Whau
Botanical name: Entelea arborescens
Synonyms: Apeiba australis
Common name(s): Whau
About:
Whau is one of New Zealand’s fastest-growing native trees, renowned for its enormous soft leaves, masses of crumpled white flowers and unusual spiny seed capsules. It is also famous for having one of the lightest woods in the world, making it naturally buoyant.
This short-lived pioneer species quickly colonises disturbed ground and provides valuable shelter for slower-growing native trees. It is the only species in the endemic New Zealand genus Entelea.
Natural habitat:
Occurs naturally in coastal to lowland forest and shrubland, particularly in open, disturbed sites. It is commonly found on recent slips, landslides, cliff faces, boulder fields, sand dunes and along the margins of rivers, streams, lakes and lagoons.
Although most common near the coast, it also occurs inland in suitable warm districts, especially where disturbance creates open ground.
Growing environment:
Thrives in full sun and fertile, free-draining soils but also tolerates semi-shade and seasonally damp ground. It is reasonably drought tolerant once established but grows best with regular moisture.
Whau is sensitive to heavy frost and performs best in warm coastal climates or sheltered inland sites.
Endemic distribution:
Endemic to New Zealand. Naturally found on the Three Kings Islands, throughout much of the northern North Island and in scattered localities further south to Wellington.
In the South Island it is naturally confined to the Golden Bay area of north-west Nelson. It has become naturalised in many additional locations through cultivation.
Height:
Usually 3–6 m, occasionally reaching 8 m
Width:
Approximately 2–5 m
Flowering:
August–November
Fruiting:
December–June
Uses:
• Pioneer shelter tree
• Coastal revegetation
• Native restoration planting
• Wildlife habitat
• Fast-growing screening
• Educational and botanical collections
• Traditional buoyant wood uses
• Specimen tree
Appearance:
Growth habit:
A rapidly growing shrub or small tree with a broad, spreading crown and numerous upright to arching branches.
Although capable of growing quickly, it is relatively short-lived, often surviving for around 10–15 years before being replaced by longer-lived forest species.
Trunk/Bark:
The trunk is usually slender, reaching up to about 25 cm in diameter.
The bark is smooth to slightly rough, firm and grey, tearing into long fibrous strips when cut. The wood is exceptionally light, making it one of the lightest timbers produced by any tree.
Leaves:
Leaves are among the largest of any New Zealand native tree, typically 10–25 cm long but occasionally reaching 30 cm.
They are broadly heart-shaped with pointed tips and three to seven shallow lobes. The margins are coarsely and doubly toothed, while the veins are strongly visible.
The leaves are soft, thin and slightly glossy, wilting rapidly after being picked. Young stems, leaves and flower stalks are densely covered with soft whitish hairs.
Flowers:
Large, showy flowers are produced in broad clusters during spring.
Each flower has four or five crumpled white petals surrounding numerous white filaments tipped with bright yellow anthers, giving the flower a soft, fluffy appearance.
The flowers are attractive to a wide range of native insects and other pollinators.
Fruit:
The fruit is one of the most distinctive of any New Zealand native plant.
It is a rounded capsule approximately 2–3.5 cm across, densely covered with stiff black spines up to 2.5 cm long. As the fruit matures it becomes dark brown to black and remains on the tree for many months.
Seeds:
Each capsule contains numerous small orange-brown seeds.
The buoyant fruits may float on water, roll across beaches in strong winds or be transported by animals, allowing seeds to disperse into new habitats.
Ecology:
Whau is a classic pioneer species, rapidly colonising freshly disturbed ground after slips, floods and storms.
Its large leaves quickly create shade that cools the soil and provides shelter for slower-growing forest plants. As the tree matures and eventually dies, it contributes organic matter and helps drive natural forest succession.
The flowers provide nectar and pollen for insects, while the buoyant spiny fruits are dispersed by water, wind and animals.
Because it grows so quickly, it is frequently used in ecological restoration as a temporary nurse tree for establishing more permanent native forest.
Associated habitats:
Coastal forest, shrubland, slips, cliff faces, stream margins, river terraces, dune systems, lake margins and regenerating forest.
Associated species commonly include pōhutukawa, māhoe, kōhūhū, mānuka, kānuka, karamu, kōwhai and other early successional native trees and shrubs.
How to grow:
Plant in full sun or light shade in fertile, free-draining soil. It establishes rapidly and benefits from watering during its first summer.
Provide shelter from severe frost while young. Once established it tolerates dry periods and coastal exposure well.
Whau grows extremely quickly and can provide shelter for slower-growing native species within only a few years. Because of its relatively short lifespan, it is best planted as part of a mixed restoration or shelter planting.
Propagation:
Propagation is easy from fresh seed, which germinates readily without specialised treatment.
Seedlings grow rapidly and are usually ready for planting within a relatively short period. Cuttings are less commonly used.
The tree often self-seeds freely around mature specimens where growing conditions are suitable.
Cultural use:
Whau has long been valued by Māori for its exceptionally light, buoyant wood, which was traditionally used for fishing floats, net floats and other objects requiring flotation.
Some inland populations are believed to have originated from deliberate Māori plantings, reflecting its practical importance.
The genus Entelea is unique to New Zealand, making whau the sole representative of an endemic genus.
Garden value:
Whau is an outstanding native tree for warm coastal gardens and restoration projects where rapid growth is required. Its huge tropical-looking leaves, spectacular white flowers and unusual spiny fruits provide year-round interest.
It is particularly valuable as a fast-growing nurse species, creating shelter for slower-growing natives while adding bold foliage and architectural character to the landscape.