Button Daisy
Botanical name: Leptinella pyrethrifolia
Synonyms: Cotula pyrethrifolia
Common name(s): Button daisy
About
Leptinella pyrethrifolia is a low-growing, creeping perennial herb in the daisy family (Asteraceae), endemic to New Zealand. It forms spreading circular patches through stout, somewhat fleshy rhizomes that run over or just beneath the soil surface. The species is especially characteristic of montane, subalpine and alpine environments, where it occupies open rocky ground, stream margins, screes and exposed ridges. Its relatively large, finely divided leaves and conspicuous white, cream or occasionally pale yellow button-like flower heads make it one of the more ornamental native Leptinella species. The typical variety, L. pyrethrifolia var. pyrethrifolia, is currently classified as Not Threatened.
Natural habitat
Naturally occurs from approximately 600–2,000 m elevation in montane, subalpine and alpine environments. It is commonly found along stream and river banks, at the bases of talus and scree slopes, on rocky ridges and around exposed rock outcrops. These habitats are typically open, cool and well supplied with moisture while still providing excellent drainage.
Growing environment
Best grown in full sun in cool, open conditions with a consistently moist but freely draining root zone. It performs particularly well in gravelly, rocky or humus-rich alpine soils where water does not stagnate around the roots. Although tolerant of exposure and cold, it generally prefers more reliable soil moisture than many lowland dryland Leptinella species.
Endemic distribution
Endemic to New Zealand. In the North Island it occurs from the Ruahine Range southward. In the South Island it is found from Nelson and Marlborough south through the eastern ranges to southern Canterbury. It is well represented in alpine and subalpine areas of the Nelson–Tasman region, including the Cobb Valley and surrounding ranges.
Height
A very low-growing plant, with the foliage generally remaining only a few centimetres above ground level. Flowering stems rise above the foliage and may reach approximately 5–7 cm or more depending on growing conditions.
Width
Spreads laterally by creeping rhizomes and can form circular patches up to approximately 1 m wide.
Flowering
November–February. Flower heads are comparatively large for the genus and are usually white or cream, occasionally pale lemon-yellow. They are often sweetly scented and stand conspicuously above the low foliage.
Fruiting
December–April. Mature fruits are small, flattened cypselae approximately 2.3 × 1 mm, becoming golden-brown at maturity.
Uses
Alpine and rock gardens
Native groundcover
Gravel gardens
Edging around rocks, paths and retaining structures
Native montane and alpine restoration
Container and trough planting
Conservation and educational collections
Ornamental planting for its attractive white or cream flower heads
Appearance
Growth habit: A creeping, mat-forming perennial developing broad circular colonies. Rhizomes are stout, approximately 1–3 mm diameter, initially dark green to purple-red and somewhat fleshy, becoming woody and more exposed with age. Several branches may radiate from flowering nodes.
Leaves: Leaves are clustered toward the ends of the rhizomes and are typically 5–40 mm long and 3–10 mm wide. They are elliptic, obovate or broadly obovate in overall outline and divided into approximately 1–4 pairs of rounded or obovate pinnae, producing a soft, fern-like appearance.
Flowers: Rounded, button-like capitula carried above the foliage on slender peduncles. Flower heads are predominantly white or cream, sometimes pale lemon-yellow, and are noticeably larger than those of many other New Zealand Leptinella. Plants are gynodioecious, with female and bisexual flower forms occurring within the species.
Fruit: Small, compressed, slightly wrinkled cypselae approximately 2.3 mm long, becoming golden-brown when mature.
Ecology
An important low-growing component of open montane and alpine vegetation. Its creeping rhizomes enable it to spread through unstable or periodically disturbed substrates such as stream margins, screes and rocky slopes. The dense, low growth habit helps the plant withstand strong winds, frost and exposure while remaining close to the relatively sheltered surface layer.
Associated habitats
Often grows in open alpine herbfields, rocky river and stream margins, scree margins, fellfield, rocky ridges and around exposed outcrops. Associated vegetation may include native tussocks, alpine herbs, cushion plants and other low-growing species adapted to cold, exposed mountain environments.
How to grow
Plant in full sun in a cool position with excellent drainage but reliable moisture through the root zone. A gravelly or gritty soil enriched with a small amount of organic matter suits it well. Avoid hot, stagnant conditions and prolonged waterlogging. It performs particularly well in alpine troughs, rock gardens, raised beds and containers where its spreading habit and flowers can be appreciated at close range. NZPCN describes it as easy to cultivate and particularly successful in pots.
Propagation
Very easily propagated from rooted sections of rhizome. Small rooted pieces can be separated and replanted into moist, free-draining substrate, where they normally establish readily. Seed propagation is also possible where viable seed has been produced.
Cultural use
No specific traditional Māori use for Leptinella pyrethrifolia is widely documented. Its modern value lies mainly in conservation, ecological restoration, alpine horticulture and the representation of New Zealand’s distinctive endemic mountain flora.
Garden value
An excellent native choice for alpine gardens, rockeries, troughs and cool-climate groundcover planting. The finely divided foliage forms attractive spreading mats, while the comparatively large white or cream button flowers provide a striking contrast during summer. Its natural occurrence through parts of Nelson and Marlborough also makes it particularly relevant for Nelson–Tasman native and ecotype-focused plantings.