Melicytus alpinus aka Porcupine Shrub

Melicytus alpinus is a small evergreen shrub from New Zealand’s South Island. It belongs to the violet family, Violaceae. Its common name is porcupine shrub. Kew records its life form as a subshrub. It comes from a temperate region. Older names include Hymenanthera alpina and Hymenanthera dentata var. alpina. These names refer to the same plant described here.

The shrub forms a compact mound with a dense branch structure. Its stems end in spines and carry few leaves. The evergreen leaves remain through the year. The RHS describes plants reaching about 2 feet [0.6 metres] tall. Its wider garden size range reaches 1.6–3.3 feet [0.5–1 metre]. The listed spread is also 1.6–3.3 feet [0.5–1 metre]. Allow for that width when choosing a planting space. Plants take 10–20 years to reach their full size.

Small cream flowers appear in spring, hanging below the branches. White berries follow the flowers. The flowers are tiny, rather than large or bold. The spiny stems, sparse leaves, and berries give the plant its distinct form. The supplied sources give no evidence about eating the fruit. They also give no species-level information about toxicity. The berries should not be treated as edible from this evidence alone.

Grow this shrub in full sun with very free drainage. The RHS favours sandy soil for cultivation. Its soil listing also includes loam. Acid, neutral, and alkaline soils all fall within its stated range. Soil moisture can range from dry to moist, provided water drains freely. Once established, the shrub can withstand drought. South-facing and west-facing sites suit its light needs. The RHS lists both exposed and sheltered positions as suitable. Its H5 rating covers most UK sites, including severe winters. That rating corresponds to minimum temperatures of 5–14°F [−15 to −10°C].

The RHS suggests this shrub for rock gardens and coastal planting. Its low, mounded shape suits those listed garden settings. Routine pruning is not needed. For propagation, sow seed in autumn in a cold frame. The RHS reports few usual pest or disease problems. These points suggest a plant with modest routine care needs. Good drainage remains a key part of its stated growing requirements.