Pectinate Button Daisy

Botanical name: Leptinella pectinata subsp. pectinata
Synonyms: Cotula pectinata, Cotula pectinata subsp. pectinata
Common name(s): Pectinate button daisy

About:
Leptinella pectinata subsp. pectinata is an endemic New Zealand creeping perennial daisy of open montane to alpine environments in the eastern South Island. It usually forms loose, diffuse patches across bare ground, although plants can develop into tighter mats where conditions are favourable.

It is characterised by dark green, almost hairless, narrowly elliptic to obovate leaves divided into narrow linear or narrowly obovate pinnae. The small white button-like flower heads are carried conspicuously above the foliage on long, slender, wiry peduncles that may reach 10 cm.

It is an adaptable member of the genus, occupying exposed stony ground, clay and loess pans, tussock-grassland openings, stable scree margins and rocky alpine herbfields.

Natural habitat:
Montane to alpine open ground from approximately 300–1,600 m elevation.

Typical habitats include bare stony ground, open clay and loess pans, sparsely vegetated areas within tussock grassland, stable scree and talus margins, fellfield and stony or rubbly herbfields.

It generally occupies open sites where surrounding vegetation is sparse and competition is limited.

Growing environment:
Full Sun, Frost, Wind, Alpine Exposure, Stony Soil, Clay & Loess, Free-draining Soil & Open Conditions tolerant.

It favours exposed, sunny sites with excellent drainage and does not require rich soil.

Although naturally occurring in cool mountain environments, it is relatively adaptable in cultivation provided excessive moisture and humidity are avoided.

Endemic distribution:
Endemic to New Zealand.

Restricted to the South Island east of the Main Divide, occurring from Marlborough south through Canterbury to North Otago.

Height:
Foliage generally approximately 1–4 cm high.

Flowering peduncles rise approximately 1–10 cm and are usually considerably taller than the leaves.

Width:
Spreads by creeping rhizomes to form diffuse patches or, less commonly, compact mats. Individual colonies may gradually extend many tens of centimetres across under favourable conditions.

Flowering:
November–February.

The white flower heads are approximately 4–8 mm across and are held conspicuously above the foliage on long, slender peduncles.

Fruiting:
December–April.

Mature cypselae reach approximately 2.1 × 0.7 mm. They are golden-brown, compressed, biconvex and vary from slightly to deeply wrinkled.

Uses:
• Native groundcover
• Rock gardens
• Alpine gardens
• Scree gardens
• Crevice planting
• Tussock gardens
• Dryland native planting
• Botanical collections
• Naturalistic high-country planting
• Restoration of appropriate montane and alpine habitats

Appearance:
Growth habit:
A creeping, perennial herb forming loose, diffuse patches or, less commonly, tight mats.

Plants are monoecious, with both female and male florets occurring on the same individual.

Leaves initially cluster around the growing tips and may remain densely crowded or become spaced by up to approximately 20 mm as the rhizomes elongate.

Branches arise singly or in radiating clusters of up to four around flowering nodes.

Short shoots are absent.

Rhizomes/Stems:
Rhizomes run at or close to the soil surface.

They are relatively stout, somewhat wiry and up to approximately 2 mm in diameter.

Rhizomes are dark and initially carry a sparse covering of long hairs, becoming almost or completely hairless with age.

Branches may arise singly or as clusters of up to four radiating outward from flowering nodes.

The root system is extensive, wiry and strongly branched, with individual roots reaching approximately 1 mm in diameter.

Flowering peduncles are particularly distinctive. They are slender, wiry, usually almost hairless and approximately 10–100 mm long, greatly exceeding the leaves. They normally lack bracts, although a single simple bract is occasionally present.

Leaves:
Leaves are usually 1-pinnatifid but are occasionally simple, measuring approximately 7–40 mm long and 2–10 mm wide.

The blade reaches approximately 30 mm long and varies from elliptic through obovate to broadly obovate.

Leaves are firmly leathery, dark green and initially finely and sparsely hairy, becoming nearly hairless with age.

The midrib is not prominently raised on the upper surface.

There are usually 1–10 pairs of pinnae, although these may occasionally be absent.

Pinnae may be closely spaced or separated and are divided completely to the rachis. They range from linear and almost cylindrical to flat and narrowly obovate.

Teeth are generally absent, although individual pinnae occasionally carry 1–3 small triangular, blunt teeth, usually concentrated on the proximal margin.

Flowers:
Flower heads are approximately 4–8 mm in diameter.

The involucre is somewhat bell-shaped and consists of approximately 12–24 oblong involucral bracts arranged in two or more nearly equal rows.

The bracts are dark green to purple-green and usually marked by one to three darker veins, with broad brown papery margins.

Female florets number approximately 12–200 per capitulum.

They are approximately 2.25–2.75 mm long, straight and white, sometimes marked by one or two dark longitudinal stripes extending along the corolla and ovary.

The corolla is considerably longer than wide and has equal teeth.

Male florets are more numerous than the female florets.

Fruit:
The fruit is a dry cypsela reaching approximately 2.1 mm long and 0.7 mm wide.

It is compressed and biconvex, becoming golden-brown at maturity.

The surface varies from only slightly wrinkled to distinctly and deeply wrinkled.

Seeds:
Each cypsela contains a single seed.

The lightweight papery fruits are dispersed principally by wind and may also be transported through incidental attachment to animals or other moving material.

Ecology:
Leptinella pectinata subsp. pectinata is an open-ground specialist adapted to sites where environmental conditions prevent the development of dense vegetation.

Its creeping rhizomes allow it to colonise gaps between stones and across exposed mineral surfaces, while its extensive wiry root system anchors plants in shallow and sometimes unstable substrates.

Its long peduncles elevate the small flower heads well above the low foliage, increasing their exposure to potential pollinators and aiding subsequent dispersal.

The subspecies is readily distinguished from L. pectinata subsp. willcoxii by its generally narrower leaves, usually more than five pairs of narrow pinnae and sparsely hairy to almost hairless rather than completely hairless vegetative parts.

It differs markedly from L. pectinata subsp. villosa, which has conspicuously dense grey-white hairs and yellow-red rather than white flowers.

Associated habitats:
Montane and alpine tussock grassland, bare stony ground, clay pans, loess pans, scree margins, talus slopes, fellfield, rocky herbfield, rubbly slopes and other sparsely vegetated high-country ground.

Associated vegetation may include native tussock grasses, small alpine herbs, cushion plants, sedges, lichens and mosses, although L. pectinata subsp. pectinata often occupies the more open areas between surrounding plants.

How to grow:
Leptinella pectinata subsp. pectinata is relatively easy to cultivate and considerably more adaptable than many specialised alpine Leptinella.

Grow in full sun in a free-draining soil or gritty mineral-rich growing medium.

Rock gardens, raised beds, alpine gardens and spaces between stones are particularly suitable.

Good airflow is beneficial, and plants should not be crowded by vigorous neighbouring species.

Avoid persistently waterlogged soils, excessive irrigation and warm, humid positions.

Under suitable conditions it spreads steadily through its creeping rhizomes and flowers freely.

Propagation:
Best propagated by division.

Rooted sections of established plants can be separated and replanted into a free-draining growing medium, where they generally establish readily.

Fresh seed may also be used when available.

Division is particularly useful for maintaining selected cultivated forms and rapidly establishing new patches.

Cultural use:
No specific traditional Māori material use is well documented for Leptinella pectinata subsp. pectinata.

Its significance lies particularly in its role within the distinctive open montane and alpine vegetation of the eastern South Island.

Garden value:
An attractive and adaptable native button daisy with considerable value for rock, alpine and naturalistic high-country gardens.

Its dark green, finely divided foliage provides a low textured groundcover, while the disproportionately long flowering stems carry numerous small white button-like heads conspicuously above the leaves.

The combination of a creeping habit, long flowering stems, tolerance of exposed conditions and relatively straightforward cultivation makes it one of the more garden-friendly montane and alpine members of Leptinella.

It is particularly effective planted amongst rocks or along the edges of gravel and scree gardens where its natural growth habit can be displayed.