Sophora microphylla

Sophora microphylla, commonly known as kōwhai, weeping kōwhai, and small-leaved kōwhai, is a species of tree in the family Fabaceae. It reaches 25 metres (80 feet) in height, with a trunk up to 90 cm (35 in) in diameter. It is endemic to New Zealand; its range mainly covers the South Island, but is also present in the North Island. S. microphylla is found in various habitats. The species is known for its vibrant, yellow, drooping flowers and weeping branches.

Sophora microphylla was first described by the Scottish botanist William Aiton in 1789. S. microphylla is pollinated by birds; the tūī (Prosthemadera novaeseelandiae) are especially attracted to the flowers, and will travel long distances in search of them. The seeds are dispersed by gravity, wind, or by water. All parts of the plant, especially the seeds, are poisonous. The primary alkaloid responsible for the toxicity is called cytisine. S. microphylla did have a variety of uses for indigenous Māori people and European settlers, both as timber and medicinally. The flowers of the New Zealand kōwhai (Sophora sp.) are unofficially recognised as the national flowers of New Zealand.