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weed with prickly seed pod

It is distinguished by its tall, stout, branched stem (like small trees), large leaves, large, white or purplish trumpet-shaped flowers, large spiny seedpod and sour repulsive odour.

Cotyledons (seed leaves) are narrow and about 2-4cm long, shriveling but persisting on the developing seedling. The first true leaves are ovate with pointed tips and few or no lobes. Later leaves distinctly alternate (1 per node), usually somewhat coarsely and sharply toothed or lobed, 10-20cm long and long-stalked.

All parts of the plant are poisonous.

Toxicity

Stems stout, erect, 90-200cm high, usually much-branched in the upper part, smooth and hairless. Larger plants will have a main stem often 5cm or more in diameter.

Jimsonweed occurs in the warmer parts of southern Ontario in cultivated fields and around farmyards.

Flowers and seedpods short-stalked, borne singly in the angles between 2 or more stems and a leaf. The calyx is tubular or urn-shaped. The corolla is white or light purple, very long, tubular or trumpet-shaped, 7-10cm long with the flared end having 5 points. The seedpod is at first green and fleshy with sharp, soft spines, becoming a large (2-5cm across), dry, hard seedpod covered with very sharp, harsh spines and containing numerous black, flat, round seeds. Flowers from July to autumn.

All parts of the jimsonweed plant are poisonous and are fatal if consumed in high quantities. Its toxicity is caused by tropane alkaloids.

Therefore, you may want to use an old woolen blanket to drag over the area first, which should snag most of these burrs. Then the area can be treated with a pre-emergent, such as corn gluten meal, to prevent germination of any seeds left behind. Late summer or early fall is a good time to do this.

Burr medic germinates in fall and winter, and flowers in spring.

Once burr medic has been eradicated, you’ll want to improve the health of your soil to minimize its return by amending it with organic matter or compost.

Types of Burr Weeds

You can recognize this weed by its green serrated leaves and reddish purple colored stems that creep closely along the ground. It also has small yellow flowers. After flowering, the tiny green pods produce prickly burrs. These will eventually dry up and turn brown, spreading seeds everywhere.

The use of broadleaf post-emergent weed killer, like Weed-B-Gone, prior to flowering (winter/early spring) can help as well.

Other burr species include:

While burr medic can be controlled with regular mowing, this will not kill the weed. It is also tolerant of most herbicides, though non-selective types can help kill the plant as well as boiling water. Neither of these, however, will kill the burrs that are left behind in the lawn or garden.

The Weed of the Month series explores the ecology and history of the common wild plants that most gardeners consider weeds.

The genus name Datura comes from the Hindi word for the plant, noteworthy since most botanical names are derived from Latin or Greek. The origins of the plant itself are contested—every source I checked listed a different native origin, ranging from Mexico to India, and it now grows all over the world. Not surprisingly, it has found its way into many cultural and medicinal traditions. Ayurveda, traditional Chinese medicine, and Native American shamanistic practices all employ jimson weed medicinally or ritualistically. Its seeds and leaves are used as an antiasthmatic, antispasmodic, hypnotic, and narcotic.

The Weed of the Month series explores the ecology and history of the common wild plants that most gardeners consider weeds.

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Having grown up in Virginia, I was intrigued by one of the common names I saw recurring in my plant books—Jamestown weed—and researched the origins. One story simply connects the first New World observations of the plant to settlers in this early Virginia colony. A more famous tale tells of the plant’s accidental ingestion by some British soldiers sent there to suppress Bacon’s Rebellion in 1676. After eating some in a stew, the soldiers spent 11 days in a hallucinatory stupor, blowing feathers, kissing and pawing their companions, and making faces and grinning “like monkey[s].”

Though the trumpet-shaped flowers are stunning, my favorite part of the plant is the devilish-looking seedpod. The size of a Ping-Pong ball and covered in spikes, the seed capsule splits into four parts like a monster’s maw, revealing the dark brown seeds inside. In the winter you might notice its tall, dry stalks bearing the prickly seedpods, which to me look like the scepter for a demon. With all its extraordinary looks and lore, jimson weed is a fascinating plant to contemplate (but maybe not cultivate)!

Jimson weed’s white to purple blooms are fragrant at night, attracting moths and other nocturnal pollinators, a common trait in white-bloomed plants. The rest of the plant, however, is stinky! Crush and sniff the oaklike leaves, and you’ll understand why domesticated and wild animals avoid eating this plant—it smells a bit like feet. Indeed, accidental poisonings tend be more common among humans than among other animals.

Jimson weed (Datura stramonium) is a beautiful, witchy plant that begins blooming in late summer and continues through the first frost. A member of the notorious nightshade family, its more famous cousins include tomato, eggplant, pepper, tobacco, and potato. Most members of this plant family are poisonous, and jimson weed is no exception. All parts of the plant are toxic, most particularly the seeds. Potent amounts of alkaloid compounds are present, which potentially cause convulsions, hallucinations, and even death if ingested. And as climate change increases the amount of carbon dioxide in the air, studies have found that the toxicity of plants like jimson weed only increases.