Argemone mexicana: Mexican poppy

Family: Papaveraceae
Common name: Mexican poppy, Mexican prickly poppy, Flowering thistle, Devil’s fig, Yellow poppy, Mexican thistle, White thistle, Golden thistle of Peru, Caro, Cardosanto

It is difficult to miss this bluish-green, beautiful, but extremely prickly Mexican poppy plants growing in open areas and disturbed soil. The plant grows to a height of 2-3 feet with thorns on most surfaces. Stem of the Mexican poppy plant is also bluish-green with thin, short hairs and thorns.

Upper surface of the leaves are blue-green with white venation, and lower surface is light green. Deeply lobed leaves have very pointy thorns of different sizes with white borders. Leaves have no stalk, the lower lobes straddling the stem, and are about 5-7 inches long. Leaves are tightly packed at the base of the plant, making it almost impossible to weed them with naked hands.

Mexican poppy flowers are very beautiful, yellow and cup-shaped. They could be creamy white or bright yellow and about 1-2 inches in diameter. The flowers have 6 delicate petals and prominent stamens. Considering how prickly and dangerous the plant looks, the flowers are beautifully delicate, attached to the tips of the stem with no stalk. The sepals and petals drop away as the flowers mature into fruits.

Mexican prickly poppy fruits are covered with thorns, ellipsoid, about 1-1.5 inches long. They are thick in the middle and narrow towards the ends. When the seeds mature, the fruits split from top to bottom releasing small mustard-like rounded seeds. In tropical weather, the plant is capable of flowering and reproducing almost throughout the year, making it a noxious weed.

The plants are drought-tolerant and can grow in any kind of soil. They are very bothersome in agricultural farms, where these plants choke growing seedlings of crop plants. Weeding is the best possible method to remove these weeds, but they cannot be done by hand. The plants contain a yellow latex in almost all parts, which is poisonous to humans and animals. That, and the prickly thorns make sure that grazing animals do not touch Mexican poppy plants.

The seeds contain Argemone oil, which if used to adulterate vegetable oils, can make them poisonous. There are also reported instances of poisoning where Mexican poppy seeds were mixed with mustard seeds, since both look alike.

In spite of the poisonous latex, the plant has traditionally been used as a medicine for kidney ailments, malaria, skin conditions, snake and scorpion bites, worm infections, cough, cold, asthma, respiratory ailments, jaundice and for improving eyesight. The seeds were used as laxative, and the leaves were used to make herbal tea. The oil obtained from seeds is used for making soap, and also applied to wood to protect them from termites.

Propagation is through seeds.

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