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Ricinus communis

Shrub or small tree up to 5 m tall, with often reddish stems, large leaves with a star-like appearance and thorny fruits, reddish at maturity.

Scientific name: Ricinus communis L.

Common name: castor bean, castor; castor oil, castoroil plant, castor-oil plant, palma christi

Family: Euphorbiaceae

Status in Portugal: Invasive species (listed in Decree-Law no. 92/2019, 10 July)

Risk Assessment Score: 22 | 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: Ricinus africanus Willd., Ricinus angulatus Thunb., Ricinus armatus Haw., Ricinus badius Rchb., Ricinus chinensis Thunb., Ricinus digitatus Noronha, Ricinus europaeus T.Nees, Ricinus glaucus Hoffmanns., Ricinus hybridus Besser, Ricinus inermis Mill., Ricinus japonicus T hunb., Ricinus laevis DC., Ricinus leucocarpus Bertol., Ricinus lividus Jacq., Ricinus macrophyllus Bertol., Ricinus medicus Forssk., Ricinus megalospermus Delile, Ricinus minor Mill., Ricinus nanus Balbis, Ricinus peltatus Noronha, Ricinus purpurascens Bertol., Ricinus rugosus Mill., Ricinus sanguineus Groenland, Ricinus scaber Bertol. ex Moris, Ricinus speciosus Burm.f., Ricinus spectabilis Blume, Ricinus tunisensis Desf., Ricinus undulatus Besser, Ricinus urens Mill., Ricinus viridis Willd., Ricinus vulgaris Mill.

Last update: 27/06/2020

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Family: 
Euphorbiaceae
Appearence: 
Trees and shrubs

How to recognize it

Shrub or small tree up to 5 m, with hollow, reddish, and glabrous stems.

Leaves: alternate, 10-35 cm Ø, palmatipartite with 5-9 lobes, with irregularly serrated margin, long petiole, reddish.

Flowers: unisexual flowers gathered in large inflorescences at the ends of the stems. The female flowers are greenish or reddish, and are located closer to the tip, while the male flowers are greenish-yellow with cream-colored stamens, located at the base of the inflorescence.

Fruits: ovoid capsules, ± 2 cm long, reddish or greenish, covered with spikes, with 3 cavities containing 1 to 3 shiny seeds, brown in color, with white streaks and a small caruncle, resembling small ticks.

Flowering: it can flower throughout the year with maximum flowering from May to July.

 
Similar species
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Characteristics that aid invasion

It can flower and produce seeds throughout the year in frost-free places. It reproduces seminally, producing a high number of seeds (each plant can produce up to 150,000 seeds) that are easily dispersed by water and animals (rodents, ants, birds) and human activities. After drying the capsules release seeds that can be projected over great distances, creating new foci of invasion. The seeds can remain viable for 2 or 3 years, being reported in some studies that in certain situations it does not form a seed bank. Its seeds are among the first to germinate after fire.

 

Native distribution area

Tropical Africa.

Distribution in Portugal

Mainand Portugal (Trás-os-Montes, Douro Litoral, Estremadura, Alto Alentejo, Baixo Alentejo, and Algarve), in the Azores (all islands), and on Madeira archipelago (Madeira, Porto Santo, and Desertas islands).

For more detailed locations of this species, check the online interactive map. This map is still incomplete – we need your help! Contribute by submitting records of the location of the species where you can find it.

 

Geographical areas where there is a record of Ricinus communis 

 

 

Other places where the species is invasive

Australia, New Zealand, North America (EUA, Mexico), South America (Chile, Galápagos islands), Souhern Europe (France), Africa (Tanzania, Namibia, Botswana), Asia (China).

Introduction reasons

For food, medicinal and industrial purposes (to obtain castor oil). Former use as an ornamental is likely.

Preferential invasion environments

Very common species in disturbed, ruderal areas, such as roadsides and rubble. It also invades stream banks as well as natural and semi-natural areas (e.g. coastal dunes).

 

Impacts on ecosystems

Rapid growth leads to the formation of dense impenetrable areas that can impede the development of native vegetation.

Economic impacts

Potentially high costs in applying control measures.

Other impacts

The seeds are highly toxic, especially to humans and horses. Contact with the seeds can cause severe allergic reactions.

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 Ricinus communis include:

Physical control

Hand pulling: is one of the preferred methods. In more compacted substrates, the pulling should be carried out in the rainy season in order to facilitate the removal of the root system. It must be ensured that no larger roots remain in the soil.

Physical + chemical control

Cut combined with herbicide application: the stems should be cut as close to the ground as possible and then herbicide should be applied (active ingredient: glyphosate or triclopyr) in the cutting area. It should be carried out before the ripening of the fruits and only in situations where the use of herbicide cannot be avoided.

Chemical control

Foliar application of herbicide. Spray with herbicide (active ingredient: glyphosate) limiting the application to the target species. It should be carried out at the time of greatest plant growth and only in situations where the use of herbicide cannot be avoided.

Basal bark application of herbicide: herbicide shlould be applied at the base of the plant (active ingredient: tryclopir). It should be applied in a very localized way to young plants with a diameter greater than 5 cm.

Controlled fire

Controlled fire can be used in areas where large mats form. However, it renders better results in combination with other methods (eg to control formed seedlings) as it is referred to as being a good colonizer of newly burned areas.

Visit the webpage How to Control for additional and more detailed information about the correct application of these methodologies.

Burrascano C (2000) Ricinus communis. In: Bossard CC, Randall JM, Hoshovsky MC invasive">Invasive Plants of California’s Wildlands. University of California Press, Berkeley, CA.  pp. 269-273.

CABI (2014) Ricinus communis. In: invasive">Invasive species">Species Compendium. CAB International, Wallingford, UK. Disponível: www.cabi.org/isc [Retrieved 16/11/2014].

California invasive">Invasive Plant Council. Ricinus communis. Disponível: http://www.cal-ipc.org/plants/profile/ricinus_communis-profile/ [Retrieved 18/11/2017].

Global invasive">Invasive species">Species Database (2006) Ricinus communis. Disponível: http://www.issg.org/database/species/ecology.asp?si=1000&fr=1&sts=&lang=EN  [Retrieved 18/11/2017].

Instituto Hórus de Desenvolvimento e Conservação Ambiental. Ricinus communis. Disponível: http://www.institutohorus.org.br/ [Retrieved 18/11/2014].

Land EO, Coello RM, Carvalho JA, Silva L (2008) Ricinus communis 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. 382-384.

Marchante H, Morais M, Freitas H, Marchante E (2014) Guia prático para a identificação de Plantas Invasoras em Portugal. Coimbra. Imprensa da Universidade de Coimbra. 207 pp.

Morais MC, Marchante E, Marchante H (2017) Big troubles are already here: risk assessment protocol shows high risk of many alien plants present in Portugal. Journal for Nature Conservation 35: 1–12

Northern Territory Government (2014) Castor oil plant. Ricinus communis. [Retrieved 18/11/2014].

Pheloung PC, Williams PA, Halloy SR (1999) A weed risk assessment model for use as a biosecurity tool evaluating plant introductions. Journal of Environmental Management. 57: 239-251.

Sanz-Elorza M, Sánchez EDD, Vesperina ES (2004) Atlas de las plantas alóctonas invasoras en España. Dirección General para la Biodiversidade, Madrid, 384pp.

Weber E (2003) invasive">Invasive plant species of the world: a reference guide to environmental weeds. Reino Unido: CABI, 2003. ISBN 0851996957. 360pp.