Life Gardens

Wednesday 21 March 2018

Other-worldly tree for the birds

Sophora hails from New Zealand where it is valued by birds for its nectar
Sophora hails from New Zealand where it is valued by birds for its nectar

Gerry Daly

A small tree dripping mustard-yellow flowers from every twig, sophora is a real eye-catcher, and it is in flower these days. It is a very distinctive tree, almost other-worldly in its unusual appearance. And it does come from the far side of the globe in New Zealand.

Strangely, it is part of the familiar pea family, which includes shrubs such as broom and gorse and trees such as laburnum and robinia. All of these examples have typical pea-shape flowers, which have wings and a keel pointed upwards. In contrast, sophora has all its petals pointed down to make a tubular flower.

This shape has evolved to facilitate birds that come to drink the sweet nectar from the flowers, and transfer pollen in the process. Drops of nectar can be shaken from the flowers sometimes.

As many as 10 species of birds native to New Zealand use the sophora nectar as a food source in spring. But there are no nectar-feeding bird species here or in Europe.

Each flower is held by a brown-green calyx and the flowers are grouped in dense clusters. The little tree is covered with flowers, to the extent of hiding the small, evergreen leaves. The leaves are divided into about 20 pairs of leaflets.

The sophora species were highly valued by the Maori people. They called it kowhai (which is also the Maori word for 'yellow') and this is sometimes used as a common name.

When it is not in flower this species of sophora, or kowhai, is not anything like as decorative. It forms a small, upright tree with its fern-like, 15cm leaves. These are dark-green and the tree tends to melt into the background, but it still has an unusual look to it.

It is often planted against a sunny wall to encourage more flowers, but it looks better as a stand-alone specimen. Though not fully hardy, it is hardy in most parts of the country, especially in coastal areas.

It can be damaged by hard frost in its early years, but it is usually fine as it grows older, and mature plants survived the severe winters of a few years ago.

It should be well staked because it is prone to damage by wind-rocking. While it can tolerate wind reasonably well, roots can be broken, which leads to a slow decline during which it flowers profusely and produces masses of flowers and lots of seeds. This can happen with its relative laburnum too.

Sophora grows best in open, well-drained, sandy or gravelly soil, not too fertile and definitely not wet in winter.

My new tree took a hammering!

Q. My darling four-year-old boy took a hammer to a newly planted semi-mature tree which I believe is a red oak or beech. It is badly damaged. Should I wrap it with something? It was planted last autumn so I hope it survives. Do you think it is alive? C O'Flynn, Cork

A. He obviously has an inquiring mind! The tree will survive. Wrap the exposed areas with strips of black bin bag. Wrapping immediately after the damage is done is better as it preserves the cambium where healing comes from. But if the cambium is dried out and dead on the bare areas, it will repair from the sides of the wounds.

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