Tephrosia purpurea var. sericea Benth. 1864
pronounced: tef-ROH-see-uh pur-PUR-ee-uh variety sir-ee-KEE-uh
(Fabaceae — the pea family)
subfamily: Faboideae – the bean subfamily
common name: Wild Indigo
There are 60 species of Tephrosia found in Australia, and of these 51 are native. This native is a wayside weed in quite a few parts of the island, but I have not seen large infestations of it. The specimens photographed are at the top of the path from the Rocky Bay lookout down to Picnic Bay. The species of which it is a variety has a pan-tropical distribution, and in many places is cultivated as a green manure crop.
Many species in the Tephrosia genus are poisonous, particularly to fish, from their high concentration of a chemical called rotenone. This is an odourless chemical that is used as a broad-spectrum insecticide, piscicide, and pesticide. It occurs naturally in the roots and stems of several plants. It causes Parkinson's disease-like symptoms if injected into rats and intravenously into humans. Many indigenous cultures have traditionally used these plants as fish poisons.
Tephrosia purpurea var. sericeus is a much-branched, erect, hairy perennial herb. The leaves are up to about 13 cm long, with the lanceolate leaflets opposite near the base, but becoming alternate towards the end of the stem. There are approximately 30 leaflets per leaf.
The flowers are reddish-purple, on terminal or leaf-opposed peduncles. The seed pods are slightly recurved, glabrous or softly pubescent, each with 5 or 6 seeds. The plant has nitrogen-fixing root nodules.
This plant is much used in traditional medicine. In the Ayurveda system of medicine (India) it is reckoned to be able to expel parasitic worms from the body, to be an antidote against various type of venom, to reduce fevers, to cure diseases of the liver, spleen and heart, blood disorders, tumours, ulcers, leprosy, asthma, &c. In the Unani system of medicine, a system also used in India (its practitioners can obtain recognition as medical doctors there), they use the root as a diuretic, to allay thirst, to enrich the blood, to cure diarrhoea, to help in treating bronchitis, asthma, diseases of the liver and spleen, inflammations, boils and pimples. From the leaves are made a tonic for treating intestinal troubles, and as an appetizer. The leaves are also used in the treatment of piles and sexually transmitted diseases.
Information about medicinal qualities of plants, or about their use as medicines, is for interest only, and is not intended to be used as a guide for the treatment of medical conditions.
Photographs © Donald Simpson, taken at Picnic Bay 2008-2011