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Kowhai

Threat Status :

Non Threatened

Species :

Sophora chathamica

Species Authority :

Sophora chathamica Cockayne

Qualifier :

 

Threat Category :

Not threatened

Family :

Fabaceae

*Common Name :

Kowhai, coastal kowhai

Distribution :

Endemic. A primarily coastal species known from North, South and Chatham Islands but probably only indigenous to the northern half of the North Island, where it is common in the west from the Tongaporutu River to Te Paki. In the east it is abundant south to about Thames, so far it has not been reported south and east of there. Very common around Auckland, the Hauraki Gulf and from Port Waikato south to Kawhia. There are some inland occurrences in the lower Waikato Basin. Disjunct occurrences around Wellington, the Chatham Islands and Whanganui Inlet may result from deliberate plantings by the Maori.

Habitat :

Primarily a species of coastal forest, often on cliff faces or banks overlooking estuarine rivers or inlets. Occasionally found in swamp forest.

Features :

Tree up to 20 m tall, with one or more trunks. Branches spreading to upright. Juveniles weakly flexuose. Leaves on seedlings and juveniles moderately to densely leafy, 4.4-9 x 4.4-7.5 mm, orbicular to very broadly obovate, crowded, usually overlapping. Adult leaves up to 150 mm long, imparipinnate, usually pubescent, hairs, straight, appressed. Leaflets 25-55, crowded and overlapping, 6-16 x 4-8 mm, broadly elliptic, broadly obovate, broadly ovate, obovate to orbicular, distal leaflets usually smaller than proximal. Inflorescences racemose with up to 11 flowers. Calyx 8-10 x 10-13 mm, cupulate. Flowers yellow, keel petal blade 29-43 x 9-11 mm, wing petal blade 25-42 x 9-11 mm, standard petal blade 25-34 x 20-25 mm; petals with distinct claws 4-6 mm long. Fruit 50-180 mm long, 4-winged, brown, with up to 12 seeds. Seeds 5.5-8 x 4.-5. mm, oblong, elliptic to orbicular, yellow to light yellow-brown.

Similar Species :

Distinguished from all other Kowhai species by the absence of a divaricating/filiramulate juvenile stage; with leaflets 6-16 x 4-8 mm; and by the distal leaflets usually smaller than proximal, crowded and overlapping (especially toward distal end), with leaflets broadly elliptic, broadly obovate, broadly ovate, obovate to more or less orbicular, with all parts moderately hairy.

Flowering :

August-November

Fruiting :

October-September

Alternative Names :

Sophora microphylla microphylla var. chathamica (Cockayne) Yakolev

Propagation Technique :

Easy from seed, provided the hard seed shell is nicked first with a knife or rubbed with sandpaper to expose the endosperm. Soaking seed treated this way overnight often helps speed up germination. Can be grown with difficulty from cuttings.

Threats :

The main threat that faces all wild New Zealand kowhai species is the risk posed through planting for revegetation and horticultural purposes of hybrid material, foreign species, such as the Chilean Pelu (S. cassioides) and also of kowhai species outside their natural range. However, S. chathamica seems to be very common throughout its range, and is adequately protected within a range of reserves and land set aside for conservation purposes. The nativity of the Chatham Island populations is not clear, and though assumed to be planted by Maori, because this assertion needs further study and the trees are culturally significant they require direct management. Few (if any Chatham Island) plants can be said to exist in truly secure habitats.

Where to Buy :

Commonly available at most commercial nurseries. A popular native tree for larger gardens. Very commonly sold in garden centres, where it is often sold as either S. microphylla or S. tetraptera. Some plants with a superficial resemblance to S. chathamica and offered by nurseries usually as S. microphylla or S. tetraptera have, upon closer inspection, turned out to be the closely related Chilean pelu (S. cassioides).

 

* Please note that Common Names are not standardised.

The Kowhai New Zealand's National Flower   by Alan Jolliffe

If there is one flowering plant that New Zealanders call their National Flower it is the Kowhai. It grows naturally throughout the dryer areas of New Zealand and because it is so popular it is planted in almost every garden.

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 the 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 the easiest to grow and fastest to flower when grown from seed. It is probably the most commonly available in the
Nursery industry.

As a garden plant the 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 the 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 the 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 the old leaves drop off as the new leaf buds break and develop into new branchlets. All the old leaves are replaced to provide a fresh green look. The leaves are divided along the 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 the 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 the colour is a golden sulphur yellow. The calyx, which holds the petals in place, is a yellowish/green colour that adds further colour to the flowers.

Tuis and bellbirds love these flowers and visit them to drink the sweet nectar. Unfortunately these birds, in their haste, tear the flowers to pieces.

Following flowering seed pods are produced. These 4 winged pods house a single seed in specially constructed compartments. Each pod may have up to 8 seeds. When mature the seeds may be gathered and sown quickly to ensure they germinate.

Pests and diseases include the Kowhai moth whose larvae eat the leaves and the seeds. Scale insects may invade the Kowhai and they are easily controlled by spraying with all seasons spraying oil.

The Kowhai is the best known NZ Native flowering tree and one of the most beautiful. As a small tree it is excellent in many small gardens where light foliage cover is required and a burst of colour in spring when it smothers itself with blooms.

The botanical/Latin name has the following meanings. Sophora is an Arabian name for a tree with pea shaped flowers and tetraptera means 4 winged seed. Previously it was included in the genus Edwardia. Kowhai is the Maori name and means yellow.

Maori also recognised the Kowhai as an important plant. Its medicinal properties were explored by the Maori and poultices were made from bark and applied to wounds and tumours. An infusion of barks (a tea) from the Kowhai and manuka was used to treat internal pain, bruises and broken limbs. Wood ash from the Kowhai was used to treat ringworm.

The Maori are said to have regulated the planting of potatoes by the flowering time of the Kowhai.

The wood of the Kowhai is valuable as is it is very durable. Logs have been used straight from the bush and used in construction without any special treatment.

As an individual tree the Kowhai is a superb garden plant. It is small enough for even the smallest of gardens but it is large enough to make an impact. As a garden tree there is none better in spring.

In the larger landscape the Kowhai makes a big success. Mass plantings of Kowhai make a tremendous impact on the scenery. This can best be seen in some of the naturally occurring stands in the Rangitiki area of the North Island.

Plantings of the Kowhai should be encouraged throughout NZ and in other places around the world to ensure this icon of New Zealand plants is able to show us its best each spring.



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