Phytolacca americana (pokeweed)

Phytolacca americana (pokeweed)
Large herb, up to 3 m, and quadrangular stems, frequently reddish, and with black berries.
Scientific name: Phytolacca americana L.
Common names: pokeweed, American pokeweed, pokeberry
Family: Phytolaccaceae
Status in Portugal: invasive species
Risk Assessment score: (in development)
Synonymy: Phytolacca decandra L., Phytolacca vulgaris Crantz
Last update: 11/07/2014
How to recognise it
Large herb up to 3 m, ramified, sometimes woody
on the base. Quadrangular stems, green, red or
purple.
Leaves: simple, with 12-25 x 5-10 cm, ovatelanceolate or ovate-elliptic.
Flowers: white or pink, with similar tepals,
forming a long raceme (up to 30 cm) ± erect, 10
stamens.
Fruits: purple-black berries, composed of 10
fused segments in a ring, making the stem hang
in maturation.
Flowering: May to December.
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Close-up of a flower raceme
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Phytolacca americana (pokeweed)
Similar species
Phytolacca heterotepala H. Walter, also exotic and normally found in the surroundings of Coimbra and
Lisbon, is similar but it is a shrub (or small shrub) and it presents unequal tepals (the exterior narrower
that the rest) and more stamens (9-21).
Characteristics that aid invasion
It propagates by seed, producing more seeds which are dispersed by birds.
It also propagates vegetatively by sprouts from the roots.
ORIGIN AND DISTRIBUTION
Native distribution area
North America.
Distribution in Portugal
Mainland Portugal (Minho, Trás-os-Montes,
Douro Litoral, Beira Litoral, Beira Alta, Beira
Baixa, Estremadura, Ribatejo, Alto Alentejo,
Algarve), Azores archipelago (all islands),
Madeira archipelago (Madeira island).
Other places where the species is invasive
Invasive in several European countries, western
USA (California).
Introduction reasons
For medicinal purposes and use in dyeing.
Preferential invasion environments
Ruderal and disturbed habitats, crop fields and roadsides. It also invades semi-natural habitats.
IMPACTS
Impacts on ecosystems
It inhibits the development of native vegetation.
It has allelopathic effects, obstructing the development of other species.
Economic impacts
It causes important damages in agricultural areas.
Other impacts
Some parts of the plant (stems, leaves, fruits) are toxic, being noxious for animals.
CONTROL
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Phytolacca americana (pokeweed)
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 Phytolacca americana include:
Physical control
Hand pulling (preferential methodology). In more compacted substrates, hand pulling must be made
during the rainy as to facilitate the removal of the root system. As much as possible, it should be
guaranteed that there are no large roots left in the ground.
Chemical control
Foliar application of herbicide. Spray with herbicide (active substance: glyphosate, 2,4-D) limiting its
application to the target species.
For additional information, visit the webpage www.invasoras.pt and/or contact us at [email protected].
REFERENCES
DAISIE European Invasive Alien Species Gateway (2012) Phytolacca americana. Available: http://www.europe-aliens.org/
speciesFactsheet.do?speciesId=8642 [Retrieved 10/11/2012].
Dufour-Dror J-M (2012) Alien invasive plants in Israel. The Middle East Nature Conservation Promotion Association, Ahva,
Jerusalem, 213pp.
Fagundes D, Az J, Beiras MB (2007) Bioloxía, distribución e métodos de control. Xunta de Galicia, Santiago de Compostela,
209pp.
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.
Silva L, Corvelo R, Moura M, Land EO, Jardim R (2008) Phytolacca americana L. 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. 370-372.
USDA, NRCS. (2012) The PLANTS Database. National Plant Data Team, Greensboro, NC 27401-4901 USA. Available: http://
plants.usda.gov [Retrieved 10/11/2012].
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