Sophora microphylla is also known as Kōwhai, having showy yellow flowers in early spring. This particular Kōwhai has very small leaves (microphylla) and a tangled juvenile form, tending to straighten up and grow from an upright trunk at about four years. Kōwhai makes a good garden tree and is necessary for revegetation projects as a bird attractor. Kōwhai are suited to upper bank plantings of riparian areas. They also make beautiful shade or specimen trees.
Sophora microphylla have horn-shaped yellow flowers, which appear in early spring. Their nectar is a favourite food for Tui, Bellbird and Kererū which also eat the leaves. The pods which appear after flowering stay hanging on the tree even through winter.
The main threat that faces all wild New Zealand Kōwhai species is the risk posed through planting for revegetation and horticultural purposes of hybrid material (crossed with other Sophora species), foreign species, such as the Chilean Pelu (S. cassioides) and also of Kōwhai species outside their natural range. S. microphylla is common throughout the country, whereas many other upright species are found only in the North Island or Chatham Islands. In many places, S. microphylla occurs as isolated stands within an otherwise cleared alluvial forest, and in these situations the loss of trees over time is inevitable. Sophora microphylla and Sophora prostrata are the only forms naturally existing in Canterbury.
Kōwhai is the national flower of New Zealand. Hardy. *All parts of the plant are poisonous*