Euphorbia tetragona

Euphorbia tetragona, commonly the honey euphorbia and in Afrikaans the bosnaboom (bush euphorbia) and riviernaboom (river euphorbia), is a spiny succulent tree in candelabra shape growing to 13 m (SA Tree List No. 354).

This much-branched specimen grows in the Karoo Desert National Botanical Garden at Worcester in the Western Cape where it is doing very well. Sharing space with neighbouring plants that come very close is very much the norm for this tree in habitat. The trunk is cylindrical on large trees, slightly angled on younger stems.

The species distribution is in the east of the Eastern Cape and in KwaZulu-Natal tending towards the coastal region.

The habitat is dry thorn forest and scrub slopes. The species is not considered threatened in habitat early in the twenty first century. A marked decline in the average tree size and sapling numbers in the Fish River valley has been reported in a four year study by Lent, et al, published in 2010. The cause is ascribed to herbivores consuming and damaging plants, particularly baboon and black rhinoceros.

The species is similar to E. excelsa which grows in Limpopo, far to the north.

The dry stems of the honey euphorbia are burnt by traditional farmers on their maize fields. This practice yields potassium that fertilises the crops (Coates Palgrave, 2002; www.onlinelibrary.wiley.com; http://redlist.sanbi.org).