cocklebur

Cocklebur refers to several species in the genus Xanthium, especially Xanthium strumarium (common cocklebur) and Xanthium spinosum (spiny cocklebur). They are annual herbs in the Asteraceae. Plants grow erect to about 0.5–2 meters, with rough, variably lobed leaves. Flowers are small and inconspicuous; male and female flowers occur in separate heads on the same plant. After flowering, a spiny bur forms, about 1–3 centimeters across, usually containing two seeds. The burrs cling to fur or clothing and aid dispersal.

Native to the Americas, cockleburs have become cosmopolitan weeds in temperate regions. They favor disturbed sites such as fields, roadsides, waste places, and riverbanks. They germinate in spring, and seeds typically mature by late summer. Seeds can remain viable in soil for several years, and dispersal is aided by the hooked spines and by human activity and equipment.

Cocklebur seeds contain carboxyatractyloside, a hepatotoxic glycoside. Ingestion by livestock or accidental human consumption can cause liver damage; contact with burrs is not common but should be avoided. Because of toxicity, handling burs requires care and contaminated feed should be discarded.

Control relies on preventing seed production and removing plants before burrs form. Mechanical methods (hand pulling, mowing), crop competition, and cleaning equipment help reduce spread. Chemical control may involve pre-emergent or post-emergent herbicides as part of an integrated weed-management plan that minimizes disturbance and seed rain.