Xanthium strumarium L.

Family: Asteraceae, Tribe: Heliantheae

Pertinent Synonyms & Notes (particularly those used in California; go to GRIN for other synonyms)

including ssp. canadense (Mill.) Torrey & A. Gray and many other infraspecific taxa

Pertinent Common Names (particularly those used in California; go to GRIN for other common names)

common cocklebur

Primary Disseminule Type

spiny bur

Description (diagnostics are in brown)

Disseminule a spiny bur consisting of a hardened receptacle tightly enclosing two cypselae.

Bur ellipsoid, brown, 10–35 mm long x 8–20 mm diameter, with numerous spines, two chambers and a pair of conspicuous thick, straight or curved beaks (4–6 mm long) at apex. Spines stout, ca. 3–6 mm long, ± straight and then hooked at tip, lower portion often stiff glandular-hairy or sometimes minutely glandular to glabrous.

Similar Species

Xanthium spinosum

Risk Assessment (codes in yellow or red indicate cause for concern; assessments are current as of mid-2011; click AUQP, NZBORIC, or NZBPI for access to the most recent versions of these databases and possible assessment changes)