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Montana Field Guide

Montana Field Guides

Rough Cocklebur - Xanthium strumarium

Native Species

Global Rank: G5
State Rank: SNA

Agency Status
MNPS Threat Rank:
C-value: 3

External Links

General Description
Stems erect, strigose, 10–100 cm, . Leaf blades cordate-deltate, 2–12 cm long, serrate, sometimes shallowly few-lobed, sparsely short-hispid. Burs 2–4 cm long, 2-beaked, stipitate-glandular (Lesica 2012. Manual of Montana Vascular Plants. BRIT Press. Fort Worth, TX).

Our plants are variety canadense (Mill.) Torr.& A.Gray

Diagnostic Characteristics
Xanthium strumarium is distinguished from spiny clotbur (X. spinosum) by its broader cockleburs, more ovoid leaves on long petioles, and lack of spines.

Species Range

Range Comments
Xanthium strumarium is distributed worldwide (53 degrees north to 33 degrees south latitude) but is most common in the temperate zone (Love and Dansereau 1959). It is a serious weed in Australia, India, South Africa, and the Americas.

There has been considerable controversy regarding the origin of cocklebur. Though first described from Europe, it is probably of American origin (Munz and Keck 1973). Love and Dansereau (1959) suggest that the cocklebur subspecies most abundant in North America (cavanilliesii) originated in Central America. The dates of its introduction to California are not known, but it may be pre-Columbian.

Observations in Montana Natural Heritage Program Database
Number of Observations: 78

(Click on the following maps and charts to see full sized version) Map Help and Descriptions
Relative Density



(Observations spanning multiple months or years are excluded from time charts)

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Citation for data on this website:
Rough Cocklebur — Xanthium strumarium.  Montana Field Guide.  .  Retrieved on , from