Cotula coronopifolia L.
Common names: water buttons, button weeds, brass buttons (Eng.); gansgras, eendekos (Afr.).
Cotula coronopifolia is a cute yellow button daisy that is either annual or perennial, which occurs along edges of saline or freshwater pools, between late autumn and spring.
Cotula coronopifolia is a perennial or annual herb. Stems are decumbent, thick and spongy and can reach a maximum height of 300 mm. Leaves are alternate, either entire to apically trifid or regularly pinnate to bipinnate (found in the Namaqualand populations).
The leaf base is dilated which forms a prominent sheath around the stem; leaf sheath is between 4.0–6.0 mm long, either light to dark green or purplish, hairless.
Bracts has either 1 or 2 series; bracts are oblong to lanceolate. Flowerhead consists of 2 types of florets: a single series of female disciforms and inner series of yellow disc florets (ca. 35 to 50 per flowerhead).
Cotula coronopifolia is a common widespread species and there is no threat to cause this species to go extinct. As a result, this species is listed as Least Concern (LC).
Distribution and habitat
Cotula coronopifolia is found to be widespread in the Eastern, Northern and Western Cape. The species is also naturalized in isolated populations in Gauteng and in other parts of the world, such as North America, South America, Europe and Australia. C. coronopifolia grows in clumps on the margins of freshwater or saline pools, smaller individuals have been known to occur in waterlogged soils. Flowering time is mainly May to October (late autumn to spring).
Derivation of name and historical aspects
The genus Cotula has ± 55 species which are found mainly in southern Africa, with some species occurring in Australia, Central to South America with 2 species endemic to the Tristan da Cunha islands. The name Cotula comes from the Greek kotule, meaning ‘small cup’, which could be referring to the receptacle of the flowerheads of species in this genus. The name coronopifolia means ‘with leaves like Coronopus’, the former genus name of Lepidium, plants in the Brassicaceae known as swinecress or wartcress, and Coronopus means ‘crow’s foot’, referring to the shape of the leaf.
Seeds are mainly water dispersed and this is because of the species’ seeds being buoyant. It has also been noted that dispersal can be carried out by birds, but this type of dispersal is highly unlikely and if it does occur, it is rare.
Cotula coronopifolia has been used as a gold dye in North America and Europe. Horticulturally it is used as a decorative plant around a body of water, such as a pond. In Europe they are found to be in freshwater ponds in the cities.
Growing Cotula coronopifolia
Cotula coronopifolia can be propagated fairly easily from either seeds or cuttings and do not need any prior treatment. If propagating from a cutting, the cutting selected should be a piece of the stem that has roots occurring at the nodes. C. coronopifolia can tolerate a wide range of soils, but prefers moist soil, where large clusters of the species will develop. If smaller individuals of the species are desired, then waterlogged soil is ideal. They grow in full sun but can tolerate partial shade.
This species can be used as a garden plant as a feature next to a pond or water feature where the numerous bright yellow flowerheads will be a lovely contrast to the green colour of the leaves. This combination will be a stunning addition to any garden.
Cotula coronopifolia has no known pests or diseases.
- Lovas-Kiss, A., Sanchez, M.I., Wilkinson, D.M., Coughlan, N.E., Alves, J.A. & Green, A.J. 2019. Shorebirds as important vectors for plant dispersal in Europe. 2019. Ecography 42: 956–967.
- Manning, J. & Goldblatt, P. 2012. Plants of the Greater Cape Floristic Region 1: the Core Cape Flora. Strelitzia 29. South African National Biodiversity Institute, Pretoria.
- Noe, G. & Zedler, J.B. 2000. Differential effects of four abiotic factors on the germination of salt marsh annuals. American Journal of Botany 87(11): 1679–1692.
- Powell, R.F., Boatwright, J.S. & Magee, A.R. 2014. A taxonomic revision of the Cotula coronopifolia group (Asteraceae) and implications for the conservation statuses of the species. South African Journal of Botany 93: 105–117.
- Powell, R.F., Magee, A.R. & von Staden, L. 2013. Cotula coronopifolia L. National Assessment: Red List of South African plants version 2017.1. Accessed on 2020/02/03.
- Quattrocchi, U. 1999. CRC World Dictionary of plant names: common names, scientific names, eponyms, synonyms, and etymology. CRC Press, New York.
- Van der Toorn, J. 1980. On the ecology of Cotula coronopifolia L. and Ranunculus sceleratus L. Acta Botanica Neerlandica 29: 385–396.
- Windle, P. 1984. Technology, renewable resources, and American crafts: background papers. Congress of the United States, Office of Technology Assessment, Washington D.C.
Acknowledgements: the author thanks Dr Antony Magee and Dr Robyn Powell for their images.
Plant Type: Bi/Annual
SA Distribution: Eastern Cape, Gauteng, Northern Cape, Western Cape
Soil type: Sandy, Loam, Brack/saline
Flowering season: Spring, Autumn, Winter
Flower colour: Yellow
Aspect: Full Sun
Gardening skill: Easy