Kōwhai (Sophora) are small, woody legume trees native to New Zealand growing throughout the country. There are eight species, most growing to around 8 metres high and have fairly smooth bark with small leaves. Sophora microphylla and S. tetraptera are more commonly known. Their natural habitat is beside streams and on the edges of forest, in lowland or mountain open areas. All parts of the kōwhai, but particularly the seeds, are poisonous to humans.br/br/The name kōwhai comes from the Māori word for yellow as the kowhai flowers were a source of yellow dye to early Maori in New Zealand. Māori would also use the kōwhai tree for medical purposes where the bark was heated in a calabash with hot stones, and made into a poultice to treat wounds or to treat bruising, and even seal bites.