Coprosma obconica

Botanical name: Coprosma obconica

Synonyms: None

Common name(s): Coprosma

About:
Coprosma obconica is a rare, densely branched divaricating shrub endemic to New Zealand. It is notable for its glossy small leaves with thickened recurved margins, mottled juvenile foliage, and distinctive flattened white fruit often streaked or blotched purple. It is one of the few New Zealand coprosmas with a characteristic blunt, nipple-like extension at the tip of the leaves. The species is highly adaptable but strongly associated with base-rich soils and habitats subject to environmental stress such as drought, flooding or frost.

Natural habitat:
Occurs in a wide variety of habitats including estuarine shrublands, braided riverbeds, lowland podocarp forest, limestone and marble outcrops, dolomite karst, and occasionally ultramafic boulderfields.

Growing environment:
Prefers sunny to lightly shaded sites with well-drained, base-rich soils. Tolerates drought, frost, periodic flooding and other stressful environments. Slow growing but long-lived.

Endemic distribution:
Endemic to New Zealand. In the North Island it occurs in scattered populations near Taihape and Masterton. In the South Island it ranges from D’Urville Island and north-west Nelson south to Otago and Southland, but is largely absent from Westland.

Height:
2–3.5 m

Width:
0.8–1 m, occasionally wider

Flowering:
April–August

Fruiting:
January–September

Uses:
• Native shrub borders
• Limestone and rock gardens
• Dry or difficult sites
• Revegetation of calcareous habitats
• Conservation plantings

Appearance:

Growth habit:
A densely branched, erect to suberect divaricating shrub with numerous wide-angled branches forming a compact, intricate framework. Juvenile and adult foliage are often present on the same plant.

Trunk and branches:
Older stems are brown to pale silver-grey, with papery bark that flakes in small irregular pieces. Inner bark is green. Young branchlets are slender, brown to silver-grey and clothed in minute hairs.

Leaves:
Adult leaves occur in opposite pairs and are broadly elliptic to oblanceolate, measuring 3.5–12 mm long and 1.5–3.5 mm wide. They are glossy grey-green, sometimes mottled yellow, with thickened margins that curve downward. The tips are blunt with a small nipple-like point, a feature unique to this species and its close relative Coprosma distantia. Juvenile leaves are larger, thinner and often mottled brown or green.

Flowers:
Male and female flowers are borne on separate plants. Flowers are small, greenish to crimson-flecked, and produced singly or in pairs on short branchlets during autumn and winter.

Fruit:
The drupes are flattened and nearly spherical when fresh, about 5 mm across, becoming obconic when dry. Fruits are greenish white, translucent white or cream and are often attractively streaked or blotched dark violet-purple. Seeds are pale and distinctly clog-shaped.

Ecology:
The fleshy fruits are dispersed by birds (frugivory). The species is adapted to environmentally stressful habitats and can persist in sites prone to drought, flooding, frost or nutrient imbalances. Although often occurring in small populations, it is remarkably resilient where habitat quality is maintained.

Associated habitats:
Limestone shrubland, marble and dolomite karst, estuarine margins, braided river terraces, podocarp forest remnants, calcareous mudstone slopes and ultramafic rock fields.

How to grow:
Grow in full sun or light shade in a well-drained site. It performs particularly well in alkaline or calcareous soils but tolerates a wide range of conditions provided drainage is good. Growth is slow, though plants are hardy and long-lived.

Propagation:
Moderately easy from semi-hardwood or hardwood cuttings. Seed germinates readily but seedlings grow slowly.

Cultural use:
There are no widely recorded traditional Māori uses for this species, though it contributes to the diversity and ecological integrity of many distinctive New Zealand shrubland communities.

Garden value:
A highly distinctive and unusual divaricating shrub valued for its compact architecture, mottled juvenile foliage and striking white-purple fruits. It is especially suited to native rock gardens, limestone plantings and collectors interested in rare New Zealand shrubs.