Euclea undulata is one of the most common small trees across the vast subtropical and central interior regions of southern Africa. It is a most variable species due to its adaptability to different climatic and habitat conditions.
Euclea undulata is a very sturdy, evergreen, dense and twiggy shrub to small tree reaching an approximate size of 7 m in height and very often with an equal width. The bushy and rounded appearance of the trees is due to the numerous branches that carry the closely packed leaves on stems that often reach ground level, giving an appearance of large dark green mounds or domes in the landscape. Several specimens commonly grow closely together, and in such cases they can form impenetrable thickets, as is often the case in their southern to coastal distribution range.
The leaves are opposite to subopposite or may be arranged in whorls of 3 or 4, mostly towards the ends of branchlets. Leaves are small, obovate to narrowly elliptical, 20–40 x 5–15 mm, stiff, leathery, dark green or blue-green above, paler below and sometimes rusty brown. The leaf apex is broadly tapering, or rounded to abruptly attenuate, base tapering, margin entire, finely rolled under, conspicuously wavy, or almost flat; petiole 1–3 mm long.
The bark is grey, scaly longitudinally fissured or cracked, particularly with age. The branchlets are twiggy, angular and densely leafy with short internodes
Flowers are small, whitish to cream, carried on unbranched 5- to 7-flowered spikes of up to 20 mm length, hairless but with rust-coloured stalked glands. The spikes are solitary in the leaf axils and are somewhat scented, appearing from December to May.
Fruits appear from February and are single-seeded rounded berries, 4–7 mm in diameter, thinly fleshy, reddish brown becoming dark when ripe, in short sprays less than 12 mm long. In adult plants flowers and fruits commonly occur simultaneously, resulting in prolonged presence of fruit or flowers or both for most of the year.
Euclea undulata is not endangered and occurs in abundance over a vast distribution range.
Distribution and habitat
Euclea undulata occurs in a variety of climates ranging from tropical, subtropical and semi-arid to arid, where rainfall occurs either in winter, summer or right through the year. The species is found widespread over southern Africa, especially in South Africa, Mozambique, Zimbabwe, Botswana and Namibia. It favours open rocky slopes, low hills with valleys, open mopane/acacia woodland, watercourses and areas with frequent or scattered termite mounds commonly referred to as heuweltjies' (little hills).
In South Africa these trees can be found almost throughout the country with the exception of the central interior associated with high altitude habitats. E. undulata is generally associated with rocky rather than deep sandy habitats. This fact, rather than the altitude, is probably the main reason why the species is absent in parts of the Kalahari with deep sand.
Derivation of name and historical aspects
In southern Africa the Ebony family or Ebenaceae is represented by two genera namely Euclea and Diospyros. . The genus name Euclea means to be of good report, or to be famous, from the Greek ‘eukleia', which is derived from ‘eu'- meaning good, and ‘kleios' meaning report. It is suspected that this perhaps refers to the good quality ebony-type wood of some Euclea species, particularly that of Euclea pseudebenus . The specific name undulata is very apt and refers to the undulated or wavy appearance of the leaf blades. The species sometimes closely resembles E. divinorum which, however, has larger leaves and fruits. The inflorescences in Euclea undulata are also unbranched and less dense.
Euclea undulata is undoubtedly pollinated by insects such as bees who visit the scented flowers in abundance. Ants and honeydew-producing scale have also been noticed on the trees but it is suspected that they interact with each other rather than with the flowers. Although not very palatable, the leaves are browsed by a number of wildlife species and the fruit are eaten by birds and other mammals who disperse the seeds over large areas quite successfully.
Uses and cultural aspects
Almost all parts of Euclea undulata are used by people or animals in one way or the other. It yields excellent firewood that produces long lasting coals.The leaves are useful as fodder for stock, antelope and small herbivorous mammals while the fruits are eaten by birds, antelope and humans although not very tasty. The hard brown heartwood is heavy and close-grained which make it durable and strong and a suitable species for making fencing posts. The bark contains suitable quantities of tannin and is used to ease headaches, while the roots provide a remedy for toothache and heart-related ailments. Alternatively the roots, when used as a powder, can be a drastic purgative. In the Western Cape leaf preparations are taken orally to treat diarrhoea and disorders of the stomach, and as a gargle to relieve throat ailments such as tonsillitis.
Growing Euclea undulata
Euclea undulata is a resprouter and in the wild recovers easily from grazing or other forms of physical damage. In cultivation the same holds true when specimens are cut or trimmed. However, since the species is a slow grower, it is not advisable to interfere with the natural shape of the plants. Plants should simply be left to occupy whichever space they have been provided with, and in this way will naturally mature in their own unique shape and character.
E. undulata is best grown from seeds which must be allowed to ripen completely after the fruits have blackened and have fallen to the ground. Seeds can be tested for viability using a simple floating test to see whether they are potentially fertile or not. Potentially fertile seeds (the ones that have sunk) are then soaked in hot water and left overnight and sowed into a sandy loam soil mixture which should not be fine-grained, otherwise this may encourage the formation of a crust and/or compaction. Best is to mix 1 part coarse river sand with 1 part fine-milled bark and 1 part decomposed compost or loam. The mixture is levelled in a seed tray and the seeds are pressed in and lightly covered with the same soil to about the size of the seeds. Sowing has been successful throughout the year but the best results are obtained from spring through to summer.Care must be taken not to transplant seedlings prematurely; therefore one must wait until seedlings have grown to at least 5–6 cm.
After plants have been hardened off for at least two seasons, they can be safely planted out in the garden in a sunny position. Young plants need to be protected from frost and should be watered generously during their initial years. Plants are very suitable for small drier gardens, especially in the Karoo and semidesert areas of South Africa. For the best effect at least three plants should be planted in a small group at least 6 m apart or closer, if a hedge effect is desired. Plants are most pleasing when combined with other drought-adapted or thicket species such as Acacia karoo, Carissa bispinosa, Ficus cordata, Searsia burchellii, Sideroxylon inerme or Pappea capensis. Other good companion shrubs and succulent species include Pteronia incana, Plumbago auriculata, Euryops linearis, Helichrysum petiolare, Pelargonium citronellum, P. crithmifolium, P. paniculatum, Aloe speciosa, A. microstigma, Ruschia caroli, R. maxima, Drosanthemum speciosum, D. micans, D. bicolor, Tylecodon paniculata and Cotyledon orbiculata.
References and further reading
- Coates Palgrave, M., 2002. Keith Coates Palgrave Trees of southern Africa , edn 3. Struik, Cape Town.
- Germishuizen, G. & Meyer, N.L. (eds) 2003. Plants of southern Africa: an annotated checklist. Strelitzia 14. National Botanical Institute, Pretoria.
- Jackson, W.P.U. 1990. Origins and meanings of South African plant genera. Ecolab, University of Cape Town.
- Mannheimer, C. & Curtis, B. 2009. Le Roux and Müller's Field Guide to the Trees and Shrubs of Namibia. Macmillan, Windhoek.
- Stearn, W.T. 2003. Stearn's dictionary of plant names for the gardener.Cassel, UK.
- Smith, C. A. 1966. Common names of South African plants, Memoirs of the Botanical Survey of South Africa No. 35.
Karoo Desert National Botanical Garden, Worcester