Alpine Avens

Botanical name: Geum uniflorum
Synonyms: Oncostylus uniflorus
Common name(s): Alpine Avens

About:
A distinctive low-growing alpine herb forming loose spreading mats through strong rhizomes. Geum uniflorum is particularly attractive, with glossy dark green leaves that often age to deep red, conspicuous golden-haired leaf margins, and relatively large solitary creamy-white flowers. Each flower has a striking crimson centre surrounded by purple anthers, making this one of New Zealand’s more ornamental alpine Geum species.

Natural habitat:
Subalpine to alpine environments up to approximately 1,800 m elevation. Found in alpine herbfields, on rocky ledges and amongst moist tussock grasslands, typically occupying cool, exposed sites with reliable moisture and good drainage.

Growing environment:
Frost, sun, wind & free draining tolerant. Prefers cool, moist conditions and performs best in well-drained alpine soils where the roots remain cool.

Endemic distribution:
Endemic to New Zealand, occurring naturally in the South Island and Stewart Island/Rakiura.

Height:
Up to approximately 20 cm tall when flowering.

Width:
Approximately 20–40 cm or more, gradually spreading through rhizomes to form loose mats.

Flowering:
November–February.
Produces solitary creamy-white to white flowers up to approximately 25 mm across, prominently marked by a crimson central disc and contrasting purple anthers.

Fruiting:
December–March.
Produces numerous small, densely hairy achenes approximately 2 mm long, with persistent hooked style remnants.

Uses:
• Alpine and rock gardens
• Alpine troughs and containers
• Native herbfields
• Tussock garden planting
• Specialist native plant collections
• High-country restoration
• Ground cover for cool alpine gardens

Appearance:
Growth habit:
A low-growing, loosely mat-forming perennial with strong rhizomes arising from a relatively stout stock. The stock is initially fleshy but becomes woody with age. Spreading rhizomes allow established plants to develop into attractive open colonies amongst rocks and surrounding alpine vegetation.

Leaves:
Basal leaves reach approximately 120 mm long and are pinnately divided, with only 1–2, occasionally up to 5, pairs of very small lateral leaflets. The terminal leaflet is much larger, approximately 10–40 mm long, with rounded teeth and sometimes shallow lobes.

The foliage is particularly distinctive. Leaves are glossy dark green when young and may fade to dark red with age. Their somewhat wavy, crenate margins are fringed with dense, coarse golden-yellow to orange-red hairs. Conspicuous white hydathodes along the margins provide another useful identification feature.

Flowers:
Each slender flowering stem carries a single flower, distinguishing the species from many other New Zealand Geum. The flowering stems reach approximately 200 mm tall and are finely hairy, with scattered longer glandular hairs.

Flowers are large in proportion to the plant, reaching approximately 25 mm across. The broad petals are white to creamy white and approximately 7–17 mm long. At the centre is a conspicuous crimson disc surrounded by contrasting purple anthers.

Fruit:
Numerous achenes develop following flowering. Each is approximately 2 mm long and densely covered with hairs, particularly around the margins. The persistent style is approximately 5 mm long and develops a hooked tip.

Ecology:
Geum uniflorum is adapted to cool, exposed high-country environments where its low, rhizomatous habit allows it to remain close to the ground and spread between surrounding alpine vegetation.

Its ability to occupy moist tussock grassland as well as exposed rocky ledges reflects a preference for reliable moisture combined with good drainage. The relatively large white flowers provide a conspicuous floral display amongst low alpine vegetation.

The fruiting heads consist of numerous hairy achenes. Their structures assist dispersal away from the parent plant.

Associated habitats:
Subalpine and alpine herbfield, moist tussock grassland, rocky ledges, alpine rockfields and other open high-country vegetation.

It commonly grows amongst tussocks and low alpine herbs where soils remain cool and moist without becoming persistently stagnant.

How to grow:
Best grown in a cool, sunny position with excellent drainage and consistent moisture during active growth. A gritty, humus-rich alpine mix is ideal, providing drainage around the crown while preventing the roots from drying excessively.

In cooler parts of New Zealand it can be grown in a rock garden, preferably amongst stones that help maintain a cool root zone. In warmer or more humid districts it is better suited to an alpine trough, container or alpine house where temperature, moisture and drainage can be controlled.

Avoid hot, humid positions and heavy soils that remain saturated. Established plants can gradually spread through their rhizomes where conditions are favourable.

Propagation:
Best propagated from fresh seed. Sow into a fine, free-draining seed-raising or alpine mixture and maintain cool, evenly moist conditions.

Established plants may also potentially be increased by careful division of rooted rhizomatous sections, although disturbance should be kept to a minimum.

Cultural use:
No specific traditional Māori uses for Geum uniflorum are widely documented. The species is primarily significant as part of New Zealand’s distinctive endemic subalpine and alpine flora.

Garden value:
An excellent specialist native for alpine gardens, troughs and rockeries. The combination of glossy green-to-red foliage, conspicuous golden-haired leaf margins and comparatively large creamy-white flowers with crimson centres and purple anthers gives Geum uniflorum considerable ornamental value.

Its low, spreading habit is particularly effective amongst rocks, small tussocks and other compact alpine plants, while its modest dimensions also make it well suited to container cultivation.