General Info – summary

This Tree, with its relatively watery latex and smooth trunk, is up to 15m high.  Simple, alternate and ovate to roughly triangular Leaves have serrated margins.  The distinctively thin petiole is up to 10cm long.  The very small greenish yellow monoecious and unisexual Flowers develop in spikes.  Female flowers occur at the base of the spikes.  The 3-lobed Fruit is a woody, globose capsule with 1-2 carunculate inedible seeds. 

Description

Croton megalobotrys

Previous Names: Croton gubouga.

SA Tree No. 329.

Common names: (Afr) Groot-Koorsbessie, Koorsboom.  (Eng) Fever-berry, Fever-berry croton, Fever Bark, Fever Bark Tree, Fever Bark, Fever Bark Tree, Large Fever-berry, Lowveld Croton.  (Northern Sotho) Motsibi.  (Setswana) Moêpê, Mosôôlê, Motsêbê, Phukutsa.  (Tshivenda) Muruthu.  (Xitsonga) Xunguxungu.

Conservation: National Status: L C. (Least Concern).  Assessed: 2005 (R.H. Archer and J.E. Victor).

Family Euphorbiaceae (Spurge family) e.g., the well-known exotic poinsettia – Euphorbia pulcherrima) with its normally bright red colour due to bracts not perianth parts.  The plants may be trees shrubs or herbs.  Trees up to 15m high and the trunk may reach 46cm wide.  Spines are paired or absent. Latex/watery sap present.  Trees may be monoecious (male & female on the same plant) or dioecious (male and female parts on separate plants).  Genera on this site include Croton, Euphorbia and Spirostachys.  Leaves are absent or reduced, may fall early and may be largish.  When present most leaves are simple e.g., Spirostachus.  When compound the leaves are always palmate (hand-like: compound with leaflets arising from one point).  Leaf shape varies from ovate to lanceolate.  Leaf arrangement is in spirals, opposite or alternate.  Stipules may be spinescent e.g., Euphorbia sp. or may be lost early e.g., Spirostachus.  At the leaf base, the veins are single (midrib) or are 3-5 veined e.g., Macaranga.  Domatia may occur e.g., in Alchornea.  Leaves may smell of almonds if crushed e.g., Croton sp.  When leaves are present margins are usually irregularly serrated.  Petioles may be swollen at 1 or both ends.  2 glands often occur at base of leaves e.g., Spirostachys.  In some Euphorbiaceae plants CAM (Crassulacean acid metabolism) photosynthesis can occur.

The unisexual Flowers are Actinomorphic (Regular, symmetrical).  They may lack a calyx or a perianth (calyx and corolla).  Inflorescences develop terminally or in leaf axils.  Flowers may develop in 1. racemes (a simple, unbranched, indeterminate inflorescence with pedicellate – stalked flowers along the axis that open in succession towards the apex) e.g., Macaranga & Croton.  2. cyathia (cup-shaped Euphorbia inflorescence that appears as a single flower but is, in fact, a collection of reduced flowers.  (They usually have 5 joined bracts outside: up to 10 brightly coloured nectar glands which may have petal-like appendages or brightly coloured bracts followed by 5 much reduced male flowers at the base of each bracteole.  In the centre is a much-reduced female flower).  3. spikes (simple indeterminate inflorescence with sessile flowers on a single unbranched axis opening in succession towards the apex e.g., Spirostachys).  4. panicles (determinate or indeterminate, much branched inflorescence with stalked flowers.  The branches of a panicle are often racemes.  Petals are absent e.g., Macaranga.  Male flowers may lack an ovary and have 1-8 or many e.g., Croton, exerted stamens.  Fewer Female flowers have a superior ovary with 1 ovule per 1-to many locules and each locule has 1 or 2 ovules.  3 styles may be present.  Most flowers are insect pollinated.  Fruit may occur in long racemes or small lobed, dehiscent or indehiscent capsules.  Seeds may have a caruncle (a fleshy structure attached to the seed) and may be poisonous.

Name derivation: Croton resembling ticks – referring to the seeds of some species.  megalobotrys – large cluster / big bunches – referring to the flower head.  There are about 11 species of the genus Croton in southern Africa.

Conservation: National Status: L C. (Least Concern).  Assessed: 2005 (R.H. Archer and J.E. Victor).

Tree

This Tree may be densely leafy and up to 15m high but is usually smaller, and watery latex is present.  It may also be a large, soft bush.  The pale grey Trunk with relatively smooth Bark (photo 852) becomes fissured with age.  Young smooth 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 allow the uncontrolled interchange of gases with the environment) here (photo 852E) in vertical lines.  Young branches have short-lived hairy scales.

Leaves

The simple, alternate and ovate to roughly triangular Leaves can range from less than 3cm up to 20cm long and 2 to 13cm wide.  They are not significantly bicoloured, being dark green above and slightly lighter below.  Silvery green stellate hairs occur – more on the lower, slightly rough surface.  On the lighter upper surface, the hairs tend to diminish with time.  The Apex is attenuate (showing a long gradual taper) of the apex in this case.  A slender drip-tip may form.  The Base is the widest part of the leaf.  It is slightly rounded to cordate (heart shaped) or square.  There are 3-7 side veins arising from the base (photo 853) and up to 5 pairs of lateral veins are present.  On the lower side of the base are 2 wing-shaped glands next to the petiole.  The rough serrations on the Margin are irregular.  The slender, hairy and the velvety Petiole (leaf stalk) is up to 10,5cm long (photo 853).  The 1 or 2 hairy Stipules (basal appendages of the petiole) are initially present but soon fall.

Flowers

The small, white to pale greenish-yellow Flowers are about 7mm wide.  They are contained at the ends of twigs in Spikes (simple indeterminate inflorescence with sessile flowers on a single unbranched axis opening in succession towards the apex) or Racemes (simple, unbranched, indeterminate inflorescence with pedicellate – stalked flowers – along the axis that open in succession towards the apex and may reach 17cm long.  Plants are monoecious (having both male and female reproductive organs on the same plant).  The Male flowers, usually with petals present, are alone or are most numerous towards the end of each inflorescence.  Filaments are inflexed in the bud but straighten in the mature flower.  There is no Ovary present.  The Female flowers, lack petals and are located at the base of the inflorescence.  The slightly accrescent (continuing to grow after flowering) calyx is smaller than in the male flowers and flowers lack petals.  The superior Ovary has a single Ovule in each locule.  (Sep-Dec).

Fruit

Whitish woolly hairs only initially cover the almost spherical, initially light green Fruit that is an obscurely 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).  The large fruit is about 4cm wide and ripens to a yellowish brown.  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 carunculate (have a fleshy outgrowth of the seed near the micropyle) Seeds.  (Dec-Jan).

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 – KNP, northern Namibia, Botswana (common in the Okavango Swamp), Zimbabwe, central and southern Mozambique, Angola, Zambia, Malawi and Tanzania.  It is usually a riverine tree or found in alluvial flat areas and fringes of swamps.  It occurs at low to medium altitudes – below 1 100m.  Herbivores, especially Elephants eat the bark, roots and branches.

Ethnobotany

The low density, light coloured Wood is soft, white and generally useful.  Golden yellow oil, extracted from the Seeds is used in soap making.  Bark and seeds were once used to treat malaria.   Bark and seeds are used medicinally and 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).  Birds or other animals do not eat the Seeds.

References

Archer, R.H. & Victor, J.E. 2005. Croton megalobotrys Müll.Arg. National Assessment: Red List of South African Plants version 2020.1. Accessed on 2023/01/23.

Burrows, J.E., Burrows, S.M., Lotter, M.C. & Schmidt, E. 2018. Trees and Shrubs Mozambique.  Publishing Print Matters (Pty) Ltd.  Noordhoek, Cape Town.

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. Jacana, Johannesburg.

van Wyk, B. & van Wyk, P. 1997 Field guide to Trees of Southern Africa. Struik, Cape Town.

http://www.zimbabweflora.co.zw/speciesdata/species.php?species_id=134790

http://www.ispotnature.org/species-dictionaries/sanbi/Croton%20megalobotrys

http://eol.org/pages/1146908/overview

http://www.biodiversityexplorer.org/plants/euphorbiaceae/croton_megalobotrys.htm

http://www.rroij.com/open-access/antiplasmodial-and-radical-scavenging-activities-of-croton-megalobotrys-.php?aid=65800

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.

http://posa.sanbi.org/flora/browse.php?src=SP