Banks Peninsula Button Daisy
Botanical name: Leptinella minor
Synonyms: Cotula haastii, Cotula minor
Common name(s): Banks Peninsula button daisy
About:
Leptinella minor is a small endemic New Zealand creeping daisy restricted today to Banks Peninsula, although historic herbarium records show that it formerly also occurred on the Canterbury Plains.
It forms open to diffuse patches of finely divided dull green foliage, usually with conspicuous brown pigmentation on the lower pinnae. Its small white button-like flower heads are borne on slender stalks above the foliage for much of the year.
The species is naturally uncommon and highly range-restricted, but can still be locally abundant in suitable open rocky habitats on Banks Peninsula.
Natural habitat:
Rock outcrops, rubbly ground and shallow skeletal soils from sea level to approximately 600 m elevation.
It typically occupies open sites with little surrounding vegetation and may also occur in open grassland.
Competition from taller vegetation, particularly introduced grasses, can reduce suitable habitat.
Growing environment:
Full Sun, Partial Shade, Coastal Exposure, Wind, Frost, Dry Soil, Free-draining Soil, Rocky Ground & Open Conditions tolerant.
It performs best in sunny, well-aerated situations with a fertile but sharply drained soil.
It dislikes prolonged humidity and is generally better suited to exposed rock gardens and open ground than sheltered, stagnant conditions.
Endemic distribution:
Endemic to New Zealand.
Now naturally restricted to Banks Peninsula in Canterbury, South Island.
Historic herbarium specimens show that it was formerly also present on the Canterbury Plains.
Height:
Usually approximately 1–5 cm tall, with flowering peduncles rising to around 2–5 cm.
Width:
Spreads through creeping rhizomes to form open or diffuse patches that may eventually reach many tens of centimetres across.
Flowering:
September–July.
The small white capitula are approximately 4–6 mm across and are borne on slender peduncles above the foliage.
Its unusually long flowering season gives the species considerable ornamental value.
Fruiting:
September–August.
Mature cypselae are approximately 1 × 0.5 mm, pale brown, slightly compressed and transversely wrinkled.
Uses:
• Native groundcover
• Rock gardens
• Crevice planting
• Coastal gardens
• Banks Peninsula restoration
• Dryland native planting
• Low edging
• Between paving stones
• Botanical collections
• Conservation planting
Appearance:
Growth habit:
A creeping perennial herb forming open to diffuse mats or patches.
Growth originates from surface-running rhizomes, with several branches sometimes radiating from around flowering nodes early in the growing season.
Later-season branches are more often produced singly.
Leaves are usually clustered in groups of approximately 3–10 but may become more widely spaced during vigorous growth.
Short shoots are absent or poorly developed.
Rhizomes/Stems:
Rhizomes run at the soil surface and range from slender to relatively stout, approximately 0.5–2 mm in diameter.
Early in the season, up to five branches may arise around a flowering node.
Later branches usually develop singly.
Roots are approximately 0.5–1 mm thick, firm and leathery.
Flowering peduncles arise directly from the rhizomes and are slender, hairy and approximately 20–50 mm long.
They are usually equal to or longer than the leaves and either lack bracts or carry a single small bract.
Leaves:
Leaves are 1-pinnatifid and approximately 10–50 mm long by 3–10 mm wide.
The blade is approximately 3–40 mm long, obovate, leathery and more or less hairless.
Colour is dull green, with the lower pinnae commonly developing substantial brown pigmentation.
There are approximately 5–12 pairs of pinnae.
These are separated rather than overlapping and are divided completely to the rachis.
Each pinna is obovate and may carry up to seven teeth, although these are usually concentrated on the lower pinnae.
The teeth occur mainly on the outer margins and are cut approximately halfway to two-thirds across each pinna.
They are oblong, blunt and terminate in a minute point.
Flowers:
Flower heads are approximately 4–6 mm across with a convex surface and spreading involucre.
There are approximately 15–20 involucral bracts arranged in two roughly equal rows.
These bracts are almost circular, hairy and bordered by a broad brown papery margin.
Female florets number approximately 70–130 and are arranged in two or more rows.
They are about 1.75 mm long, straight and white, with equal corolla teeth.
Male florets are approximately equal in number.
Plants are monoecious, with both male and female florets occurring on the same individual.
Fruit:
The fruit is a small dry cypsela approximately 1 mm long and 0.5 mm wide.
It is slightly compressed and develops a pale brown colour at maturity.
The surface is marked by transverse wrinkles.
Seeds:
Each cypsela contains a single seed.
The light papery fruits are dispersed mainly by wind and may also be moved through incidental attachment to animals or other material.
Ecology:
Leptinella minor is a specialist of open, sparsely vegetated rocky ground.
Its creeping rhizomes allow it to spread across shallow soils and into small gaps between stones, while its low profile helps it withstand exposed coastal and hill-country conditions.
The species appears poorly competitive against dense taller vegetation and is most successful where rock, shallow soil or disturbance maintain open ground.
Introduced grasses and other weeds may threaten some populations by closing these gaps and shading the low-growing plants.
It is closely related to Leptinella filiformis and Leptinella nana.
From L. filiformis it differs in its generally larger and more robust habit, thicker rhizomes, longer leaves, more numerous teeth and larger flower heads.
From L. nana it is readily distinguished by its greater size, dull green foliage and white rather than differently coloured capitula.
Associated habitats:
Rock outcrops, rubbly slopes, skeletal soils, open grassland, coastal rocky ground, dry exposed banks and sparsely vegetated hill-country sites.
Associated vegetation is generally low and open, including native grasses, small herbs, lichens, mosses and other plants capable of surviving on shallow rocky soils.
How to grow:
Banks Peninsula button daisy is easy to cultivate when provided with suitable drainage.
Grow in full sun to partial shade in a fertile but sharply free-draining soil.
It performs especially well in rock gardens, crevices, raised beds and between stones where the foliage can spread without competition.
Full sun generally produces the most compact growth.
Avoid humid, poorly ventilated positions and prolonged waterlogging.
Once established, plants can spread steadily through creeping rhizomes and form attractive low mats.
Propagation:
Easily propagated by division of established plants.
Small rooted sections can be separated and replanted directly into free-draining soil.
Fresh seed also germinates readily when available.
Vegetative division is the quickest way to establish new plants and preserves selected forms exactly.
Cultural use:
No specific traditional Māori material use is well documented for Leptinella minor.
Its significance lies particularly in its status as a distinctive component of the indigenous flora of Banks Peninsula and as a remnant of vegetation that once extended onto the Canterbury Plains.
Garden value:
An attractive and useful native groundcover with finely divided foliage and a very long flowering season.
Its small white button-like flowers provide interest through much of the year, while the creeping habit makes it well suited to rock gardens, path edges, crevices and other open spaces.
It is particularly valuable in Banks Peninsula and Canterbury-themed native gardens where its local provenance and conservation significance can be highlighted.
Its compact growth, hardiness and tolerance of exposed conditions make it one of the more practical Leptinella species for cultivation.