Appearance

Growth form

A coarse, bushy summer annual about 2–4 ft (0.6–1.2 m) tall, with a stout taproot. The thick, rough stems often have purple to black spots.

Leaves

Large and triangular to heart-shaped, with 3–5 irregular lobes, coarse teeth, and long stalks. Both sides feel like sandpaper.

Flowers

Small greenish flowers at the branch tips and leaf joints. Flowering starts in summer as the days get shorter.

Fruit

An oval, brown, woody bur ½–1 in (1.3–2.5 cm) long, covered with hooked prickles, with two beaks at the tip. Each bur holds two seeds, and one plant can make more than 2,000 burs.

Look-alikes

Where it lives

Typical habitats

• crop fields
• pastures
• roadsides
• ditches
• riverbanks

Range

Widespread across North America, and naturalized in many other parts of the world.

Preferred conditions

Favors moist, disturbed ground.

Life cycle

Seed dispersal

Burs hitch rides on fur and clothing, and they float, so they also travel along waterways. Seeds can stay dormant in the soil for years.

Cautions

Cautions

Seeds and young seedlings are highly toxic to livestock and can be fatal. Livestock usually avoid the grown plant. People have also been poisoned after eating the seedlings.

Connected species

Ties with other wildlife

In Missouri, finches, ground squirrels, and mice eat the seeds despite their toxicity, and leaf beetles, leafminer flies, stem borers, and aphids feed on the plant.

Pollinators

Wind-pollinated, so it doesn't draw bees or butterflies.

Name and classification

About the name

Botanists disagree on where cocklebur first came from: some think North America, others Central or South America. Several forms are treated as subspecies of this one broad species, while some countries, such as Japan, treat a few of them as separate species.

Conservation

IUCN Red List

NENot Evaluated·Not yet assessed