The Tree may reach 15m high and has a watery latex. The simple Leaves are serrated. The very small greenish yellow Flowers are monoecious and in racemes. Fruit is a globose capsule and Seeds may be carunculate.
Croton megalobotrys, Croton gabouga.
RSA Tree No. 329.
Common names: Large Fever-berry, Fever-berry Croton, Fever-berry, Fever Bark, Groot-Koorsbessie, Koorsboom.
Conservation Status: L C. (Least Concern). 2009 (Raimondo et al.).
Family: Euphorbiaceae (Euphorbia family e.g. exotic poinsettia – Euphorbia pulcherrima). This family has about 275 genera and 7 500 species. Our local genera containing trees include Alchornea, Croton, Euphorbia, Macaranga and Spirostachys. This family has plants that may be herbs, shrubs or trees and latex is often present. Leaves, when not rudimentary, are usually alternate and simple with free stipules. Inflorescences are situated terminally or axillary. They are mostly in cymes (a broad, more or less flat-topped, determinate flower cluster, with central flowers opening first). They may be grouped in spikes (simple indeterminate inflorescence with sessile flowers on a single unbranched stalk), thyrses (the main axis grows indeterminately, and the branches have determinate growth) or pseudanthia (inflorescences with many flowers appearing as a single flower – like a sunflower).
Name derivation: Croton resembling ticks – referring to the seeds of some species. megalobotrys – large cluster – referring to the flower head. There are about 11 species of the genus Croton in southern Africa.
The Tree may be densely leafy and up to 15m high but it is usually smaller. It may also be a large, soft bush. The Trunk is slender and smooth. The bark becomes fissured with age. Young branches are hairy, tend to droop and may have visible raised whitish lenticels (are usually raised corky oval or elongated areas on the plant that allows the uncontrolled interchange of gases with the environment) in vertical lines. The tree has watery latex.
The simple, alternate and ovate to roughly triangular Leaves can range from less than 3cm up to 18cm long and up to 13cm wide. They are not significantly bicoloured. There are 3-5 veins arising from the base and up to 5 pairs of lateral veins present. Silvery green stellate hairs occur – more on the lower, slightly rough surface. The Apex tapers gradually to a slender tip. The 3-5 veined Base is the widest part of the leaf. It is slightly rounded to cordate (heart shaped), to square. On the lower side, there are 2 glands next to the petiole. The rough serrations on the Margin are irregular. The Petiole (leaf stalk) is up to 7cm long, slender, hairy and the velvety. The 1 or 2 Stipules (basal appendages of the petiole) are initially present. These soon fall away.
The very small, pale greenish-yellow Flowers are contained in Racemes (a simple elongated inflorescence with stalked flowers). Flowers are monoecious (separate male and female flowers on the same plant). The Male flowers are alone or are the most numerous and towards the end of each inflorescence. Filaments are inflexed in the bud but not in the mature flower. There is no Ovary present. The Female flowers may be located at the base of the inflorescence. These flowers lack petals and the calyx is smaller than in the male flowers. The superior Ovary has a single Ovule in each locule. (Sep-Nov).
This almost spherical, light green Fruit is a 3-lobed, woody Capsule (a dry fruit resulting from the maturing of a compound ovary, which usually opens at maturity by one or more lines of dehiscence) about 3,5cm wide. The calyx is slightly accrescent (the calyx continues to grow after the corolla has fallen). The capsule is initially slightly hairy and is perched on a small stalk. The yellowish brown mature fruit contains about 2 Seeds. The seeds are carunculate (have a fleshy structure attached to the seed) and these are not eaten by birds or other animals.
Distribution & Ecology
These Trees are found in Limpopo, Mpumalanga e.g. near the confluence of the Limpopo and Pafuri rivers and also in the Letaba rest camp, Mozambique, northern Namibia, Botswana, Zimbabwe, Angola, Zambia, Malawi and Tanzania. It is usually a riverine tree or found in alluvial flat areas, fringes of swampy areas and occurs at low to medium altitudes below 1 100m. Elephants eat the bark, roots and branches.
The Wood is soft, white and generally useful. Oil extracted from the seeds is usable for soap making. Seeds have a purgative property. Bark and seeds used as a fish poison. Tests at the University of Botswana indicated that extracts from bark produced a significant suppressive anti-plasmodial (anti-malaria) effect. Bark extracts may also reduce HIV-1 replication. Fruit is used as a biofuel (fuel produced by current biological processes).
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.
Schmidt, S. Lotter, M. & McCleland, W. 2002. Trees and Shrubs of Mpumalanga and the Kruger National Park.
van Wyk, B. & van Wyk, P. 1997 Field guide to Trees of Southern Africa, Struik, Cape Town.
http://www.sciencedirect.com/science/article/pii/S0378874116303981 :contains an extract from an article in the Journal of Ethnopharmacology Volume 191, 15 September 2016, Pages 331-340.