Yellow Buttons

Botanical name: Cotula coronopifolia
Synonyms: None
Common name(s): Yellow Buttons, Bachelor’s Button, Water Buttons, Brass Buttons, Buttonweed

About:
Yellow buttons is a low-growing wetland herb with creeping stems, fleshy leaves and bright yellow button-like flower heads. Although native to southern Africa, it is now widely naturalised in New Zealand and occurs in damp, muddy and saline habitats. Its tolerance of brackish water and waterlogged soils makes it especially suited to coastal wetlands, salt marshes and ephemeral waterways.

Natural habitat:
Muddy wetland margins, coastal salt marshes, estuaries, damp hollows, ephemeral waterways, swales, brackish seepages and wet disturbed ground.

Growing environment:
Prefers full sun and moist to wet soils. Tolerates waterlogging, brackish water, saline soils, coastal exposure and periodic inundation.

Endemic distribution:
Not endemic to New Zealand. Native to southern Africa and naturalised in New Zealand and many other temperate regions of the world.

Height:
5–30 cm

Width:
20–60 cm or more by creeping stems

Flowering:
Spring–summer

Fruiting:
Summer–autumn

Uses:
• Wetland margins
• Swales and ephemeral waterways
• Coastal wetland planting
• Pond edges
• Ornamental ground cover in damp sites
• Habitat planting for wetland insects

Appearance:
Growth habit:
A somewhat fleshy, creeping to ascending perennial or short-lived herb. Stems branch from the base, creep along the ground, root at the nodes and then rise to produce leaves and flower heads.

Leaves:
Leaves are fleshy, glossy and bright green, often with reddish stems. They may be narrow-oblong to lance-shaped and entire, or irregularly divided into several lobes. The leaf bases often clasp the stem.

Flowers:
Flower heads are bright yellow, rounded and button-like, usually 8–10 mm across. They are borne singly on slender stalks from the leaf axils or stem tips.

Fruit:
The fruit are small corky cypselae with broad spongy wings that allow them to float and disperse by water.

Ecology:
Seeds are dispersed by water, allowing the plant to spread through wetland systems and along waterways. The species occupies a specialised niche in muddy, anoxic and saline environments where many less tolerant plants struggle to grow.

Associated habitats:
Coastal salt marsh, estuarine wetlands, wet swales, pond margins, brackish seepages, ephemeral waterways and damp disturbed ground.

How to grow:
Plant in full sun in wet or seasonally damp soil. It is best suited to sites that remain moist or are periodically flooded. It can tolerate brackish water and coastal conditions but may spread where conditions are favourable.

Propagation:
Propagates readily from seed and rooted stem fragments. Creeping stems root at the nodes and can be divided or transplanted into suitable wet sites.

Cultural use:
Historically, the plant has been used as a source of yellow dye in some regions. In modern landscapes it is mainly valued as an ornamental wetland ground cover.

Garden value:
A useful small wetland plant for pond edges, swales and coastal damp sites, valued for its bright yellow button flowers and tolerance of wet, saline conditions. It is best used where its creeping habit can be managed.