-brown, they burst open to release thousands of seeds which are very small, almost dust-like, and are dispersed by wind.
Conservation Status
Status
Eulophia welwitschii is not listed as a threatened plant in the Red Data List, but due to the increasing destruction of its habitat, the natural urban populations might well soon be at risk. Especially in the metropolitan areas of Gauteng, the grasslands are under extreme pressure of development.
Another serious threat to the plants is the pink Argentinian weed, Campunoclinium macrocephalus (pompom weed) which is an aggressive invader of grassland.
In the early 1990s a small portion of land adjacent to the development of the Persequor Technopark in Pretoria was set aside to afford protection to this orchid. Unfortunately, this land is now severely invaded by pompom weed and a special effort is required to eradicate it and ensure the survival of the orchid in this area.
In South Africa all orchids are protected by law. It is illegal to take orchids from the wild, and permits need to be obtained to remove plants.
Distribution and habitat
Distribution description
Eulophia welwitschii grows well dispersed in dry or seasonally flooded grassland and marshes, often in large populations. The species occurs throughout the eastern parts of South Africa (Eastern Cape, KwaZulu-Natal, Mpumalanga, Gauteng and Limpopo) and Swaziland and is also widespread in tropical Africa. It grows from sea level up to high altitudes.
Derivation of name and historical aspects
History
Eulophia refers to the comb-like appendages on the lip and is derived from the Greek words Eu, meaning good, and lophos, meaning a comb or crest. The species name is in honour of F. Welwitsch, an Austrian botanist, who is also remembered as the discoverer of the desert plant Welwitschia mirabilis.
The genus Eulophia consists of about 250 species occurring in the tropics and subtropics, with 42 species found in the southern African subregion. There is confusion as to whether this species occurring in tropical Africa is E. welwitschii, and in some cases these populations are referred to as E. zeyheri. However, Klopper et al. (2006) list both the southern African and tropical forms as E. welwitschii.
Ecology
Ecology
Very little is known about the ecology of Eulophia species. As with all orchids, they are specially adapted to their pollinators, which often are a few insect species.
A great deal of research has been done on the germination of orchid seeds. The embryo grows in symbiosis with threads of a fungal mycelium, which the orchid keeps in control by producing fungicides. E. welwitschii is fire-tolerant, being dormant during the fire season in the grassland, but whether it requires fire to flower is not known.
Uses
Use
There is not much known on the medicinal and cultural uses of orchid species. They are not known to be poisonous. Some species of Eulophia are used medicinally, but there is no literature that points to E. welwitschii being used in any treatment. Orchids from other genera (Disa, Satyrium, Habenaria and Brachycorythis) are used in Zambia and Malawi for making a product called chikanda or 'African polony' from the edible tubers, but since Eulophia species have rather fibrous tubers, it is unlikely that they are used for the same purpose.
Orchids are most sought-after in the horticultural industry, and the South African orchids have taken their rightful place next to their exotic counterparts in the collections of serious orchid growers.
Growing Eulophia welwitschii
Grow
Eulophia welwitschii has similar requirements to the more commonly cultivated species, E. speciosa. Members of orchid societies have started experimenting with E. welwitschi, but have not found it to be as easy-growing as other indigenous orchids. When suitable conditions are met, however, and they are not disturbed too much, they will flower rewardingly.
The best showcase for E. welwitschii in any garden is in a marshy wetland area, in combination with grasses, sedges and other flowering grassland species such as Chironia and Helichrysum. It prefers full sun in a moist position, but does not like to have its roots submerged in water for long periods. The best is to let it grow undisturbed in the garden. For new developments in grassland areas, especially if there are moist depressions, it is advisable to leave as much as possible of the original grassland untouched, and one will be surprised at what appears in the summer!
Plants can also be grown in pots, but they are more difficult to grow in cultivation than in a garden. In the growing season, be careful to water the plants regularly and do not allow them to dry out completely. Eulophia welwitschii is relatively frost tolerant, since they occur naturally in areas with moderate to strong frost. Potted plants should be sheltered during winter.
In winter, between April to August, the plants die back, with no leaves visible above the ground. Keep the plants dry during this dormant period. Over-watering can result in rotting. Start watering only when the new leaves appear in spring and stop watering as soon as the leaves turn yellow in autumn.
This species does not like too much disturbance and re-potting. If necessary, divide and transplant the plants in the dormant period. Use a mixture of leaf mould, bark, river sand and garden compost. Always keep a good portion of the original soil on the plants, as this contains the micorrhizal fungi required by the plants.
Feed the plants only in the growing season with diluted liquid fertilizer. Alternatively add compost or decaying organic matter when re-potting, which will provide the nutrients.
Propagate Eulophia welwitschii by means of division of the corms of old plants. Propagation by seed is rather difficult and requires advanced experience. This is because germination and seedling survival is dependent on symbiotic fungi and the exact conditions suitable for the survival of the fungus are not easy to maintain and require extra care.
Pests on Eulophia welwitschii are the same as for other orchid species. Aphids, red spider mite and thrips can be a problem. Instead of using chemical pesticides, spray or paint the plant with a mixture of one litre of water, one teaspoon of dish-washing liquid and one teaspoon of methylated spirits. In this way, one is not only gentle on the plants, but also on the all the other non-harmful insects that share one's garden. It is, however, not a long-term treatment, and should be re-applied as needed.
The genus Eulophia has enormous hybridizing potential, and some hybrids have been registered. Care should be taken that the hybrids do not escape or are not planted in natural areas, since these would compromise the genetic purity of wild populations.
References
- Bingham, M.G. & Kokwe, G.M. 2001. Where have all the flowers gone? SABONET News 6: 40.
- Brynard, A.M. 2003. Eulophia welwitschii. A safe haven for a rare orchid in the heart of Pretoria. Veld & Flora 89: 68, 69.
- Germishuizen, G. & Meyer, N.L. (eds). 2003. Plants of southern Africa : an annotated checklist. Strelitzia 14. National Botanical Institute, Pretoria.
- Golding, J.S. (ed.) 2002. Southern African Plant Red Data Lists. Southern African Botanical Diversity Network Report No. 14. SABONET, Pretoria.
- Klopper, R.R., Chatelain, C., Banninger, V., Habashi, C., Steyn, H.M., De Wet, C., Arnold, T.H.., Gautier, L., Smith, G.F. & Spichiger, R. 2006. Checklist of the flowering plants of Sub-Saharan Africa. An index of accepted names and synonyms. Southern African Botanical Diversity Network Report No. 42. SABONET, Pretoria.
- Linder, H.P. & Kurzweil, H. 1999. Orchids of southern Africa. Balkema, Rotterdam.
- Mayr, H. 1998. Orchid names and their meanings. Gantner Verlag, Germany.
- Van Wyk, Braam (A.E.) & Malan, S. 1998. Field guide to the wild flowers of the Highveld. Struik, Cape Town.
- Venter, H. 2006. Growing orchids in South Africa --a gardener's guide. Briza Publications, Pretoria.
- Watt, J.M. & Breyer-Brandwijk, M.G. 1962. The medicinal and poisonous plants of southern and eastern Africa, edn 2. Livingstone, London.
- Williamson, G. 1977. The orchids of south central Africa. Dent, London.
- Woodrich, K. 1997. Growing South African indigenous orchids. Balkema, Rotterdam.
Credits
Beate Hölscher
National Herbarium, Pretoria
January 2009
Plant Attributes:
Plant Type: Orchid
SA Distribution: Eastern Cape, Gauteng, KwaZulu-Natal, Limpopo, Mpumalanga
Soil type: Loam
Flowering season: Early Summer, Late Summer
PH: Acid
Flower colour: Brown, Cream, Yellow
Aspect: Full Sun
Gardening skill: Challenging
Special Features:
Good potplant
Wet sites
Horticultural zones
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