Subshrub with whitish tomentose leaves and flashy yellow flowers.
Scientific name: Senecio bicolor (Willd.) Tod. subsp. cineraria (DC.) Chater.
Common names: dusty miller, silver ragwort
Family: Asteraceae (Compositae)
Status in Portugal: invasive species (listed in the Decreto-Lei nº 92/2019, de 10 july)
Risk Assessment score: 19 | Value obtained according to a protocol adapted from the Australian Weed Risk Assessment (Pheloung et al. 1999), by Morais et al. (2017), according to which values above 13 mean that the species has risk of having invasive behavior in the Portuguese territory | Updated on 30/09/2017.
Synonymy: Senecio cineraria DC.
Last update: 11/07/2021
How to recognise it
Woody subshrub up to 50 cm, with white tomentose stems.
Leaves: from 4-5 x 2,5-7 cm, ovate to lanceolate, dentate to pinnatisect, white-tomentose in the lower surface, ± tomentose, greenish to glabrescent on the upper surface.
Flowers: yellow, arranged in capitula with12-15 mm diameter, arranged in dense corymbs, with white-tomentose bracts.
Fruits: cypselas with white hairs.
Flowering: May to July.
Characteristics that aid invasion
It propagates by seed and its seeds are wind-dispersed.
It also propagates vegetatively, by stem sprouts.
Native distribution area
Central and Oriental Mediterranean region.
Distribution in Portugal
Mainland Portugal (Minho, Douro Litoral, Beira Baixa, Beira Litoral, Estremadura).
Geographic areas where there are records of Senecio bicolor subsp. cineraria
Other places where the species is invasive
Western USA (California).
Probably for ornamental purposes.
Preferential invasion environments
Subspontaneous in beach areas and several rocky littoral locations.
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 Senecio bicolor include:
Hand pulling: applied to plants of all sizes. Because it is a frequent species in sandy substrates, hand pulling is normally easy. On rocky areas, hand pulling should be done carefully as to avoid release of the rocky substrate.
Visit the webpage How to Control for additional and more detailed information about the correct application of this methodology.
DAISIE European invasive">Invasive Alien species">Species Gateway (2012) Senecio cineraria. Available: http://www.europe-aliens.org/speciesFactsheet.do?speciesId=23608 [Retrieved 10/11/2012].
Gallastegui MH, Prieto JAC (2010) Flora alóctona invasora en Bizkaia. Instituto para la Sostenibilidad de Bizkaia, Vizkaya, 196pp.
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.
USDA, NRCS. (2012) The PLANTS Database. National Plant Data Team, Greensboro, NC 27401-4901 USA. Available: http://plants.usda.gov [Retrieved 10/11/2012].