Tree of the month

Kāpuka.

GROWING HABIT

Griselinia littoralis can grow up to 20m, but don’t be deterred. Often, it will grow much less than this, particularly in areas with coastal exposure. Its attractive leaves are a glossy yellow-green on top, ranging from 6 to 14cm long.

Male and female flowers, both greenish, are produced on separate trees: male flowers are around 5mm in diameter, and females slightly smaller. They’ll pop up from midspring to late summer. Dark black or purple berries are likewise small, and will appear in midsummer to ripen through autumn and winter.

GROWS BEST IN?

Ka¯puka is found throughout New Zealand, ranging from the Far North to Rakiura, and from lowland through to high hills or subalpine forest. It’s a hardy plant most commonly found in exposed coastal areas, from sea level up to around 900m altitude (typically in larger quantities and at lower altitudes in the South Island).

Ka¯puka is from the same genus as Griselinia lucida (puka, shining broadleaf; not to be confused with Meryta sinclairii). Ka¯puka, though, is more cold tolerant.

IN THE GARDEN

Ka¯puka is a clean plant with relatively little leaf litter, a fresh green colour and subtropical texture, so it’s popular as a garden plant and makes an ideal hedge.

It is best pruned in summer and recovers quickly if damaged. It can even be grown in tubs.

Ka¯puka is often the go-to species for revegetation projects on tough and exposed coastal sites. The plant is commonly seen as wind-clipped bastions within the ranks of coastal forest.

CARE & MAINTENANCE

Ka¯puka is a tough, long-lived and resilient native, and will survive on very little nutrients (like many of our native plants). Exposed areas are no problem; sea breeze and wind exposure are all in a day’s work.

However, it does prefer freedraining, light loamy soil, and thrives in full sun or semi-shade. It tolerates temperatures from -10°C up to 35°C, which gives scope for much of New Zealand. It enjoys good growth in high rainfall areas, but can get root rot in poorly drained soils and humid regions.

HOW TO PROPAGATE

Forest ecologist Dr John Wardle notes that ka¯puka can be easily propagated from seed collected in the late autumn and stratified for six weeks. It can also be propagated from summer cuttings of half-ripened wood.

IN THE WILD

I have seen many large, old broadleaf trees amongst the mata¯i in Isolation Gulley near Sawcut Gorge. The old trees have thick, rough, textural bark, and are common in subalpine podocarp forests of southeastern Marlborough.

Research has shown that Griselinia littoralis is the most important food for red deer in Pureora Conservation Park – they eat more broadleaf than any other plant species.

Unfortunately, this also prevents regeneration. Many of the leaves are eaten from the forest floor when they drop from foliage on branches that are out of reach.

GLOBAL AUDIENCE

Although native to New Zealand, Griselinia littoralis is also well-known in other corners of the world. Kapuka is, in fact, widely cultivated as an ocean windbreak in areas with mild climates, such as the south coast of Britain and the Faroe Islands.

Videos of “New Zealand privet” are even uploaded to YouTube by English plant nurseries! ✤