Chatham Island Button Daisy
Botanical name: Leptinella featherstonii
Synonyms: Cotula featherstonii, Cotula renwickii
Common name(s): Chatham Island button daisy, Mutton bird plant
About:
Leptinella featherstonii is a remarkable endemic Chatham Islands daisy and one of the most unusual members of its genus because of its large, robust, woody to subwoody shrub habit.
Unlike the creeping or mat-forming growth typical of many Leptinella, this species can develop into a leafy shrub up to approximately 1.5 m tall and 2 m wide. Its thick stems, fleshy grey-green to dark green leaves and compact button-like flower heads are adaptations to exposed, nutrient-rich coastal environments.
It has a particularly strong ecological association with seabird colonies. Many of its best populations occur on predator-free offshore islands and rock stacks where nesting seabirds continually enrich the soil with nutrients and create the open, disturbed conditions in which the plant thrives.
Natural habitat:
Coastal peaty ground, seabird nesting areas, exposed offshore islands, rock stacks and nutrient-rich coastal crevices.
It is most commonly associated with burrowing or nesting seabirds.
On some offshore islands it can become extremely abundant and may even dominate the vegetation.
On Western Reef it also grows in rock crevices enriched by nutrients deposited by seals and non-burrowing seabirds.
Growing environment:
Full Sun, Coastal Exposure, Wind, Salt-laden Air, Cool Climate, Nutrient-rich Soil, Peaty Soil & Open Conditions tolerant.
It favours cool maritime environments with good airflow and soils enriched by seabird or marine-derived nutrients.
Although adapted to exposed coastal conditions, it dislikes prolonged drought and can also suffer in warm, humid conditions.
Plants may collapse suddenly when subjected to environmental stress, even after appearing well established.
Endemic distribution:
Endemic to the Chatham Islands.
Formerly widespread throughout the archipelago.
On Rēkohu/Chatham Island it now survives principally at Kaingaroa and near Ocean Bay.
It also occurs on several offshore islands, reefs and rock stacks including Rangatira/South East Island, Little Mangere Island, the Pyramid, Motuhara/Forty-Fours, Star Keys, the Sisters, Western Reef and the Murumuru rock stacks near Rangihaute/Pitt Island.
Height:
Usually approximately 0.2–1.2 m tall, occasionally reaching around 1.5 m.
Width:
Can spread to approximately 2 m across in well-developed plants.
Flowering:
Primarily spring and summer, with flowering potentially extending into autumn under suitable conditions.
Flower heads are approximately 8–10 mm across and contain numerous cream, white, yellow, yellow-green or green florets.
Fruiting:
Primarily late summer and autumn.
Mature cypselae are approximately 1.5 × 0.7 mm, dark chocolate-brown to almost black and conspicuously pale-ribbed.
Uses:
• Chatham Islands conservation planting
• Specialist coastal gardens
• Seabird-island restoration
• Botanical collections
• Ex-situ conservation
• Wildlife habitat planting
• Coastal shrub borders
• Educational collections
• Chatham Islands-themed gardens
• Naturalistic maritime planting
Appearance:
Growth habit:
A robust, leafy, perennial shrub or subshrub with an unusual woody to subwoody habit for the genus.
Plants are monoecious, bearing both female and male florets on the same individual.
One to many stems arise from the base. They are initially erect but often become spreading with age and may occasionally become decumbent.
Branches commonly arise in clusters of three or four, occasionally as many as six, around flowering nodes.
Leaves are densely crowded toward actively growing branch tips, while older leaves or their persistent bases remain spaced along older stems.
Trunk/Bark:
A conventional woody trunk is usually absent, but mature stems become distinctly woody or subwoody toward the base.
Stems may reach approximately 20 mm in diameter.
Young growth is fleshy and succulent, green to orange-green and smooth to finely hairy.
Older stems become heavily marked by persistent leaf scars, giving them a strongly textured appearance.
Branches that contact the ground can occasionally produce adventitious roots.
Leaves:
Leaves are simple, almost stalkless and approximately 15–60 mm long by 6–25 mm wide.
The blade is broadly obovate and gradually narrows toward an indistinct petiole.
Texture varies from somewhat membranous under favourable conditions to distinctly fleshy and crisp in exposed sites.
Colour ranges from grey-green and glaucous to yellow-green or dark green.
Leaves are usually covered in fine, soft, velvety hairs when young, although these hairs often become sparse or disappear as the leaf matures.
The midrib and major veins are generally visible on both surfaces.
The leaf margin may be completely entire or bear up to three shallow, blunt triangular teeth or lobes near the apex.
Flowers:
Flowers are grouped into hemispherical button-like capitula approximately 10 mm across.
Flowering peduncles are approximately 5–20 mm long, shorter than the leaves and finely hairy. They may be without bracts or carry one or two small leaf-like bracts immediately below the flower head.
Each capitulum is surrounded by approximately 10–18 broadly elliptic involucral bracts arranged in one or two unequal rows.
These bracts are fleshy, green and marked by one to three brown veins, with a narrow transparent papery margin near the apex.
Female florets are numerous, often around 200 per head, and arranged in approximately six or more rows.
They are around 2 mm long and may be white, cream, yellow, yellow-green or green.
Male florets are somewhat fewer, commonly up to approximately 130 per head.
Fruit:
The fruit is a dry cypsela approximately 1.5 mm long and 0.7 mm wide.
It is slightly compressed and does not become wrinkled at maturity.
Colour ranges from chocolate-brown to black.
The surface is conspicuously marked by pale ribs, including two lateral ribs and several additional ribs on the front and rear surfaces.
Seeds:
Each cypsela contains a single seed.
The small papery fruits are dispersed principally by wind and possibly through incidental attachment to birds, animals or other moving material.
Its close association with seabird colonies may also assist local movement of fruits amongst disturbed coastal vegetation.
Ecology:
Leptinella featherstonii is closely tied to the ecology of Chatham Islands seabird colonies.
Seabirds transport large quantities of marine-derived nutrients onto land through guano, discarded food and carcasses, maintaining highly fertile soils that support the species’ unusually luxuriant growth.
Burrowing and nesting also continually disturb the ground, suppressing dense competing vegetation and creating open sites suitable for establishment.
On predator-free offshore islands where seabird populations remain abundant, mutton bird plant can become locally dominant.
Its decline on parts of Rēkohu/Chatham Island reflects disruption of this ecological relationship as well as direct habitat loss.
Threats there include coastal erosion, invasive weeds, browsing mammals, reduced seabird activity, declining soil fertility, storm damage, invertebrate attack and inappropriate collection.
Associated habitats:
Seabird nesting colonies, coastal peatlands, open maritime shrubland, cliff tops, offshore islands, rock stacks and nutrient-rich coastal rock crevices.
Associated vegetation can include other Chatham Islands coastal herbs and shrubs, along with specialised plants adapted to highly fertile, wind-exposed seabird environments.
How to grow:
Chatham Island button daisy is a specialist plant that can be difficult to maintain over the long term.
Grow in full sun in a cool, well-ventilated position with a maritime or coastal climate.
A fertile, humus-rich soil with good drainage but reliable moisture is preferable.
The plant requires more nutrients than many native alpine or coastal species, reflecting its natural association with heavily enriched seabird soils.
Avoid prolonged drought, but equally avoid stagnant water and warm, humid conditions.
Air circulation is especially important.
Even established plants may collapse suddenly after drought, excessive humidity or other environmental stress, so consistent growing conditions are preferable.
Propagation:
Can be propagated from fresh seed and cuttings.
Fresh seed should be sown onto a free-draining, fertile medium and kept consistently moist without becoming waterlogged.
Cuttings taken from healthy actively growing shoots can also be rooted.
Although propagation itself is achievable, maintaining mature plants in cultivation can be considerably more difficult.
Young plants should be gradually acclimatised to exposed conditions and protected from prolonged drought or excessive humidity.
Wild plants should not be removed.
Cultural use:
The common name mutton bird plant reflects the species’ strong association with seabird breeding colonies.
Detailed traditional Moriori or Māori material uses are not widely documented.
Its close relationship with seabird islands nevertheless makes it a particularly characteristic plant of the Chatham Islands maritime environment and an important component of the archipelago’s natural heritage.
Garden value:
An exceptional and highly distinctive native plant for specialist coastal and botanical collections.
Its robust shrubby habit, succulent grey-green foliage and numerous pale button-like flower heads give it a character quite unlike the smaller creeping Leptinella species.
It is especially valuable in Chatham Islands displays, maritime gardens and conservation collections.
Its ecological relationship with seabird colonies also makes it an excellent educational species for illustrating the profound influence marine birds can have on island vegetation.
Because of its sensitivity to drought, humidity and other stress, it is best suited to experienced growers able to provide cool, exposed, reliably moist conditions.