Euphorbia tirucalli

General Info – Summary

This spineless, succulent, straight stemmed Tree with its rough grey bark is up to 8+m high.  Greenish branchlets are cylindrical.  Small Leaves fall early.  Unisexual yellow Flowers lack a perianth and are in cyathia.  Each male flower has 1 stamen.  Female flowers have 1 pistil.  Coloured bracts and nectar glands attract insects.  Fruit is a small globose, 3-lobed, woody capsule releasing the smooth, brown seeds.

Description

Previous Names: Euphorbia media, Euphorbia rhipsaloides, Euphorbia scoparia.

SA Tree No. 355.

Common names: (Afr) Kraalmelkbos, Kraal-melkbos, Kraal-naboom (hedge plant).  (Eng) Hedge Euphorbia, Rubber Euphorbia, Rubber-hedge Euphorbia, Rubber Tree, Tirucalli Tree.  (isiXhosa) Umhlonthlo.  (isiZulu) Umduze, Umndue, Umsululu, Umunde wasehlanzeni.  (Northern Sotho) Motlalamela.  (Setswana) More-ômotala.  (siSwati) Umdvute.  (Tshivenda) Mutungu.  (Xitsonga) Mahumbana, Motsêtse, Sehlaresetala.

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 (calyx and corolla).  This family has many herbs, and in the tropics, shrubs and trees, including succulents and climbers, are more common.  Apart from Antarctica, members of this family are present in all continents.  Trees are up to 15m high, and the trunk may reach 46cm wide.  Spines are paired or absent. Latex/watery sap is present.  Genera on this web site include Croton, Euphorbia and Spirostachys.  Leaves may be largish, absent or reduced, and may fall early.  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 the margins are usually irregularly serrated.  Petioles may be swollen at 1 or both ends.  Two glands often occur at each leaf base e.g., Spirostachys.  In some Euphorbiaceae plants, CAM (Crassulacean acid metabolism) photosynthesis can occur.  Here stomata only open at night to reduce water loss.  Inflorescences develop terminally or in leaf axils.  Most flowers are insect pollinated.  Plants may be monoecious (male & female on the same plant) or dioecious (male and female parts on separate plants).  The unisexual Flowers are Actinomorphic (Regular, symmetrical).  They may lack a calyx or a perianth (calyx and corolla).  Generally, plants in this family contain a large amount Phytotoxins (toxic substances produced by plants).

Name derivation: Euphorbia – after Euphorbus (50BC-AD19): physician to the king of Mauretania (NW Africa).  tirucalli – thirkkalli / Tiru-Calli – from Malayalam: an official language in India.  Hendrik van Rheede was first to record the plant in 1679.  Carl Linnaeus (1707-1778) named this plant in 1753.  He was responsible for development of the modern binomial nomenclature.

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

Tree

This is a variable shaped, spineless, succulent shrub or a straight cylindrical Tree.  It is usually up to 8m but may reach 12m high and may grow in dense stands.  The straight Stem (photo 55) has a slightly rough, longitudinally ridged, grey Bark (photo 57).  Bulges, swellings or knobs may occur on old trunks.  Green Branches often develop from near the base of the stem (photo 55).  The thornless Crown of hairless, usually green, small (up to 7mm wide) Branchlets (a small branch or division of a branch – especially a terminal division; usually applied to branches of the current or preceding year) develop on the stem and branch ends.  Here they may become an almost spherical broom-like mass (photo 50).  Individual branchlets are narrow – up to 8mm wide with much divided segments.  Branchlets are usually cylindrical (photo 51 under Leaves).  An orange form is also available at nurseries (photo 14 – under Leaves).  These branchlets are opposite, alternate or clustered at the ends of the main branches.  They help with the plant identification.  They appear to grow without a pattern.

Leaves

he small Leaves (photos 14, 51 & 54) are up to 12 x 2mm.  They are seldom noticed as they fall early.  Recent leaf scars initially form marks on young stems.

Flowers

Inconspicuous flowers develop in angles of branches or at tips of branches in clusters of small yellow/blue Cyathia (a cyathium is the name given to the cup-shaped inflorescence that appears to be a single flower but actually is a collection of reduced flowers, bracts and glands).  In photo 462, each of the “buds” is an undeveloped cyathium.  All flowers within the cyathium are unisexual and lack a perianth (calyx and corolla).  Many Male Flowers surround the single Female Flower.  Each male flower has only one protruding Stamen (each visible stamens in photos 565 & 471) and is produced from a single male flower.  The 2 longitudinally dehiscent, yellow Anther thecae (pollen sacs) are distinctly not parallel (photo 565).  The solitary Female Flower has only a single Pistil (with a single trilocular ovary, 3 pollen receiving stigmas and 3 persistent supportive styles).  Here the Ovary has one pendulous Ovule in each Locule.  The surrounding coloured (light blue in photo 565 & 471), modified bracts and nectar glands attract pollinators.  (Jun- Sep).

Fruit

When mature, the globose (spherical or nearly so) green to pink and slightly 3-lobed Fruit is a small green Capsule (a dry fruit resulting from the maturing of a compound ovary that usually opens at maturity by one or more lines of dehiscence).  It is up to 8mm wide and rests on a short (10mm), often-bent stalk.  The capsule becomes woody at maturity and splits open to release the smooth, brown Seeds that are marked with white.  (Sep-Jan).

Distribution & Ecology

This resilient Plant is found up to an altitude of 1 500m in most places from the Eastern Cape (where it is not common) to KwaZulu-Natal, Gauteng, Mpumalanga, and Limpopo.  It is also located around old kraal sites and in South East and North Mozambique, Siswati (Swaziland), South East Botswana, Angola, Congo, Northern Namibia, Rwanda, Zambia and northwards to central Africa.  These plants occur on rocky riverbanks, rocky outcrops and bushveld (a mixed woodland region (900-1 500m altitude) in the hot, dry north-east of South Africa and adjoining countries.  They may occur in open woodland.  Some Birds build their nests in the trees.  Birds including Doves, Crested Guineafowls and Franklins eat the Seeds.  Vervet Monkeys consume the Fruit.  The Black Rhino is the only mammal that may browse the plant.  Milky caustic Latex is present.  This possibly evolved as a deterrent to herbivores.  This African tree was probably taken to India by early Portuguese navigators.

Ethnobotany

Parts of the Tree have been used as an insecticide and fish poison.  An inferior quality rubber has been extracted from the Sap.  An unsuccessful attempt has been made to commercially extract usable petrol-like products from the plant.  Since it grows in areas that cannot be used for normal agriculture this was a positive consideration.  Trees serve as an effective barrier when planted as a hedge around local huts and villages.  Cattle avoid this tree, and it also keeps moles away.  The poisonous Latex causes burning and blistering of skin and eye contact can result in blindness.  Rinse any contact with copious quantities of water.  If swallowed it can be fatal.  The borer resistant Wood is hard and used as roof struts.  Propagation is by fresh seeds, truncheons or cuttings.  Apart from being partly frost sensitive, these plants have few problems.  They are survivors that prefer full sun.  Local medicine makes dangerous use of this plant.

References

Archer, R.H. & Victor, J.E. 2005. Euphorbia tirucalli L. National Assessment: Red List of South African Plants version 2024.1. Accessed on 2026/02/05.

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.

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.plantzafrica.com/plantefg/euphorbtirucal.htm

https://en.wikipedia.org/wiki/Euphorbia_tirucalli

https://www.hort.purdue.edu/newcrop/duke_energy/Euphorbia_tirucalli.html

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