Taxonomic name: Acanthus mollis L.
Common names: acanto-grego (Portuguese-Brazil), Artist's acanthus (English), bear's breech (English), bear's breeches (English), oyster plant (English), sea-dock (English), sea-holly (English)
Organism type: herb
Acanthus mollis is a dicotyledon herb that has a tall inflorescence - up to 2 m high. It is cultivated for ornamental reasons and often grows in the wild as a garden escape. A. mollis is native to southern Europe, Morocco, Tunisia, Algeria, the Mediterranean islands, Turkey, Syria and the Canary Islands.
Acanthus mollis is a rhizomatous, perennial herb. It has upright stems that grow up to 1 m long and are hairless. Leaves are borne on petioles up to 50 cm long and are about 30 cm by 50 cm, hairless, and with deeply pinnate lobes that are acutely toothed The characteristic inflorescence, which can bring the total height of the A. mollis plant up to 2 m high, has white corollas with purple veins (3.5 - 5 cm long) and appears in summer.Seeds are foremd in dry capsules although most spread appears to be vegetative (Conn 2005; Stace et al. Undated a; Williams 2008).
coastland, natural forests, riparian zones, ruderal/disturbed, scrub/shrublands, urban areas
Acanthus mollis can grow in a variety of soil types, including clay, and those that are dry and sandy. It prefers light to medium soil types. It can grow in partial shade or full sun; and it is cold hardy and drought tolerant. A. mollis is frequently cultivated in gardens; it can be found growing on waste land, roadsides and railway banks. A. mollis has also been found in coastal areas, disturbed areas, forests, riparian zones, scrublands and urban areas (ARPS 2007-2012; NPPA undated; Stace et al. undated a).
Acanthus mollis can form dense infestations under forest canopies, which supresses growth and regeneration of native plants species. Although found only in natural ecosystems in Australia, it is thought that A. mollis could become an agricultural pest in several states (ARPS 2007-2012; Groves et al. 2003; NPPA 2008).
Acanthus mollis is grown as an ornamental due to its tall, striking inflorescence. A. mollis has also been used for medicinal purposes in the past (USDA-ARS 2010).
Acanthus mollis is listed in the FDA Poisonous Plant Database (McGuffin et al. 2000; NPPA 2008).
Native range: Algeria, Canary Islands, France, Italy, Malta, Morocco, Spain, Syria, Tunisia, Turkey, former Yugoslavia (USDA-ARS 2010).
Known introduced range: Australia, Brazil, Cyprus, New Zealand, Portugal, South Africa, United Kingdom, United States. (Biondi & Pedrosa-Macedo 2008; Della & Iatrou 1995; Domingues de Almeida & Freitas 2006; Foxcroft et al. 2007; Groves et al. 2003; Howell & Sawyer 2006; USDA-NRCS 2010).
Introduction pathways to new locations
For ornamental purposes:
Internet sales/postal services: Acanthus mollis seeds for sale online, for example in New Zealand on a internet auction/classified website, http://www.trademe.co.nz (Trade Me 2010).
Other: Acanthus mollis plants found to be growing in places where garden waste is dumped (Hosking et al. 2007).
Local dispersal methods
Garden escape/garden waste: Acanthus mollis plants often found to be growing in places where garden waste is dumped or near existing plants (Hosking et al. 2007).
Other (local): Spread of Acanthus mollis is likely be vegetative (Hosking et al. 2007)
Preliminary management has been carried out in Australia and New Zealand. In Australia, Acanthus mollis has been noted to require control measures in three or less locations, while it has been included in a list of species requiring research as part of a pest management plan in New Zealand. (ARPS 2007-2012; Groves et al. 2003).
Acanthus mollis reproduces by seed, which is spread via water currents, gravity and animals - seed setting occurs two years after germination. It can also reproduce via rhizomes, and vegetatively, via root fragments. (ARC 2008; Hosking et al. 2008; Williams 2008).
Reviewed by: Dr. Peter Williams, Landcare Research, Nelson
Compiled by: IUCN SSC Invasive Species Specialist Group (ISSG) with support from the Auckland Regional Council (ARC)
Last Modified: Monday, 1 November 2010