EPPO Global Database

EPPO Reporting Service no. 01 - 2009 Num. article: 2009/016

The situation of Alternanthera pungens in the EPPO region


Alternanthera pungens (Amaranthaceae) is a prostrate herb considered as a weed.

Geographical distribution
EPPO region: Spain.
Africa: South Africa.
Asia: India.
North America: USA (Alabama, Florida, Georgia, Hawaii, New York, South Carolina, Texas, Virginia).
Central America and Caribbean: Puerto Rico.
South America (native): Brazil, Ecuador, Peru, Venezuela.
Oceania: Australia (and listed as a regulated weed in New South Wales, Northern Territory, South Australia, Victoria and Western Australia), New Caledonia, New Zealand, Papua New Guinea.

Note: Within the EPPO region, the species is naturalized in Spain, it colonizes citrus orchards and summer crops in the East of Spain, but is not regarded as an important weed (J Recasens, pers. comm. 2009). In Israel, the species was recorded in the Northern Negev in wet places and was mentioned as “very rare (casual)”by Zohary in 1966. It has not been found in Israel since this record (A. Danin, pers. comm., 2008). In Belgium, the species was introduced as a wool contaminant in 1949 but did not naturalize (Verloove, 2006).

Morphology
A. pungens has a perennial root system and its taproot is often large and woody. Leaves are opposite, ovate to circular, 2-4 cm long and 0.5-1.5 cm wide with a short petiole. Stems have silky hairs and are up to 60 cm long. Flowers are very small, white, and surrounded by spiny bracts. Fruits are prickly burrs of 1-1.5 mm long and seeds are yellowish, glabrous and about 1-2 mm wide. Local spread occurs through the rooting of stems at the nodes, and seeds are spread within spiny bracts that adhere to tyres, clothing and animals.

Habitats
The species grows in grasslands and disturbed places, orchards, summer crops, and prefers sandy soils.

Impacts
A. pungens is considered to be a weed of warm temperate and tropical areas around the world. The plant quickly colonizes bare or disturbed ground and once established, it forms dense and persisting infestations that exclude almost all other vegetation and prevent the regeneration of native species. Aboveground, stems die back during autumn and new shoots grow each spring. The species is considered a “weed”, “quarantine weed”, and “noxious weed” by the Global Compendium of weeds. Additionally, spines are a problem for dogs and stock but are particularly troublesome to humans as they penetrate skin.

This species could spread within the Mediterranean area of the EPPO region, but it does not seem to present a major risk. Therefore, the EPPO Secretariat decided not to include it in the EPPO Alert List.

Sources

A Global Compendium of Weeds.
http://www.hear.org/gcw/alpha_select_gcw.htm
Delivering Invasive Alien Species Inventories for Europe (DAISIE) Database. http://www.europe-aliens.org/
New Zealand Plant Conservation Network. http://www.nzpcn.org.nz/exotic_plant_life_and_weeds/index02.asp?FilterStatus=5&Filter=a
Pacific Islands Ecosystems at Risk (PIER) Website – Alternanthera pungens
http://www.hear.org/Pier/species/alternanthera_pungens.htm
Tutin et al. (1964-1980) Flora Europaea. 5 Vol. Cambridge University Press. http://rbg-web2.rbge.org.uk/FE/fe.html
Verloove F (2006) Catalogue of the Neophytes in Belgium (1800-2005). Scripta Botanica Belgica 39, p 89
Weber, E (2003) Invasive Plant Species of the World. CABI Publishing Wallingford, (GB) pp. 41.
Weeds Australia Website. http://www.weeds.org.au/
Zohary M (1966) Flora Palaestina part 1. The Israel Academy of Sciences and Humanities, Goldberg’s Press. P. 364.