Be careful! This plant can be deadly in high doses, although moderate doses of the plant is used medicinally.
This is a tree or shrub or a much branched, scandent, scrambling woody climber, up to 10 m tall. The bark is greenish with raised white dots. All parts of the plant have a watery sap. The leathery leaves are usually in whorls of 3.The scented flowers are creamy, yellowish and orange with red marks at the base of each lobe. They are found in terminal clusters and flower September to December. The green fruits mature to light brown. During February and July the fruits (a two-horned pod) split to release seeds dispersed by the wind.
Strophanthus speciosus is not a threatened plant.
Distribution and habitat
This plant is found in forest margins in the Eastern Cape, KwaZulu-Natal, Limpopo, Mpumalanga, Swaziland and Zimbabwe.
Derivation of name and historical aspects
This plant was added to the Kirstenbosch collection in the year the Garden was founded. On the 21st of November 1913 Henry Matthew Arderne, donated a plant to Kirstenbosch. Henry Matthew Arderne (1834–1914) was the elder son of Ralph Henry Arderne (1802–1885). Part of their collection of trees, shrubs and perennials from around the world became the well known Arderne Gardens in Claremont, Cape Town in 1961.
Strophanthus speciosus was first described in 1887.
The genus Strophanthus occurs in Asia, Africa and Madagascar. Of the 38 known species, 30 occur in Africa and 6 species occur in southern Africa. The name of the genus is derived from the Greek word ‘strophos' which means twisted cord or rope, and ‘anthos‘ which means flower. This alludes to the shape of the flower. The specific name ‘speciosus' means showy, good-looking.
The seed is wind dispersed. This tree, shrub or climber provides good nesting sites for birds.
Uses and cultural aspects
A very toxic glycoside isolated from the plants of the genus Strophanthus is used as a cardiac stimulant, in moderate doses. However, the seeds, foliage and latex of this plant are said to be poisonous. The seeds were used to prepare arrow poison in Mozambique and Zimbabwe. The fruit was used as a spear poison. The roasted and pounded roots are given in powder form to cattle and humans to treat snakebites.
Growing Strophanthus speciosus
Strophanthus speciosus is easily grown from seed sown in spring or during summer. Remove the seeds from the pod and sow in trays filled with a well-drained sowing mix; seeds need only be covered lightly with the sowing mix of clean coarse sand or milled bark to stop them from blowing away The seeds should germinate within 4 to 8 weeks. Seedlings should only be transplanted after the first pair of true leaves has developed.
Semi-ripe hardwood and/or hardwood cuttings can be taken in spring or during summer. Treat with rooting hormone, and place in a well aerated medium, e.g. equal parts peat and polystyrene. Rooting period is 8 weeks, with another 2 weeks hardening off period. Water regularly but do not overwater. Prune occasionally. Spider mites can be a problem. Use appropriate measures to combat them.
References and further reading
- Coates Palgrave, M. 2002. Keith Coates Palgrave Trees of southern Africa, edn 3 . Struik, Cape Town.
- Codd, L.E. 1963. Apocynaceae. Flora of southern Africa 26. Botanical Research Institute, Pretoria.
- Leistner, O.A. (ed.). 2000. Seed plants of southern Africa: families and genera. Strelitzia 10. National Botanical Institute, Pretoria.
- Pooley, E. 1993. The complete field guide to trees of Natal, Zululand & Transkei. Natal Flora Publications Trust, Durban.
- Van Wyk, B.-E. & Gericke, N. 2000. People's plants: a guide to useful plants of southern Africa . Briza Publications, Pretoria.
- Van Wyk, B.,Van den Berg, E., Palgrave, M.C. & Jordaan, M. 2011. Dictionary of names for southern African trees. Briza Publications, Pretoria.
- Van Wyk, B. & Van Wyk, P. 1997. Field guide to trees of southern Africa. Struik, Cape Town.