Perennial herb, frequently creeping and fragile, with small white or pink flowers that looks like a small daisy.
Scientific name: Erigeron karvinskianus DC.
Common names: Karwinsky’s fleabane, daisy fleabane, daisy, Latin American fleabane, Mexican daisy, seasurface daisy
Family: Asteraceae (Compositae)
Status in Portugal: invasive species (listed in the annex I of Decreto-Lei n° 565/99, of 21 December)
Risk Assessment score: (in development)
Synonymy: Erigeron mucronatus DC.
Last update: 11/07/2014
How to recognise it
Perennial herb of 15-50 cm, ramified, sub-ligneous on the base and a fragile look.
Flowers: arranged in small capitula (with less than 1 cm diameter) with thin and long peduncles (3-8 cm); marginal ligulate flowers, hairlike, white or pink on the upper and purple on the lower surface; yellow flower disks.
Flowering: February to September.
There are several similar species of “white and yellow daisies”. However, E. karvinskianushas smaller capitula than most other species. One of the most similar species is Bellis annua L. (annual daisy), which is annual with only 5-12 cm, normally leaves that are broader and cypselas without pappus.
Characteristics that aid invasion
It propagates by seed producing many seeds, which are easily dispersed by the wind.
It also propagates vegetatively from rhizomes.
Native distribution area
Mexico and tropical South America.
Distribution in Portugal
Mainland Portugal (Minho, Trás-os-Montes, Douro Litoral, Beira Alta, Beira Baixa, Beira Litoral, Estremadura, Ribatejo, Alto Alentejo), Azores archipelago (all islands), Madeira archipelago (Madeira island).
Other places where the species is invasive
Europe (Spain), New Zealand, western USA (California).
For ornamental reasons, continuing to be grown in gardens.
Preferential invasion environments
Rupicolous habitat: walls, cracks on rocks and cobblestones; it also grows next to gardened spaces, frequently disturbed, from where it was planted.
Species with an invasive behaviour, mainly in the north of the country.
Impacts on ecossystems
It forms continuous mats that smother of native species when competing for space, water and nutrients.
Natura 2000 Network habitats more subject to impacts
– Calcareous rocky slopes with chasmophytic vegetation (8210);
– Siliceous rocky slopes with chasmophitic vegetation (8220).
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 Erigeron karvinskianus include:
Hand pulling: preferential methodology. It should be done before fruit maturation. In more compacted substrates, hand pulling should be done in the rainy season as to facilitate the removal of the entire root system. It should be guaranteed that no roots remain in the soil.
Foliar application of herbicide. Spray with herbicide (active principle: glyphosate) limiting the exposure as much as possible to the target species.
Visit the webpage How to Control for additional and more detailed information about the correct application of these methodologies.
Betancort JAR, Guerra AS, Silva L, Carvalho JA (2008) Erigeron karvinskianus R. Br. In: Silva L, Land EO, Luengo JLR (eds) Flora e fauna terrestre invasora na Macaronésia. Top 100 nos Açores, Madeira e Canárias. Arena, Ponta Delgada, pp. 275-278.
Global Invasive Species Database (2012) Erigeron karvinskianus. Available: http://www.issg.org/database/species/ecology.asp?si=1278&fr=1&sts=&lang=EN [Retrieved 10/11/2012].
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.
Weedbuster (2012) Erigeron karvinskianus. Available: http://weedbusters.co.nz/weed_info/detail.asp?WeedID=21 [Retrieved 10/11/2012].
This post is also available in: Portuguese (Portugal)