Dioecious, spineless Tree may reach 30m+. Watery sap is present. Simple Leaves. Base 3-veined Deciduous. Small wind pollinated Flowers are regular and lack petals. Fruit: red, fleshy drupe. Seeds small.
Celtis mildbraedii, Celtis franksiae, Celtis usambarensis, Celtis soyauxii.
Common names: Natal White Stinkwood, Red-fruited White-stinkwood, Natal Elm.
Family: Cannabaceae (white stinkwood family). The family includes approximately 11 genera including Cannabis (an erect herb), Humulus (hops: climbing plant). Genera with trees include Celtis and Trema. There are about 200 species. All have Leaves with stipules (basal appendage of the petiole). Plants are often dioecious (having male and female parts on separate plants). Male inflorescences are larger. Small Flowers are in cymes, actinomorphic (regular, symmetrical), have a reduced calyx, lack a corolla and are wind pollinated. Number of stamens varies. Two connate carpels are present in the Pistil and here the Ovary is usually superior. Fruit in an Achene or a Drupe.
Name derivation: Celtis used by Pliny the Elder; also Greek name for Laurel tree (23 AD–79 AD). mildbraedii – named after Gottfried Wilhem Johannes Mildbraed (1878-1945), a German Botanist and collector who explored extensively in Africa. There are 3 indigenous species of the genus Celtis in Southern Africa. The other 2 are C. gomphophylla and C. africana.
Conservation Status: L C. (Least Concern). This was originally considered a rare tree in the RSA but more trees have recently been found.
Description. This spineless Tree with its spreading Crown and watery sap may reach 30+m high. Branches tend to droop and start high up the trunk. Young branches are usually hairy and may have conspicuous pale Lenticels (a usually raised corky oval or elongated area on the plant that allows the uncontrolled interchange of gases with the environment) present. The Trunk is smooth with flaking discs and is light brown. Buttresses may be present in large trees. Young branches are long and whip-like.
Leaves. This deciduous tree has simple and alternate Leaves that are elliptic (oval in outline, being narrowed to rounded ends and widest near the middle). Each stiff, shiny green leaf is distinctly 3-veined from the base. These Veins extend about one third up the leaf. There are 3-6 pairs of lateral veins present. Net veining can be more clearly seen if the leaf is held against a strong light. The Base is slightly asymmetrical and rounded. The Apex is pointed. The Margin may be entire, completely toothed or have the teeth limited to the upper half. The leaf may reach 17 x 5cm. The Petiole (leaf stalk) is up to 9mm long. Stipules (basal appendages of the petiole) are lanceolate and short-lived. (Aug-Apr).
The inconspicuously greenish Flowers have short stalks and are actinomorphic (regular, symmetrical) and may be monoecious (separate male and female flowers present on the same tree) or bisexual. They occur on branches of the current year. Flowers occur singly or grouped together and are axillary (in the upper angle between a lateral organ, such as a leaf, and the stem that bears it). In the Male flowers: the Perianth has 4-5 lobes. Stamens are incurved only in the bud and there are 4-5 filaments arising from a hairy receptacle (is that expanded tip of the flower stalk from which the floral parts develop). Anthers are exserted after anthesis (the period or act of expansion in flowers, especially the maturing of the stamens). The Ovary is inferior or absent. The Female flower is axillary and rudimentary Staminodes (sterile stamens) are usually present. There is a single Pistil (a unit of the Gynoecium, the female element of the flower, composed of the Ovary, Style and Stigma) and the superior, sessile Ovary has a single locule containing 1 Ovule. The Style has 2 lobes. (Sep-Oct).
The small and distinctively red, fleshy, hairless, ovoid-ellipsoid Fruit is a small Drupe (a fleshy, 1-seeded indehiscent fruit with the seed enclosed in a stony endocarp; stone fruit e.g. peach) which is up to 10 x 6mm and tipped with the remains of the style (Sep+). The fruit remains on the tree until after the leaves have fallen.
Distribution & Ecology
Trees which are able to grow in low light occur naturally in KwaZulu-Natal e.g. Pigeon Valley (a natural heritage park in Durban with a high level of bio-diversity which was established to provide protection for the about 40 Celtis mildbraedii. It has 110 different species of mainly indigenous trees). The most southern location of the tree occur in a 20ha Ilanda wilds nature reserve at Amanzimtoti. These trees also occur in Swaziland, Zimbabwe (in Chirinda forest – in the Eastern Highlands on the slopes of Mount Selinda) and are widespread through Africa and Madagascar. Trees may occur in widely scattered coastal and scarp (a steep slope in the land that cuts across the underlying strata) forests up to an altitude of 1 600m. Birds including hornbills as well as primates eat the Fruit. Thick-billed weavers fragment the Seeds enabling them to eat the kernels. The Tree is the nesting site for the Black sparrowhawk.
The Wood is used for house building, and is suitable for a slow burning fuel and heavy construction. Heartwood is white to pale yellow, medium density and works reasonably well in machine tools but is difficult to nail or screw. Wood should be treated to prevent attacks by blue-stain fungus and borers. Seeds are small and germination takes up to 4 weeks. Unfortunately, viable seeds are hard to find. The Bark has analgesic properties.
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.
Ginn, P.J. McIlleron, W.G. Milstein, S. 1989. The Complete Book of Southern African Birds. Struik Publishers (PTY) LTD. Third impression 1991.
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.
Alice Notten: thanks for the help with the family name.