Houhere

Botanical name: Hoheria sexstylosa
Synonyms: None
Common name(s): Houhere, Long-leaved lacebark, Ribbonwood

About:
A graceful evergreen endemic tree distinguished by its narrow grey-green leaves, often pendulous branch tips and strongly contrasting juvenile and adult growth forms. Hoheria sexstylosa can reach approximately 18 m tall and is principally a tree of riparian forest from the central North Island to the northern South Island.

Young plants form a twiggy, tangled, sub-divaricating shrub with small, rounded and deeply toothed or lobed leaves. As the tree matures it develops much longer, narrower foliage and a more conventional crown, often with attractively drooping outer branches. White flowers appear from late summer into autumn and typically contain six styles, the feature from which the species name sexstylosa is derived.

Natural habitat:
Coastal, lowland to montane riparian forest.

It is particularly associated with damp forest along rivers and streams, alluvial terraces, valley floors and other sheltered sites with reliable soil moisture.

Although established trees are reasonably hardy, young plants generally favour sheltered, moist environments.

Growing environment:
Frost, Sun, Partial Shade, Damp Soil & Free Draining tolerant. Prefers sheltered sites and consistently moist, fertile soils, particularly while establishing.

Endemic distribution:
Endemic to New Zealand.

In the North Island it occurs naturally from the northern Waikato and Coromandel Peninsula south through the central and southern North Island to Wellington and Wairarapa.

In the South Island its natural distribution is less certain because cultivated plants have extensively naturalised. Populations in north-west Nelson and inland Marlborough are considered probably natural.

Height:
Up to approximately 18 m tall.

Width:
Approximately 4–8 m depending on age, site and growing conditions.

Flowering:
February – May
Produces white flowers approximately 18–25 mm across, either singly or in small clusters of 2–5.

Fruiting:
April – August
Produces dry, flattened, winged mericarps dispersed by wind.

Uses:
• Riparian restoration
• Stream and river-margin planting
• Lowland forest restoration
• Specimen tree
• Shelter planting
• Native woodland gardens
• Pollinator planting
• Damp-site revegetation
• Large native gardens
• Ornamental planting

Appearance:
Growth habit:
A much-branched evergreen tree with a dark grey-brown mature trunk and relatively slender branches.

Young growth is reddish-brown and more densely covered with fine, star-shaped hairs.

Juvenile and subadult plants have a distinctive filiramulate, sub-divaricating to fully divaricating growth form, producing a tangle of slender interlacing branches.

Mature trees develop a taller, more open crown with ascending branches whose outer tips are frequently pendulous. Juvenile-type growth may reappear as reversion shoots following damage to mature trunks.

Leaves:
Juvenile leaves are small, approximately 10–30 mm long and 10–25 mm wide, broadly ovate to almost circular. Their margins are irregularly and deeply divided into 3–5 lobes or coarse teeth.

Adult foliage is dramatically different. Leaves are approximately 50–150 mm long and 10–60 mm wide, although most are conspicuously longer and narrower than those of Hoheria populnea.

Adult leaves are lanceolate to ovate-lanceolate, generally dark to grey-green above and paler beneath. The base narrows into a wedge shape, while the apex is usually acuminate but may occasionally be blunt or rounded.

Margins are finely and relatively closely toothed, providing a useful distinction from the broader, more coarsely toothed leaves of H. populnea.

Flowers:
White flowers are approximately 18–25 mm in diameter and are produced singly or in clusters of 2–5.

The five white petals are approximately 10–15 mm long, obliquely oblong and commonly notched at their tips.

The calyx is bell-shaped and densely covered with stellate hairs.

Flowers usually possess six styles and six carpels, although 5–7 may occasionally occur. The anthers are white.

The tendency to possess six styles gives the species its botanical epithet sexstylosa, meaning “six-styled”.

Fruit:
Flowers develop into clusters of flattened, dry mericarps.

Each has a brown body approximately 4.5–6.5 mm long and a conspicuous orange-yellow wing approximately 3–8 mm long.

The wing curves abruptly outward and enables the mature fruit to be dispersed by wind.

Ecology:
Hoheria sexstylosa is primarily associated with moist riparian forest and contributes to the structure of native vegetation along waterways and alluvial environments.

Its relatively rapid growth makes it useful in the development of forest cover, while the dense juvenile branching provides shelter and structural complexity close to ground level.

The numerous white flowers provide resources for insects and other pollinators.

Hybridisation is an important feature of the species. In northern Waikato and Auckland it naturally overlaps and hybridises with Hoheria populnea. Further south it frequently occurs alongside and hybridises with Hoheria angustifolia.

Some intermediate plants can therefore be difficult to identify reliably.

Associated habitats:
Riparian forest, lowland broadleaf forest, montane forest, river terraces, stream banks, alluvial forest, valley floors, forest margins and moist secondary forest.

It is especially characteristic of sheltered forest associated with waterways and reliably damp soils.

How to grow:
Relatively easy to cultivate where adequate moisture and shelter are provided.

Plant in full sun to partial shade in fertile, moist but reasonably well-drained soil. Riparian positions and sheltered valley sites are particularly suitable.

Young plants benefit from protection from severe exposure and drying winds until their root systems are established.

It is less adaptable to dry or exposed conditions than Hoheria populnea, so regular watering during establishment is beneficial.

Once established it develops into a handsome medium to large native tree with attractive drooping outer branches.

Propagation:
Easy from fresh seed.

Collect mature winged fruits and sow into a fine, moist, free-draining propagation mix.

Fresh seed generally germinates readily, and young plants soon develop the characteristic twiggy, divaricating juvenile growth form.

For restoration work, locally sourced seed is preferable, particularly because the species hybridises readily with related Hoheria and has naturalised beyond parts of its original range.

Cultural use:
Like other New Zealand lacebarks, Hoheria sexstylosa has strong fibrous inner bark characteristic of the genus.

Lacebark fibres have traditionally been utilised for cordage, tying and textile purposes, although specific documented uses of H. sexstylosa are less extensive than those recorded for some other houhere species.

Garden value:
An attractive native tree particularly suited to damp, sheltered gardens and riparian landscapes.

Its most interesting ornamental characteristic is the transformation from the tangled, small-leaved juvenile plant into a taller tree with long, narrow foliage and graceful, often weeping branch tips.

The white late-summer and autumn flowers provide additional seasonal interest at a time when many other native trees have finished flowering.

It is particularly useful for larger gardens, stream margins and naturalistic woodland plantings, although care should be taken when planting outside its natural range because it can self-seed, naturalise and potentially hybridise with other Hoheria species.