There are however 2 main species of Kowhai. Sophora tetraptera, North Island Kowhai and Sophora microphylla, South Island Kowhai. Where these plant grow side by side in wild natural hybrids also exist. Many hybrids have occurred in gardens as well. Additionally there are 2 naturally occurring varieties of S. micropyhlla and numerous forms, some of which have been named.

The North Island Kowhai, Sophora tetraptera is easiest to grow and fastest to flower when grown from seed. It is probably most commonly available in Nursery industry.

As a garden plant North Island Kowhai is excellent. With its fast upright growth it is ready to flower in 3-5 years. It does not go through all twiggy juvenile stages of other Kowhais. It is easy to grow and will succeed in almost all garden situations. It will reach a height of 4-6m with a trunk diameter of 30-60cm.

In wild S. tetraptera grows naturally along forest margins, in lowlands and hill country and alongside streams. Its natural altitude range is from sea level to 450 metres.

Often described as an evergreen tree it losses all its leaves for a very short period each year. In spring all old leaves drop off as new leaf buds break and develop into new branchlets. All old leaves are replaced to provide a fresh green look. The leaves are divided along mid rib into a number of leaflets. Each leaflet is oval shaped 25-30mm long and 5-7mm wide. It creates a feathery look. The new young branchlets and young foliage covered with dense silky hairs which are smooth to touch.

The most distinctive feature is its flower. Each spring large bright yellow flowers appear in pendulous clusters of 5-7 on naked branches. These showy clusters appear in great profusion. Individual flowers are up to 6cm long and colour is a golden sulphur yellow. The calyx, which holds petals in place, is a yellowish/green colour that adds further colour to flowers.