How to recognise it
Flowers: arranged in pedunculate capitula of 5-10 mm diameter, with yellow internal flowers (of the disk) shortly pedicellate, hermaphrodite, tubular; external flowers with long pedicels, without corolla; ovate involucral bracts, and a scarious margin.
Flowering: March to September.
Although it’s not easy to confuse Cotula coronopifolia, Tanacetum vulgare L. (common tansy) has capitula that are somewhat similar, but the plant is taller, the leaves have deep indentations, and since it is not salt intolerant it tends to occur in different habitats.
Characteristics that aid invasion
It propagates by seed producing many seeds that are dispersed by water, and able to travel hundreds of meters per year. The seeds are viable for 1 or 2 years.
It also propagates vegetatively, through stem fragments that have great rooting ability.
Native distribution area
South Africa (Cape region).
Distribution in Portugal
Mainland Portugal (Minho, Douro Litoral, Beira Litoral, Estremadura, Ribatejo, Baixo Alentejo, Algarve).
Geographic areas where there are records of Cotula coronopifolia
Europe (Spain), western USA (California), Australia.
Preferential invasion environments
It develops in humid areas, even where salinity is high; normally seen along the beaches, tide zones and estuaries. It also occurs in rice fields.
The species has adapted to several types of soils, being able to grow in acid, basic and neutral soils.
It doesn’t tolerate shade nor frost.
Impacts on ecossystems
It forms continuous mats that inhibit the development of native vegetation.
Potentiallyit may reduce productivity in rice fields.
– Atlantic salt meadows (Glauco-Puccinellietalia maritimae) (1330);
– Mediterranean salt meadows (Juncatalia maritimi) (1410).
Controlling an invasive species demands a well-planned management, which includes the determination of the invaded area, identifying the causes of invasion, assessing the impacts, defining the intervention priorities, selecting the adequate control methodologies and their application. Afterwards it is fundamental to monitor the efficiency of the methodologies and recuperation of the intervened area as to perform, whenever necessary, the follow-up control.
The control methodologies used for Cotula coronopifolia include:
Physical control (preferencial methodology)
Hand pulling: it is applied to plants of all sizes. It should be done before fruit maturation and it should be guaranteed that no roots and/or large fragments remain in the soil.
Although the application of herbicides is referred to as one of the most efficient methodologies to control the species, there is no information about its application in Portugal.
Visit the webpage How to Control for additional and more detailed information about the correct application of these methodologies.
Marchante E, Freitas H, Marchante H (2008) Guia prático para a identificação de plantas invasoras de Portugal Continental. Imprensa da Universidade de Coimbra, Coimbra, 183pp.