Cotula coronopifolia, commonly known as Brass Buttons or Water Buttons, boasts a rich historical legacy as it was once utilized for its gold dye properties in both North America and Europe. Beyond its historical significance, this versatile plant has found a niche in horticulture, where it is cherished as an ornamental gem, especially near water bodies. The plant’s popularity is notable in European cities, where it is frequently cultivated around freshwater ponds for its aesthetic appeal.
The distinctive features of Cotula coronopifolia contribute to its allure. The bright yellow discoid flower heads, reminiscent of thick buttons, create a visually striking contrast against the lush greenery of its leaves. Originating from New Zealand and South Africa, this plant has successfully spread its vibrant presence to diverse regions, encompassing Europe, North America, and South America. While Brass Buttons is recognized for its invasive tendencies, its rate of spread is relatively gradual, earning it a “limited” invasive rating in California. The plant has been a familiar presence in the British Isles since the late 1800s, particularly along the Cheshire coast, where it has become a naturalized neophyte.
Adaptability is a key strength of Brass Buttons, as it thrives in challenging environments such as muddy, anoxic wetlands and saline conditions. Its salt tolerance is exemplified by the presence of fleshy leaves that store water, ensuring survival during periods of saline inundation. This unique trait allows the plant to carve out a niche along coastal areas, salt marshes, and estuaries.
Despite its annual or short-lived perennial nature, Cotula coronopifolia contributes to its own dispersal through buoyant seeds, which are carried by water. Functioning as a low-growing, mat-forming herbaceous plant, it graces gardens and natural landscapes with its small yet vibrant bright yellow flowers, creating a captivating and picturesque addition to these environments during the summer months.
Ideal for unmown swales and ephemeral waterways. Naturally found in Coastal Salt Marshes in plant communities that include but are not limited to Coprosma propinqua, Plaginathus divaricatus, Austroderia richardii, Juncus krausii, Shoenoplectus tabernaemontani, and Samolus repens. For more information on plant communities, we recommend the Department of Conservation’s booklet Plant Communities of the Canterbury Plains.