Sophora: Kowhai                                                                                        Family: Papilionaceae (pea or Legume family)

There are 30 species.of Sophora found in temperate and subtropical regions of both Hemispheres. The New Zealand species are endemic. There is debate as to their correct botanical classification. There are 2 common trees; and species status has been given to a number of distinct divaricating shrubs, confined to localisedareas within New Zealand . All are deciduous.

Sophora tetraptera is a tree up to 12 metres tall. Leaves can be up to 15 cm long with leaflets 3.5 X 8mm. The golden yellow flowers are up to 5 cm long. There is no divaricating juvenile form. Its distribution is on lowland stream sides and forest margins on the eastern side of both islands.

Sophora microphylla is a tree to about 10 metres tall. Leaves are up to 15 cm long, however what differentiates it from Sophora tetrapetera, is the small leaflets are never longer than 1 cm. The flowers are slightly smaller as well and are coloured pale to golden yellow. It may have a divaricating juvenile form. Its distribution is through all of New Zealand in lowland and lower montane forests, along rivers, forest  skirts and open places.

Sophora prostrata is a prostrate or bushy shrub up to 2 metres tall. Leaves may be up to 2.5 cm log, usually smaller. Leaflets are no larger than 4mm.

 

Sophora microphylla 0463 - Sophora prostrata Dwarf Kowhai
The bark and leaf of sophora microphylla Sophora prostrata .A divaricating habit

 

Kowhai is another of New Zealand ’s deciduous trees, actually termed hemideciduous. It loses its leaves just prior to flowerin. In August and September the flowers arise from branches naked of leaf. All New Zealanders who live close to nature welcome the kowhai flowers, as they signal the arrival of spring.

The flower of the kowhai is the national flower of New Zealand.

Like all  legumes Kowhai have bacterial nodules on their roots that transfer gaseous nitrogen into soil soluble nitrates, an excellent fertiliser. Note the similarity of the seed pod to the other legumes peas and beans.

The seed is adapted for dispersal by floating which accounts for its abundance on stream sides, where floods carry the seeds throughout the catchments system. Native birds such as pigeon feed on the seed pods using the tough seeds as gizzard stones to masticate their food. Pigeons have been observed eating the leaf as well.

The seeds of kowhai have a dormancy mechanism, that being, their tough seed coat (testa) that is impervious to water unless nicked with a sharp knife or scalpel. Soak overnight   and sow in a warm, sunny spot. Germination should proceed within 20 days. A plant 30-40 cm high can be attained one year after germination.

It is said that the Kowhai sprung from the shreds of the cloak of tohunga Ngatoro-I-rangi of the Te Arawa waka on its arrival to Aotearoa. The legend says that a young tohunga asks a girl to marry him while they sit under the bare branches of a Kowhai tree in the month of August. She replies that she will only marry him if he can perform some brilliant act. “I will show you what I can do. I will cause this tree to spring instantly into flower before your eyes.” He uses all his powers and the tree bursts into bloom, his final touch causing a ring of yellow blossoms to appear around the dark hair of the girl. Ever since, say Te Arawa, the Kowhai has flowered on bare and leafless branches

 

There is a saying in the Bay of Islands: “When the kowhai is in flower, the fish are up the Waitangi”

P. Williams Te rongoa maori.

 

The Kowai is met with principally on the banks of rivers: In the season of spring this tree makes a beautiful appearance , being entirely covered with bright chrome or golden coloured  flowers which hang corymbriated, and succeeded by long pendulated pods, the especial food of the Tui and other birds. Its beauty is not dimmed by the reflection in the adjacent stream.

J. Polack. New Zealand : being a narrative of travels and adventure in that country between the years 1831 and 1837.

 

0421 - Sophora microphylla.Kowhai kowhai
Sophora microphylla flowers
The seed of Sophora microphylla with their tough testa or seed coat.



Kowhai is the national flower of New Zealand. The seeds of this genus have a dormancy mechanism, that being their tough seed coat (testa) that is impervious to water unless nicked with a sharp knife or scalpel. The smaller seeded species do not need this treatment as the seed coat is thin and diffusion of water and gases occurs readily. Soak overnight  and sow in a warm, light spot. Kowhai are simple for children to grow and observe.  The change from flower to seed pod over a summer is noticeable and striking and with their high germination rate and hardy nature they make excellent studies for students of all ages.

In the wild the seed, which floats, can be seen washed up on beaches after  a storm. They are also eaten by birds, probably as roughage. Their journey through the acid environment of the gut dissolves away some of the testa and is an aid to germination.

Sophora microphylla

 

kowhai flower to seed

kowhai make excellent plant studies for students of all ages.

 

Bookstore

Plant heritage NZ Order on line

I recommend the following books on New Zealand native plants
100 Best NZ Native Plants for Gardens
The Reed Field Guide to New Zealand Native Trees
Trees and Shrubs of New Zealand
Gardener's Encyclopaedia of NZ Native Plants
A Photographic Guide to Ferns of New Zealand
N
ew Zealand Trees and Shrubs: A Comprehensive Guide to Cultivation and Identification
From Weta to Kauri: A Guide to the NZ Forest
Which Native Forest Plant? (Which S.)

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