Cotula coronopifolia aka Brass Buttons

Cotula coronopifolia is in the daisy family, Asteraceae. Gardeners call it brass buttons or buttonweed. Its home range runs from Angola to southern Africa. It grows in temperate zones, where the climate is mild. It is not native to Britain or Ireland. Kew calls it an annual or subshrub, a small woody plant. The RHS calls it an annual or short-lived perennial. It may thus live one year or last several years. Its life span does not follow one fixed pattern.

This low plant creeps across the ground and forms mats. The RHS says it grows about 0.8 feet [0.25 metres] tall. Its wider garden height range is 0.3–1.6 feet [0.1–0.5 metres]. Its listed spread is also 0.3–1.6 feet [0.1–0.5 metres]. These ranges allow for plants larger than the short account suggests. The leaves have a scent, and the plant sheds them. Some leaves are simple, with one blade. Others are pinnatifid, with deep cuts that form lobes.

Yellow flower heads rise above the creeping growth in summer. The RHS names summer but gives no exact months. It says to remove dead flower heads on a routine basis. It also lists the plant for use in wildlife gardens. Its low, spreading shape suits the damp sites it names. These sites are pond edges and moist borders.

Grow this plant in full sun and keep it moist. The RHS includes soil that drains poorly among suitable conditions. The plant accepts clay, loam and sand, a broad soil range. It can grow in acid, neutral or alkaline soil. Both open sites and spots with shelter suit it. The RHS names sites that face south or west. Its UK hardiness rating is H4. This covers lows of around 14–23°F [−10 to −5°C]. The rating applies to UK growing conditions, not all climates.

The RHS lists this plant as needing little care. It reports few usual pest or disease problems. Growers can raise it from seed or divide it in spring. The profile gives two to five years to reach full size. It gives no account of fruit for this species. Nor does it cover food use or toxic effects. These gaps do not mean the plant is edible or safe to eat.