EULOPHIA HORSFALLlj

by Graham Duncan, Kirstenbosch

II /L

16 Veld &' Flora March 2000 AT KIRSTENBOSCH

The orchid Eulophia bout ten years ago, a single flowered in widely separated parts consists of about 200 species of Eulophia horsfallii of the Kirsten-bosch estate, such which are very widely A was donated to Kirsten­ as at the Gold Fields Educational Centre, and at the Harry Molteno distributed in , and also bosch from the Constantia, Cape Library, as well as just outside occur in Central America, Town garden of Miss Selma Bock, a most enthusiastic and successful Kirstenbosch in the grounds of the and South-East . grower of all manner of garden Church of the Good Shepherd The genus is particularly well . Miss Bock, who had an eye near the main entrance to represented in South Africa for the bizarre and the beautiful, Kirstenbosch. where its distribution is received her original plant from The major reason that most centred in the Eastern Cape, an employee of the local orchids cannot be raised success­ KwaZulu-Natal, Mpumalanga Constantia Catholic Church, but fully from seed sown under non­ and the Northern Province. no further details regarding its sterile conditions (as one would While many eulophias are origin are known. I carefully normally sow a tray of Lachenalia endemic to this country, the cultivated it in a large plastic pot seeds, for example) is that the distribution range of several in the Kirstenbosch bulb nursery seedlings of most of them are dependent for survival on a species found here extends and after two years the first inflo­ symbiotic association with a into Central and West Africa. rescence appeared, which rapidly grew to 2.3 m in height and specific fungus. The fungus Eulophia horsfallii is such an flowered for many weeks. The penetrates the roots of the orchid example and it is a most plant multiplied and flowered seedling and through the spectacular, large-flowered consistently every year in early exchange of nutrients, nutritional evergreen plant that grows in summer, and has often been benefit is obtained by the the dappled shade of swamp displayed in the bulb house in the seedling, and in some cases, by forest margins in KwaZulu­ Botanical Society Conservatory. the fungus as well. It is especially Natal, eastern Mpumalanga Although a few seed capsules during seed germination and and the Northern Province. formed quite readily qrrd subsequent growth of the seedling Its range extends much further produced large quantities of that the orchid's dependence on north as far as southern Sudan, typically'hne, dust-like seed, I its associated fungus is greatest. In addition, further requirements for west to Angola, Congo and paid little attention to these as the germination of viable seeds such along the coastal parts of West plants were growing extremely rp.~lfltiplying as sufficient moisture, favourable Africa. The species honours well,.and rapidly. S'ome years later, I noticed temperature and light levels also Mr J.B. Horsfall, a British several clumps of very healthy­ have to be present. The tiny dust­ horticulturist who flowered the looking plants with broad, pleated like seeds of orchids are very well type material collected in West leaves growing in three different adapted for wind dispersal, and Africa in his glasshouse in locations in between the partially this undoubtedly accounted for England, and which was buried retaining logs which form the appearance of plants of beautifully illustrated in the terraces in the Camphor E. horsfallii in the Camphor Curtis's Botanical Magazine Avenue at Kirstenbosch. At a Avenue, as well as those which in 1865. distance, the leaves looked similar appeared relatively long distances to those of Wachendorfia away from the bulb nursery. thyrsiflora, but closer inspection It is remarkable that optimum of the leaves and rootstock conditions of specific fungus, revealed that they belonged to an (present in the soil or on the bark orchid. The clumps continued to of retaining logs) as well as flourish in dappled shade and moisture, temperature and light poorly drained soil, and remained conditions prevailed at the evergreen throughout the winter locations where the seed of months. Finally one of the largest E. horsfallii landed, and success­ Claire Linder Smith's accompanying water-colour ofEulophia horsfallii was plants sent up a strong inflores­ fully germinated. Similarly, painted in 1986 from a specimen found cence in midsummer which volunteer seedlings of both growing near Kampala in southern proved to be E. horsfallii. Since Bonatea speciosa and Eulophia Uganda, while she was accompanying her husband, Peter Linder on a then, several other clumps of this petersii have also appeared in trans-Africa trip. species have appeared and various parts of the bulb nursery.

Veld &' Flora March 2000 17 GROWING EULOPHIAS

Eulophias are probably the most branches can be separated, Africa, but once our stocks at easily cultivated of all the ensuring that each branch is Kirstenbosch have increased geophytic southern African removed with a growing point. sufficiently, material will become orchids, and they are generally Separated branches must be available via the Kirstenbosch most suitably grown in shallow replanted immediately and kept Garden Centre and the Botanical containers in a very well drained well watered, and will require a Society's annual Garden Fair. @ medium such as equal parts of year or two of good growth before coarse river-sand, milled bark and well-rotted compost. The evergreen species are usually easier to grow than the ones, and evergreens like E. horsfallii, E. streptopetala, E. speciosa and E. petersii can also be successfully grown in gardens under optimum conditions. At Kirstenbosch, E. horsfallii has proved to be a most useful subject for slightly acid, poorly drained loam in dappled shade. It can also be grown in pots, but due to its robust nature, containers need to be deep (a 35 cm diameter plastic pot is ideal) in order to accommodate its vigorous root system. Regular heavy waterings are required every few days during the summer months. The plants remain evergreen when grown in dappled shade, but undergo a very short dormant period in mid-winter when grown in sunny situations. New leaf shoots form in early spring, and flowerbuds may appear at any time during spring and summer. The plants require plenty of organic matter incorporated into the growing medium, and when grown in containers, they benefit greatly from regular applications Eulophia horsjallii flowering near the Harry Molteno Library at Kirstenbosch. Photo: G.D. Duncan. of seaweed-based liquid fertilizer during summer. Heavy winter rainfall appears to have no ill flowering commences again. Further reading effect on the plants. As with all the other Eulophia Duncan, G.D. 1989. Eulophia. In: Du Plessis, N.M. and G.D. Duncan, Division of E. horsfallii clumps species with pleated leaves, the Bulbous plants of southern Africa: (as well as of all other Eulophia foliage of E. horsfallii is very 172-174. Tafelberg, Cape Town. species) is currently the only susceptible to attack by red spider Hall, A.V. 1965. Studies of the South African species of Eulophia. Journal of feasible method of propagation for mite during the hot summer South African Botany, supplementary the home gardener. Thick clumps months, and aphids can also vol. 5: 153-157. National Botanic Gadens are best divided in early spring, severely damage the developing of South Africa, Cape Town. Linder, H.P. and H. Kurzweil, 1999. just before the new leaf shoots flowerbuds. Both these pests can Orchids of Southern Africa. Balkema, begin to develop. The rhizomatous be controlled with Bio Kill Garden Rotterdam. rootstock of E. horsfallii consists Spray. To date, no fungal diseases Pooley, K, 1998. A field guide to wildflowers KwaZulu-Natal and the of persistent pseudobulbs which have been noted on E. horsfallii at Eastern Region: 372-373. Natal Flora are usually entirely subterranean, Kirstenbosch. Publications Trust, Durban. and linked by short cylindrical As far as I know, propagative stems. The rootstock forms material of E. horsfallii is not branches with age, and these available anywhere in South

18 Veld & Flora March 2000