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A. mexicana is an annual herb, up to 150 cm tall with a slightly branched tap root. The stem is erect, branched, usually prickly, pale bluish-green and exudes an unpleasant-smelling yellow sap when cut. Leaves are alternate, without petioles, more or less sheathing the stem, up to 15 cm long, deeply lobed with irregularly toothed, spiny margins;greyish-white veins are conspicuous on the bluish-green upper surface of the leaves. Flowers are solitary, 2.5-4.5 cm in diameter, subtended by 1-2 leafy bracts;sepals 3, prickly;petals 4-6, yellow to pale orange, glabrous;stamens numerous. Fruit is a capsule, spiny, 2.5-5 cm long and 2 cm wide, with 4-6 valves opening at the tip to release numerous seeds. Seeds are brownish-black, nearly spherical, about 1 mm in diameter, covered in a fine network of veins, oily.
A. mexicana forma leiocarpa is a form found in West Africa which has few or no prickles on the stem, leaves and capsule (Lucas, 1962).

Related invasive species

  • Argemone mexicana

Related Farm Practice

  • Hosts
  • Release
  • Cropping systems
Impact

A. mexicana is a widespread annual weed primarily associated with agricultural crops and wastelands. It is a major weed of a number of crops in the tropics and warm temperate regions and is persistent as it produces a seed bank. In India in particular, the species is a health hazard and because of its prickliness, is a nuisance to subsistence farmers. In South Africa the seeds of A. mexicana have been declared as 'noxious' as its seeds or bits of seeds may represent a hazard to human or animal health when consumed (NDA, 2001). It is reported as invasive in many countries in Asia, Africa, the Caribbean and Americas, and Oceania (Australia and a number of Pacific island states).

Has Cabi datasheet ID
6878
Hosts

A. mexicana is a weed of most cropping systems, including large- and small-grain cereals, legumes, vegetables, fibre crops (cotton, sisal) and perennial crops (coffee, sugarcane). It appears that any crop has the potential to be infested with A. mexicana if grown within the habitat range of this weed.

Oss tagged
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