This Tree is up to 15m high. The margins of the large simple Leaves have spines. Dioecious, yellow or greenish Flowers that lack petals develop directly on the trunk and branches. Fruit is a wrinkled berry.
Drypetes natalensis, Cyclostemon natalensis.
RSA Tree No. 329.3.
Common names: Natal Ironplum, Stem-fruit Ironplum;, Natal drypetes, Stem-fruit drypetes.
Family: Putranjivaceae (was Euphorbiaceae) has 3 distinct genera containing at least 210 species. The local genera are: Sibangae, Putranjiva and Drypetes. Leaves are coriaceous and 2-ranked. Young leaves are peppery due to sulphur containing chemicals. The usually small unisexual Flowers are in a condensed or in a close cluster arrangement. Fruit is a 1 seeded drupe ending in 2-3 persistent stigmas. Members of this family produce mustard oils and Brassicaceae is the only other family that does so.
Name derivation: Drypetes – ready to fall from the sky – referring to the ripe fruit. natalensis – from KwaZulu-Natal (formally Natal). There are 5 species of the genus Drypetes in southern Africa.
Conservation Status: L C. (Least Concern). Assessed 2009 (Raimondo et al.).
This small to medium Tree reaches up to 10m and occasionally 15m high. The Stem (main axis of the plant, the leaf and flower bearing as distinguished from the root bearing axis) is either multi-stemmed or single and up to 30cm wide. It is irregularly fluted (grooved, funnelled, channelled). The Bark has ridges on which many flowers and fruit are borne. Otherwise, it is smooth and grey. Young branches are angular and pubescent (with dense fine, short, soft hairs, downy) initially but becoming glabrous (hairless) with age. In a mature tree, the remaining branches start above 4m. From here, they spread forming a dense rounded crown.
On this evergreen tree the alternate, elliptic to oblong or broadly lanceolate Leaves are large – up to 21 x 8,5cm. The leaves are contained in the same plane. The Blade is stiff and leathery. It is dark green and shiny above and light green and less shiny below – where the venation is much more clearly visible and where the yellowish midrib protrudes. The Blade usually has 7-10 pairs lateral veins that loop and loop again before reaching the margin. The Margin is stiff and has widely spaced sharp spine tipped teeth. These teeth may occasionally be almost absent. The midrib and secondary veins are dull yellow and raised below. The Apex may be rounded or may taper – even forming a drip-tip. The Base is asymmetric. The relatively thick and strong Petiole (leaf stalk) is up to 9mm long and is only initially pubescent. Stipules (basal appendages of the petiole) are linear and small – up to 4mm long. They are easily detached and fall early. Glands are absent.
The trees are dioecious (having male and female flowers on separate plants). The Flowers are in fascicles (here conspicuous dense clusters of up to 100 flowers growing together) on larger branches – old wood – and on the main trunk – similar to stamvrug (Englerophytum magalismontanum). Against the dark trunk background, the yellowish flowers are quite distinctive. Flowers may have an unpleasant odour. The Calyx has 5-6 overlapping Sepals – each of which is deeply concave, yellow or greenish white and up to 4 x 3,5mm. Petals are absent. In the Male flowers, there are 11 or 12 Stamens with free filaments. They occur in 2 whorls. The ovary is usually absent. In the Female flowers, the Ovary has up to 4 locules which each contain 2 Ovules. The Styles are short and each Stigma is thick and flattened. (Sep-Oct).
The Fruit is slightly 2 to 3-lobed (usually 3) or almost spherical. It is a stalk-less Berry (a pulpy, indehiscent fruit like a grape or tomato), which is up to 3cm wide As it matures the colour changes from green to yellow or orange. The berries are usually wrinkled. The pericarp (wall of fruit) is slightly fleshy and, on drying, becomes hardened. Seeds are solitary by abortion. They are ovoid and orange. (Dec-Mar).
Distribution & Ecology
These trees are located in KwaZulu-Natal, Eastern and southern Africa: Zimbabwe, Mozambique, Sudan, Somalia, Kenya, Tanzania and Malawi. They are found in the understory of dry evergreen dune and riverine forest; often in rocky places; semi-deciduous forest and at elevations ranging from sea level to 1 500m. Monkeys eat the fruit. These trees are not common in wetter forests.
For fruit or seeds, both male and female plants need to be grown. The Tree is good for shade. The Fruit is edible. The Wood is used to make kitchen utensils, sticks, tool handles building material, beds and fuel – including charcoal.
Boon, R. 2010. Pooley’s Trees of eastern South Africa. Flora and Fauna Publications Trust, Durban.
Coates Palgrave, M. 2002. Keith Coates Palgrave Trees of Southern Africa, edn 3. Struik, Cape Town.
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.
van Wyk, B. & van Wyk, P. 1997 Field guide to Trees of Southern Africa, Struik, Cape Town.