Hīnau

Botanical name:Elaeocarpus dentatus
Synonyms:Dicera dentata, Elaeocarpus hinau, Elaeocarpus cunninghamii
Common name(s): Hīnau, New Zealand Olive, Lily-of-the-valley Tree

About:
Hīnau is a handsome endemic canopy tree recognised by its leathery, finely toothed leaves, drooping clusters of fringed white flowers and oval purple-black fruit. Its broad spreading crown and contrasting foliage make it a distinctive component of coastal and lowland native forest.

The leaves are dark green above and much paler beneath, with small pits called domatia visible on the underside. Mature trees may reach approximately 20 m tall, although they are often smaller in exposed or regenerating habitats.

Natural habitat:
Common in coastal and lowland native forest, occasionally extending into lower montane forest. It grows in mature forest, secondary forest, gullies, forest margins and on sheltered hillsides.

Hīnau is most vigorous on deep, moist and fertile soils but tolerates a range of forest conditions. It is frequently associated with broadleaved and podocarp forest communities.

Growing environment:
Prefers deep, moist, well-drained soil enriched with organic matter. It grows in full sun or partial shade, although young plants generally establish best with shelter from intense exposure.

Hīnau tolerates a range of moisture and light conditions once established but performs best where the roots remain cool and the soil is protected by mulch. It has moderate frost tolerance and benefits from shelter when young.

Endemic distribution:
Endemic to New Zealand. Widespread throughout the North Island and present in the South Island as far south as South Westland in the west and the Christchurch area in the east.

Height:
Usually 10–18 m, occasionally reaching approximately 20 m

Width:
Approximately 6–12 m at maturity

Flowering:
October–February

Fruiting:
December–May, occasionally into June

Uses:
• Native forest restoration
• Large specimen tree
• Wildlife gardens
• Shade and shelter
• Traditional food source
• Traditional dye production
• Timber and tool making
• Cultural and educational planting

Appearance:
Growth habit:
A medium to large evergreen canopy tree with a broad, spreading crown. Young branches are initially upright before spreading outward as the tree matures.

Trunk/Bark:
The trunk may reach approximately 1 m in diameter. Bark is grey and relatively smooth on younger trees, becoming rougher and more irregular with age.

The pale sapwood surrounds heavy, strong, dark brown heartwood. Older trunks may become hollow.

Branchlets:
Young branchlets are covered with fine silky hairs, becoming smoother as they mature.

Leaves:
Adult leaves are leathery and generally 10–12 cm long and 2–3 cm wide, although smaller leaves may occur. They vary from narrow-oblong and oblanceolate to broadly obovate.

The upper surface is dark green and becomes almost hairless with age. The underside is off-white to pale grey-green and initially covered with fine silky hairs.

Margins are finely serrated or toothed and may be slightly wavy and rolled downward. The apex is blunt or abruptly narrowed into a pointed tip. Juvenile leaves are generally narrower than adult foliage.

Small pits known as domatia occur on the lower leaf surface near the junctions of the veins. These are one of the most useful identifying features.

Flowers:
Flowers are produced in conspicuous drooping racemes approximately 10–18 cm long. Each raceme usually carries 8–12 flowers, although as many as 20 may occur.

The individual flowers are white, waxy and approximately 8–15 mm across. Their petals are deeply divided into several narrow lobes, giving them a delicate fringed or lacy appearance.

The flowers resemble miniature lily-of-the-valley blooms and hang from slender, silky-haired stalks.

Fruit:
The fruit is a fleshy oval or egg-shaped drupe, generally 12–18 mm long and about 9 mm wide. It ripens from green to deep purple or purple-black.

Each fruit contains a very hard woody stone with a deeply furrowed and wrinkled surface.

Seeds:
The seed is enclosed within the hard inner stone. Germination may be slow because water must penetrate this durable covering.

Ecology:
Hīnau is an important food-producing tree in native forest. Its fleshy fruit is eaten by kererū, kākā, kōkako, weka, kiwi and other native birds.

Birds disperse the hard stones after swallowing the fruit or carrying it away from the parent tree. Ground-feeding birds such as weka and kiwi may be especially important dispersers of fallen fruit.

Kākā may break open the stones to feed on the developing seed, while kererū transport the entire fruit over greater distances. Hīnau trunks and canopies also provide habitat and pathways for native insects, spiders and other forest invertebrates.

The flowers provide nectar and pollen for visiting insects during spring and summer.

Associated habitats:
Coastal broadleaved forest, lowland podocarp–broadleaved forest, secondary forest, sheltered gullies, hillsides and forest margins.

Associated trees may include tawa, kohekohe, rewarewa, māhoe, kāmahi, pūriri, miro, mataī, rimu, kahikatea and

pōkākā.

How to grow:
Plant in a sheltered position with deep, moist and well-drained soil. Add composted organic material and apply a generous layer of mulch around the root zone, keeping it clear of the trunk.

Young plants appreciate partial shade or overhead shelter but gradually tolerate more sun as they establish. Water regularly during dry weather for the first several years.

Allow sufficient space for the broad crown and eventual height. Hīnau is best suited to large gardens, farms, parks, reserves and ecological restoration projects rather than confined urban sites.

Propagation:
Propagation is usually from fresh fruit. Remove the fleshy outer pulp, wash the hard stones and sow them approximately 5 mm deep in a free-draining seed-raising medium.

Keep the container moist and shaded. Germination is often slow and may take six months or considerably longer because of the hard seed coat.

Freshly collected fruit generally gives better results than seed that has been stored for long periods.

Cultural use:
Hīnau was an important traditional resource for Māori. The flesh surrounding the hard fruit stones was processed into meal and used to prepare cakes, bread-like foods and a thin gruel.

Fruit was dried, soaked or pounded before being sifted carefully to remove the hard stones. The prepared meal was wrapped and cooked for many hours, often in an earth oven.

The bark produced a brown dye which became a durable black when combined with iron-rich swamp mud. This dye was used for colouring harakeke fibre and as a pigment associated with tā moko.

The bark, wood and young stems also had practical uses. Timber was used for tools, weapons and palisades, while carefully shaped young trees could be grown into walking sticks.

In traditional accounts concerning Māui and Mahuika, hīnau was among the trees that rejected the final spark of fire and therefore could not be used to produce fire through friction.

The botanical name Elaeocarpus refers to an olive-like fruit, while dentatus means toothed and describes the serrated leaf margins.

Garden value:
Hīnau is an excellent long-lived specimen or restoration tree for spacious properties. Its broad evergreen crown provides shade and shelter, while its contrasting foliage, lacy white flowers and purple-black fruit offer year-round interest.

It is particularly valuable in wildlife gardens because the fruit attracts native birds and the canopy provides habitat for forest insects and epiphytes.