Solanum laciniatum < Species index > Streblus banksii
This article was first published in the Tararua Tramper Volume 95, # 6, July 2023
July in the hills with Michele Dickson, Chris Horne
Sophora microphylla, Kōwhai,
Photo: John Barkla
Origin of the botanical names ‘Sophora’ comes from the Arabic word 'sufayra', the name of a leguminous tree; 'microphylla', meaning 'small-leaved', comes from the Greek words mikros ('small') and phyllon ('leaf'). Kōwhai is a member of the Fabaceae family which includes our native broom species in the Carmichaelia genus, kākābeak and the peas and beans which we eat.
Distribution and habitat
Kōwhai is endemic to New Zealand. It grows on Te Ika a Māui / North Island, Te Waipounamu / South Island and Rekohu / Chatham Island but not on Rakiura / Stewart Island. It grows on sand dunes, river and lake edges and fertile stony slopes up to about 500 m altitude. Its seeds float and are durable in salt water - the result is that kōwhai is recorded in Chile and in the south Atlantic on Gough Island, and seeds have been seen on beaches in the Kermadec Islands.
Growth habit
Kōwhai is a tree up to ca. 25 m tall with a trunk up to 60 cm or more in diameter with smooth grey-brown bark. The finely hairy yellow or orange twigs of young plants have a densely tangled ‘divaricating’ form that may last for many years. The adult leaves, up to 15 cm long, bear 20-40 pairs of closely-spaced small, round leaflets per twig. The stalked and finely hairy leaflets are 4.5-12.5 x 2.3-5.7 mm. Kōwhai is semi-deciduous, so many leaves fall off in winter.
Reproduction
Kōwhai is the te reo word for yellow – the colour of its spectacular flowers. They appear in spring – 2-5 cm long, bright yellow, large, drooping and in groups of four to ten flowers on sometimes leafless branches. They produce 15 cm-long brown pea-like, winged and hairy seed pods each with up to twelve golden-yellow seeds 5-8 mm long. The pods split to disperse the seeds.
Uses
Kōwhai in flower are beautiful garden plants. The wood has been used to make tool handles, fence posts and the prongs and heads of hay rakes. An ointment of crushed, boiled kōwhai bark was used to bathe bruises. The bark, leaves, flowers and sap have been used medicinally but beware – treat all parts of the plant as possibly toxic. The petals can be used to produce a yellow dye. Tūī, korimako / bellbird and bees pollinate kōwhai while seeking the nectar and kererū eat the petals and leaves. Kōwhai moth caterpillars eat the leaves.
Where can you find kōwhai?
Look for it in local reserves, in the Tararua, Remutaka and Aorangi ranges or wherever you tramp.
In The Hills 2023-06 < Index chronological > In The Hills 2023-08