|Sophora tetraptera subsp. var.||Kowhai, Yellow kowhai|
Sophora Tetraptera or simply Kowhai is a moderately fast growing, evergreen that is native to New Zealand and parts of Chile. It is the national flower of New Zealand.
The young branches, leaves and flower buds are covered with a fine down that is brown in colour. During the spring, the tree is covered in racemes of golden yellow flowers. The leaves are about 8-10 cm in length and pinnate and bearing around 10-20 pairs of 20-35mm leaflets. The tree itself has an airy graceful habit.
|Standard Cyclopedia of Horticulture|
Sophora tetraptera, Ait. (Edwardsia tetraptera, Poir.). Shrub or small tree, 30, rarely 40 ft. high, with slender spreading branches: lfts. very numerous, almost sessile, obovate to linear-oblong, silky-pubescent: fls. in 2-8-fld. racemes, pendulous, about 1 1/2 in. long: pod 4-winged, 7 in. long. Spring. New Zeal., Lord Howe Isl., Juan Fernandez, Chile.—The following varieties are in cult.: Var. grandiflora, Hook. f. (Edwardsia grandiflora, Salisb.). Lfts. linear-oblong, obtuse, appressed silky-pubescent on both sides, about 1 in. long, in 10-25 pairs: fls. 1 2/3 in. long; standard shorter than wings. Var. microphylla, Hook. f. (S. microphylla, Ait. Edwardsia Macnabiana, Curt.). Lfts. orbicular-obovate to broadly oblong, usually emarginate, glabrous or nearly so above, sparingly pubescent beneath, sometimes only on the midrib, 1/4 – 1/2 in. long: fls. about 1 1/2 in. long; standard about as long as wings. CH
S. tetraptera is best planted in a sunny or semi shaded position with moist, free draining soil. It is commonly seen growing along rivers and streams in the North Island of New Zealand. It grows from around sea level up to 500m. The tree is slightly earlier flowering than its cousin, S. microphylla.
The seeds need to be treated specially to make them grow. In nature the hard outer shell of the Kowhai seed erodes away as it tumbles down streams, so the shell needs to be damaged somehow to allow water to soak into it. To allow this, one can take small nicks out of the shell using a pair of nail clippers or some similar instrument. After the chitting, the seed needs to be placed in a container of water to soak for a night.
The seeds are best planted in a coarse mix to allow for good drainage, this prevents rotting or fungal infections.
The germination period is 14-21 days.
The Kowhai can be grown from cuttings during autumn and early winter. They will take about 60-100 days to root and can be planted out in spring.
Pests and diseases
The Kowhai caterpillar is a bright-green and black caterpillar that strips the leaves of the kowhai. The treatment for such a problem is the use of an insecticide such as Orthene (NZ), Mavrik (NZ), Shield (NZ) or Super Shield (NZ).
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- Standard Cyclopedia of Horticulture, by L. H. Bailey, MacMillan Co., 1963