Plant may reach 3,6m high with a swollen and succulent stem + a grey-green bark. The slightly fleshy Leaves are simple. Showy, bisexual, 5-merous Flowers have white lobes surrounded by red. Fruit is a follicle.
Adenium multiflorum, Adenium obesum, Adenium obesum var. multiflorum.
RSA Tree No. 647.3.
Common names: Impala-lily, Impalalelie, Sabi Star.
Family: Apocynaceae (Oleander or impala lily (Adenium multiflorum) family). This family includes the exotic genera Oleander and Plumeria (Frangipani). Indigenous genera containing trees include Acokanthera, Adenium, Carissa, Rauvolfia and Tabernaemontana. Currently the family has 366 genera and in excess of 5 000 species. In RSA, there are 90 genera and about 700 species. All have milky or clear sap. The simple, entire and pinnately veined Leaves are usually opposite and may have stipules situated between the petiole and the stem. Inflorescence is usually a cyme (a broad, more or less flat-topped, determinate flower cluster, with central flowers opening first). The regular and bisexual Flowers are usually bracteate. The Calyx has 4-5, usually free sepals and the 4-5 Petals are joined – at least at the base of the staminal column. A corona (an extension) is often present either on the corolla, or on arising from the base of the staminal column. The 4-5 Stamens are variously located and have anthers with 2 pollen sacs. The superior to half-inferior Ovary has 2 carpels. Fruit is various. The often-compressed Seeds may have a tuft of silky hair at the micropylar (a small opening in the surface of an ovule, through which the pollen tube penetrates, often visible as a small pore in the ripe seed. During germination, the seedling’s radicle – embryonic root – emerges through the micropyle) end.
Name derivation: Adenium is either named after the district in South Yemen OR fat – referring to the succulent stems. multiflorum – many flowers. Other species of Adenium are located in southern Africa. They include A. oleifolium and A. swazicum.
Conservation Status: L C. (Least Concern). 2009 (Raimondo et al.). This plant is common in the Kruger Park and thus protected. Beyond our borders, it is on the Red Data list.
The thickset and spineless Tree is up to 3,6+m high but it is usually a shrub up to 1,5m. Here the Stem (main axis of the plant) is thick, swollen and succulent (have some parts that are more than normally thickened). There may be more than one stem arising from a tuber (swollen underground stem, which is a storage and regenerative organ, which help survival during dry winter months). The smooth Bark is grey-green and may be slightly pink. It can exude a white, watery sap. Some branches are almost vertical. All are smooth, thick, greyish white or slightly red.
On this deciduous plant, the Leaves occur at the ends of branches. They are simple (have a single blade which may have incisions that are not deep enough to divide the blade into leaflets) and are spirally arranged. The smooth leaves are obovate (the reverse of ovate, the terminal half is broader than the basal) to oblong and up to 12 x 8cm. The hairless leaves are slightly fleshy, especially when young. The Blade is glossy green to bluish green above and paler green and dull below. The midrib is often pinkish and is prominent on both surfaces. There are 6-11 pairs of lateral veins, which are more visible above than below. Conspicuous axillary glands are present – several in each axil. The Apex is rounded or notched. The wavy Margin is entire (with a continuous margin, not in any way indented but may be hairy). The Base tapers and is decurrent (leaf blades that partly wrap or have wings around the stem or petiole). The Petiole (leaf stalk) may be absent, obscured by a decurrent leaf or it may be up to 0,5cm long. Stipules (basal appendage of the petiole) are minute or absent.
The very impressive, almost hairless Flowers emerge in winter – usually before the leaves appear. Each is bisexual and actinomorphic (regular, symmetrical. Perianth, the calyx and corolla, are divisible into 3 or more identical sectors). The flowers are up to 5cm in diameter. Flowers occur in few-flowered terminal heads, or cymes (a broad, more or less flat-topped, determinate flower cluster, with central flowers opening first). The Calyx has 5 Sepals which are divided almost to the base. The Corolla tube is funnel-shaped and white – streaked with red or pink and hairy near the funnel opening. The 5 petal lobes are broad, spreading horizontally from the tube and have a crinkled margin. They are white to pale pink with red or rose pink tinged wide margins. Each lobe is as long as the tube, up to 4cm wide and lanceolate. Lobes overlap to the right. Occasionally all white flowers appear. The 4 Stamens are attached to the widened part of the corolla tube. Filaments are very short. The 4-locular lanceolate Anthers are fused with the stigma and end with a long, hairy appendage. There is a single Pistil (a unit of the Gynoecium, the female element of the flower, composed of the Ovary, Style and Stigma) containing a superior, hairless Ovary with many ovules and 2 free Carpels. The single short cylindrical Style has a capitate (formed like a head) Stigma possessing a basal rim. (May-Sep).
Fruit is a paired Follicle (dry dehiscent fruit, which is almost cylindrical and pod-like that opens only on the front side and is the product of the single pistil). It is up to 21 x 2cm but usually smaller, and covered with dense pinkish grey short soft hairs when young. The follicles taper at each end and are at right angles to the supporting stem. When mature the follicles are light brown and split to release the many seeds. Seeds are long and narrow, brown, grooved with some silky golden-brown hairs at the tips of both ends. These hairs aid the wind dispersal of seeds. (Jul-Jan).
Distribution & Ecology
These Plants are located in NE KwaZulu-Natal, Mpumalanga e.g. Shingwedzi in the Kruger Park, Limpopo Province, Botswana, Swaziland, Mozambique, Zambia, Malawi and into Tropical Africa. Grazing usually prevents the plants from growing very high. Consumers include Impala, Kudu and Rhino. Baboons uproot whole plants to feed on the tuberous rootstocks. Plants are common at low altitudes on rocky ridges and brackish flats. They are Found in sandy soil, in dry woodland, open grassland or in sandy woodland.
The plants may have toxic properties (fish and arrow poison) but are browsed by game. The milky Latex contains a toxic alkaloid which is a Cardiac glycoside that affects heart functioning. Seeds germinates easily but must not be over-watered. They should be grown in a frost-free environment. In warm, dry positions, they make a good container plant.
Boon, R. 2010. Pooley’s Trees of eastern South Africa. Flora and Fauna Publications Trust, Durban. p494.
Coates Palgrave, M. 2002. Keith Coates Palgrave Trees of Southern Africa, edn 3. Struik, Cape Town. p959.
Lawrence, G. H. M, 1951. Taxonomy of Vascular Plants, The Macmillan Company, New York. Tenth Printing 1965.
Palmer, E. & Pitman, N. 1972. Trees of southern Africa, Balkema, Amsterdam, Cape Town. p1923.
Schmidt, S. Lotter, M. & McCleland, W. 2002. Trees and Shrubs of Mpumalanga and the Kruger National Park. p556
van Wyk, B. & van Wyk, P. 1997 Field guide to Trees of Southern Africa, Struik, Cape Town. p34.