General Info

Tree that may reach 7m high. Stem loses its older branches. Crown is candelabra shaped. There are no mature Leaves – the young stems photosynthesise. Flowers are in Cyathia.

Description

Euphorbia sekukuniensis.

RSA Tree No. 343.

Common names: Sekhukuni Euphorbia, Sekhukhune, Candelabra Tree.

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 (inflorescence with many flowers appearing as a single flower – like a sunflower). In Euphorbia they appear as cyathia (where 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). Plants may be monoecious or dioecious and the regular, unisexual Flowers may or not have a perianth. Male flowers have 1-many stamens with free filaments and stamens with up to 4 pollen sacs. Female flowers have a superior ovary with 1-many locules – each with up to 2 ovules. Fruit is a capsule or nut(s). Seeds may have a caruncle (a fleshy structure attached to the seed) and may be poisonous.

Name derivation: Euphorbia – after Euphorbus: physician to the king of Mauretania (approximately 10 BC). sekukuniensis – where plant was found (Sekhukhuneland) – named after 19th century chief: Sekukuni. There are over 300 Euphorbia species in southern Africa.

Conservation Status: Rare. 2009. (Raimondo et al.). Threatened by highly destructive open cast mining for platinum in calcium rich rocks. None of the location areas are in conservation areas.

Tree

The usually single upright Tree may reach a height of 7m. The Crown is a dense candelabra shape. It has 4-5 angled, slightly constricted branches at intervals of about 20cm. There is a continuous horny strip of united spine shields along each margin. These widen at each pair of spines and taper towards the one above. The paired, stout and rigid Spines are up to 8mm long. These spines are initially red. The branch diameter is small – up to 2cm and branches are up to a metre long. The branches are slightly constricted into parts up to 20cm long. Branchlets may occur just above these constrictions. The older branches fall off and leave behind a visible hole that remains there for some time (photo 812). This branch loss results in a branch-free Stem. The uniformly grey, smoothish Bark surrounding the holes is slightly raised. The holes are no longer visible in the older, now dark grey bark and here Lichen may be present.

Flowers

The Flowers occur in an inflorescence called a Cyathium (name given to the cup-shaped inflorescence that appears as a single flower but is a collection of reduced flowers). In this plant, the cyathia are horizontal on very short stalks. The cyanthia are yellow and occur near branch tips just above the spines on the ridges. Sepals and petals are absent. Each cyathium is composed of unisexual flowers surrounded by bracts and often glands. These flowers are monoecious (having both male and female reproductive organs on the same plant) but not on the same flower. Thus, individual flowers are either male or female and are both found within an Involucre (one or more whorls of small leaves or bracts standing underneath a flower or flower-cluster). The Male Flowers are reduced to a single Stamen. The longitudinally dehiscent Anther has 2 Thecae (pollen sacs). The solitary Female Flower has a single Pistil with a single, 3-locular, superior Ovary and 3 persistent Styles. Each locule has a single Ovule. Male flowers surround the lone female flower. Pollinators are attracted by surrounding coloured, modified bracts and nectar glands. The tree is insect pollinated. (Aug-Sep).

Fruit

Fruit, at maturity, is a woody, 3-lobed Capsule (a dry fruit resulting from the maturing of a compound ovary which usually opens at maturity by one or more lines of dehiscence) on a stalk. The capsule is about 8mm wide. The 3 persistent Styles are visible. The fruit is red when mature and has 3 distinct Lobes. (Sep-Dec).

Distribution & Ecology

These plants are common on rocky outcrops in the Leolo / Lubombo mountains – usually at an altitude of 900-1 300m. The tree is endemic to Sekhukhuneland (between Lydenburg and Polokwane in Limpopo) and in the Steelpoort River Valley as far as the Olifants River (a tribute to the Limpopo River) Valley.

Ethnobotany

Latex is present and is milky and caustic. It is very poisonous and can cause blistering, allergic reaction or even blindness. Do not collect wood from this tree to use in a Braai.  Plants are succulent and cactus like but the true cactus lacks both the paired spines and latex.

References

Coates Palgrave, M. 2002. Keith Coates Palgrave Trees of Southern Africa, edn 3. Struik, Cape Town. p533.

Lawrence, G. H. M, 1951. Taxonomy of Vascular Plants, The Macmillan Company, New York. Tenth Printing 1965. p565.

Palmer, E. & Pitman, N. 1972. Trees of southern Africa, Balkema, Amsterdam, Cape Town. p1174.

Schmidt, S. Lotter, M. & McCleland, W. 2002. Trees and Shrubs of Mpumalanga and the Kruger National Park. p284.

van Wyk, B. & van Wyk, P. 1997 Field guide to Trees of Southern Africa, Struik, Cape Town. p38.

http://redlist.sanbi.org/species.php?species=574-325

http://hpra-atom.wits.ac.za/atom-2.1.0/uploads/r/historical-papers-research-archive-library-university-of-witwatersrand/e/9/7/e97e0ad91d200dc3e46c14cb85f813730573c4c1a2c2520d37a27aa8bfe0c0c4/A1655-E9-01-jpeg.pdf

http://www.iucnredlist.org/details/30346/0

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