Mexican Pricklypoppy

Argemone mexicana

mexican pricklypoppy

Mexican pricklypoppy, photographed at Fort Zachary Taylor State Park, Key West, Monroe County, in April 2017.

Mexican pricklypoppy, Argemone mexicana, stands out with its large, showy yellow flowers and silver green leaves with prominent white veins. It looks like someone crossed a dandelion with a prickly pear.

The leaves are deeply and sharply lobed with spines on the end. It also produces spikey seed capsules, seen to the right of the flower in the feature photo on this page. The flowers are large and bright yellow, somewhat similar to prickly pear.

The U.S. Department of Agriculture's PLANTS Database classifies Mexican pricklypoppy as native to North America. But other sources say it's questionably native to Florida and even more questionably native to most of the eastern U.S. A species is considered native if it was present at the time the first Europeans arrived in the New World. Some argue that it is an import to Florida and probably the rest of its North American range, which extends as far north as Manitoba and Ontario. If it is an import, it's not clear how it got here.

The Lady Bird Johnson Wildflower Center says Mexican Pricklypoppy is native as far north Viriginia and naturalized in higher latitudes. Flora of North America says its probably native to South Florida but likely an escapee from cultivation north of here.

Its probably native to the Caribbean, Mexico, Central America and South America, although some question South America. It's taken up home in Africa, India, China and Australia. It's a significant agricultural pest in Kenya, Uganda and Tanzania. South Africa and several states in Australia classify it as a noxious weed.

It is an annual, found in sandy soil and full sun, and blooms year-round in South Florida. It's found in disturbed areas such as fallow fields and roadsides, which is where we first found this plant. We've also seen it growing in Fort Zachary Taylor State Park, where the feature photo on this page was taken.

Mexican pricklypoppy is used for a variety of remedies, but all parts of the plant are toxic. According to the Flora of Pakistan, the seeds have narcotic properties. It supposedly has a soothing effect on headaches when used externally. It's also used externally on a variety of skin conditions, including herpes. It is used to treat abnormal collection of fluids; an oil made from the seeds is used to treat ulcers — and as a fuel for lamps.

It can be giant pain in the butt for farmers. It can outcompete crops, and it makes harvesting a painful ordeal not only because of the prickles but because of chemicals it possesses that can irritate the skin. Mexican pricklypoppy infestations in pasturelands are problematic because livestock won't touch it. It is a large seed producer, but the majority will fall near the parent plant. Some will be carried away by rainwater runoff, some will be picked up by animals, boots and mechanical equipment. Birds also will help disperse the seeds. Mexican pricklypoppy also produces allelopathic chemicals, which inhibit the seeds of other species from germinating. It's problem when the seeds are the next crop. Oddly enough, despite the problems it causes, Mexican pricklypoppy is often grown to improve soil conditions.

Other names include goatweed, Mexican poppy, devil's fig, yellow-flower thistle, Mexican thistle, golden thistle of Peru, prickly poppy, Mexican prickly poppy, medicinal weed and others. It is a member of Papaveraceae, the poppy family.

Click on photo for larger image

U.S. Department of Agriculture Distribution Maps

Published by Wild South Florida, PO Box 7241, Delray Beach, FL 33482.

Photographs by David Sedore. Photographs are property of the publishers and may not be used without permission.