Tephrosia kraussiana is relatively easy to cultivate. Its pinkish-purple flowers will add colour to gardens.
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Tephrosia kraussiana flowers
Tephrosia kraussiana is a dwarf shrub approximately 600 to 900 mm high, with a perennial rhizome which sprouts unbranched stems each growing season after fire. Branches are straight, erect and leafy. Leaves are composed of (rarely 1) 3 or 5 leaflets of which one is terminal, the others in pairs. Leaflets are broad, linear, with close parallel veins and smooth or with very few hairs on the upper surface and more hairs on the lower surface. Stipules (leaf-like appendages at base of leaf stalk) are hairy, linear and longer than the petiole (leaf stalk). Peduncles (stalk of the inflorescence) are terminal.
Flowers are small and attractive, usually mauve to pinkish, between 7 and 10 mm long and grouped together in twos or threes in the axil of bracts. The calyx tube is 67 mm long, the lobes of the calyx are lanceolate, unequal, 14 mm long and hairy. The ovaries are 46 mm long. The style is smooth and hairless.
The fruit is a narrow pod 3040 mm long and 5 mm broad. In its natural habitat, T. kraussiana flowers in the warm, wet months between September and November.
||Left: Tephrosia kraussiana leaves
Right: Tephrosia kraussiana seeds
Tephrosia kraussiana is classified as Least Concern as it is widespread. Sub-populations occur in patches with population densities ranging between approximately 2070 individuals and are spread across large areas of the grassland. The coastal grasslands in which this species occurs are rapidly disappearing to make way for coastal development. However, several populations occur in protected lands and reserves and are not immediately threatened by habitat loss.
Distribution and habitat
Tephrosia kraussiana occurs on the KwaZulu-Natal north coast and south along the coast to East London. It is also found in the Lebombo Mountains in eastern Swaziland. It occurs predominantly in the Indian Ocean Coastal Belt biome but also inland in the Savanna. It grows in open grassland and closed shrubland in rocky loam soil. Areas in which it is found usually lie close to the sea on moderate slopes in undisturbed sites.
Derivation of name and historical aspects
The name Tephrosia is derived from the Latin word tephros meaning ashen' and refers to the grey-green or silvery leaves of many of the species in this genus (Pooley 1998). Three other genus names were proposed for Tephrosia between 1753 and 1777, namely Cracca, Colinel and Needhamia. However, in 1807, the genus name Tephrosia was founded by C.H. Persoon (born at the Cape of Good Hope and best known for his contribution to science by establishing fungal taxonomy) (Forbes 1948). There are approximately 400 species in the genus distributed throughout tropical and subtropical Africa (Brummitt 2007) and about 40 of these occur in South Africa. The species in this genus are all linked by the characteristic penninerved venation (with close, parallel veins) of the leaflets.
Tephrosia kraussiana is a fire-adapted suffrutescent (perennial with slightly woody base) species. During the growing season new aerial stems are produced from the nutrients stored in the rhizome. These stems grow and produce flowers and seed until a fire burns off the aerial shoots and only the rhizomes remain underground to resprout in the subsequent growing season. This is a vital and effective strategy in the frequently burned grassland habitat in which T. kraussiana occurs. Fortunately, the biennial burn policy in the Umtamvuna Nature Reserve favours the reproduction of this species.
Subpopulations of the species form dense to very dense stands. Recruitment appears to be very slow and new seedlings are located close to adult plants. The close proximity of individuals in a population may leave them vulnerable to land development as even localized habitat destruction may wipe out entire subpopulations.
Uses and cultural aspects
In KwaZulu-Natal, the root of Tephrosia kraussiana is used to make a lukewarm drink which is used as a remedy for persistent night coughs. It is also used to treat children's diseases. Approximately 22 species of the genus have been used as fish poisons (applied by crushing the rhizomes or leaves and dispersing it into an enclosed body of water, and then waiting for the dead fish bodies to rise to the surface) or as insecticides (by planting rows of individuals around the perimeter of the crop field to act as a deterrent to potential pests). The principal chemical properties present in this genus are rotenone, deguelin, tephrosin and toxicarol (Forbes 1948).
Growing Tephrosia kraussiana
Tephrosia kraussiana is relatively easy to cultivate. Its pinkish-purple flowers will add colour to gardens and will increase biomass production of neighbouring plants due to its soil nitrification characteristics. Plants can grow well in pots or planted out in beds. Plants are best grown from viable seed. Healthy seeds should be selected. Pods which show signs of fungal growth should not be used. Seeds should be immersed in freshly boiled water for approximately thirty seconds in order to break down the hard seed coat and promote imbibition. Seeds can then be transferred into petri dishes/multi-dishes lined with cotton wool and these should be well moistened and stored between 25 and 30ºC.
After approximately 3 days the roots should emerge. After 1.52 weeks seeds should be planted out into temporary pots with a soil depth of at least 300 mm, as roots grow rapidly and deep. Soil should be relatively fertile loamy soil which can retain a fair amount of moisture. Seedlings should be transplanted so that roots are fully covered and should be well watered daily until approximately 90 days, after which final transplanting may proceed.
References and further reading
- Brummitt, R.K. 2007. Tephrosia, In: J.R. Timberlake, R.M. Polhill, G.V. Pope & E.S. Martins (eds). Flora Zambesiaca 3 (Part 3):1250. Royal Botanic Gardens, Kew.
- Forbes, H.M.L. 1948. A revision of the South African species of the genus Tephrosia Pers. Bothalia 4: 9511001.
- Germishuizen, G. 2000. Fabaceae. In O.A. Leistner (ed.), Seed plants of southern Africa: families and genera. Strelitzia 10: 262303. National Botanical Institute, Pretoria.
- Herman, P.P.J., Retief, E., Koekemoer, M. & Welman, W.G. 2000. Asteraceae. In O.A. Leistner (ed.) Seed plants of southern Africa: families and genera. Strelitzia 10: 101170.
- Pooley,E. 1998. A field guide to wildflowers of KwaZulu-Natal and the Eastern Region. Natal Flora Publications Trust, Natal Herbarium, Durban.
Threatened Species Programme