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Tree Botanics

Kowhai Previous

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Other Names: (Sophora microphylla/tetraptera)

The Kowhai, member of the Papilionaceae family (pea) is one of New Zealand's most beautiful & widely acclaimed trees.  Typically a small deciduous spreading tree reaching physical dimension of up to 10m (microphylla) & slightly larger at 12m (tetraptera).  It occurs throughout New Zealand in open forests & along streams & lakes throughout the North & South Islands (microphylla - tetraptera having a much more restricted distribution, in the North Island from the east cape southwards to the Ruahine Range), around lake shores, forest outskirts & open places in lowland & lower montane regions.  It ascends from sea level to 760m. Juvenile plants go through a distinctly divaricating stage (branching or spreading widely from a point or axis, as branches or on an insect's wings; diverging) which can last from 5 - 10 years or even longer varying from one geographical region to another.  This period lasts for the longest time with Kowhai originating along the dry Eastern side of the South Island.  This structural identifying feature/anomaly does not occur in tetraptera which does not pass through a juvenile stage and reaches greater dimension than its microphylla cousin. The kowhai can have a main trunk of up to 60cm in diameter with greyish-brown, rough & furrowed bark. The leaves are 7.5 - 15cm in length & have 20 - 40 pairs of small leaflets; the leaflets usually being less then 1cm long.  Tetraptera leaflets are much larger ranging from 1.5 - 3.5cm long & occur in pairs of only 10 -20. kowhai-flower-tuiYellow flowers appear from August - October on bare branches, the leaves follow directly after flowering.  Flowers occur in racemes (an inflorescence having stalked flowers arranged singly along an elongated unbranched axis, as in the lily of the valley) numbering 4 - 6 (up to 4.5cm long) & the kowhai is dioecious (having the male and female reproductive organs borne on separate individuals of the same species).  In tetraptera flowers appear longer (up to 5.7cm long).  Kowhai flowers are sought by bellbirds & tuis.  The jointed, 4-winged pod contains 6 or more large yellow seeds.