Small Button Daisy

Botanical name: Leptinella pusilla
Synonyms: Cotula perpusilla, Cotula angustata
Common name(s): Small button daisy, button daisy

About
Leptinella pusilla is a very small, creeping perennial herb in the daisy family (Asteraceae), endemic to New Zealand. It spreads through slender underground rhizomes, sending up compact tufts of finely divided leaves that form low patches amongst grassland and open rocky vegetation. The leaves are typically light green but often develop conspicuous brown to bronze pigmentation, particularly toward their bases. Male and female flowers occur on separate plants. Despite its diminutive appearance, it is well adapted to exposed, relatively dry environments and can extend from coastal sites to subalpine country.

Natural habitat
Occurs in open, sparsely vegetated habitats from the coast to approximately 1,200 m elevation. Typical sites include gravel and stony ground, sandy areas, dry or sparsely vegetated tussock grassland, short turf and sheltered ground around or beneath rock outcrops. Although it reaches subalpine elevations, it is more frequent at lower elevations. 

Growing environment
Best suited to sunny, open positions with freely draining soil. Gravelly, sandy or stony substrates closely reproduce its natural conditions. Established plants have excellent drought tolerance, making the species useful in dry native gardens, rock gardens and other exposed situations where taller vegetation will not overwhelm it. 

Endemic distribution
Endemic to New Zealand. In the North Island it occurs from the Moawhango area south through the south-eastern portion of the island to Cape Palliser and the southern Wellington coast. In the South Island it occurs primarily east of the main ranges, from the Richmond Range in Marlborough south to Foveaux Strait. Herbarium records include Nelson, Marlborough, Canterbury, Otago, Southland and Westland land districts. 

Height
Extremely low-growing, generally only a few centimetres above the ground. Leaves are approximately 10–60 mm long and flowering peduncles approximately 10–30 mm tall. 

Width
Spreads laterally by underground rhizomes to form patches or low carpets. Older botanical descriptions record individual patches reaching approximately 30 cm across, although established colonies may gradually spread further where conditions are favourable. 

Flowering
August–November. The tiny button-like flower heads are green to yellow-green. Male heads are approximately 3–5 mm across, while female heads are initially around 2–4 mm across and enlarge during fruit development. 

Fruiting
October–January, occasionally continuing into March. Female flower heads expand to approximately 8 mm across as the fruit develops. The fruits are small papery cypselae, approximately 1.6 × 1 mm, initially pale before becoming brown and smooth at maturity. 

Uses

• Native groundcover for sunny, dry sites

• Rock gardens and gravel gardens

• Native alpine and dryland plantings

• Low-growing planting between rocks and around larger native species

• Restoration of appropriate dryland and tussock-grassland habitats

• Conservation planting for an endemic species classified as At Risk – Declining

• Useful small-scale groundcover where excellent drainage and low vegetation are desired 

Appearance
Growth habit: A diminutive, creeping, tuft-forming perennial. Pale, wiry rhizomes generally run beneath the soil and produce short upright shoots bearing clusters of leaves. Branching of the rhizomes is relatively uncommon.

Leaves: Finely divided and approximately 10–60 × 3–10 mm. The blades are light green, lanceolate to obovate and range from nearly hairless to densely hairy. They carry approximately 8–15 pairs of small oblong to obovate pinnae. Brown or bronze pigmentation is often conspicuous on the lower pinnae and may sometimes extend over much of the leaf.

Flowers: Small, inconspicuous, button-like heads carried on hairy peduncles approximately 10–30 mm long. Plants are dioecious, with male and female flower heads produced on separate individuals. Florets are predominantly yellow-green.

Fruit: Small, papery cypselae approximately 1.6 mm long, becoming brown and smooth at maturity. The female flower head develops into a compact, nearly spherical fruiting structure. 

Ecology
A specialised component of New Zealand’s open dryland, grassland and rocky vegetation. Its underground rhizomes allow it to persist in exposed sites while maintaining most of the plant close to ground level. The small papery fruits are dispersed primarily by wind and possibly through attachment to animals or other moving material. Habitat loss and modification of dryland environments are important concerns for the species, reflected in its current At Risk – Declining conservation status. 

Associated habitats
May occur amongst short native tussock and grassland vegetation, open gravel and stony surfaces, sandy ground and around exposed rock outcrops. Depending on locality, it can occur alongside other low-growing native herbs and turf species adapted to relatively open environments. It is sometimes found together with the closely related Leptinella serrulata, which can make identification difficult. 

How to grow
Grow in full sun to light open shade in very free-draining soil. Gravelly or sandy soils are particularly suitable. Avoid sites where vigorous grasses or taller groundcovers can smother the small plants. Once established, Leptinella pusilla is remarkably drought tolerant. It is considered comparatively easy to cultivate when provided with appropriate drainage and is particularly well suited to rockeries, gravel gardens and dry native plantings. 

Propagation
Vegetative propagation by division or rooted pieces of the creeping rhizome is the most practical method in cultivation. Seed can also be produced, but because male and female flowers occur on separate plants, both sexes must be present for successful sexual reproduction. Many cultivated populations consist of only one sex and therefore rarely produce viable seed. 

Cultural use
No well-documented traditional Māori use specific to Leptinella pusilla is widely recorded. Its principal contemporary importance is ecological and conservation-related as a distinctive endemic component of New Zealand’s native dryland and grassland flora.

Garden value
An attractive but subtle native groundcover for gardeners interested in New Zealand’s smaller and less commonly cultivated flora. Its finely divided green-to-bronze foliage creates a delicate, fern-like texture close to the ground, while its tiny button-shaped flowers add interest in spring. Its tolerance of sun, exposure and drought once established makes it particularly valuable for rock gardens, dry banks, gravel gardens and naturalistic native plantings. Because wild populations are declining, responsibly sourced cultivated plants also have worthwhile conservation and educational value.