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Taxon  Report  
Cirsium arvense  (L.) Scop.
Canada thistle
Cirsium arvense is a perennial herb that is not native to California.
Cal-IPC rating: moderate
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Observation Search
~3112 records in California
redone or more occurrences
within a 7.5-minute quadrangle

Bloom Period
Genus: Cirsium
Family: Asteraceae  
Category: angiosperm  
PLANTS group:Dicot
Jepson eFlora section: eudicot

Arid West: Occurs usually in non wetlands, occasionally in wetlands
Mountains, Valleys and Coast: Equally likely to occur in wetlands and non wetlands

Communities: wetland-riparian

Name Status:
Accepted by JEF + PLANTS

Alternate Names:
PLANTSBreea arvensis
PLANTSBreea incana
PLANTSCarduus arvensis
PLANTSCirsium arvense var. argenteum
PLANTSCirsium arvense var. horridum
Information about  Cirsium arvense from other sources

[Cal-IPC] Invasive: Cirsium arvense (Canada thistle) is a perennial (family Asteraceae) found scattered throughout California, except in the Sonoran and Mojave Deserts and the southern Sierra Nevada. Canada thistle forms dense patches which may crowd out native vegetation. This clump-forming plant reproduces by seed and vegetatively from its extensive root system. Control is difficult because root fragments as small as 1 cm can sprout to form a new plant, and seeds are dispersed by small animals, wind and human activities. Occasional cultivation may increase Canada thistle populations by dispersing root fragments, but control can be achieved with continued cultivation, mowing or hand-cutting. Cal-IPC Rating: Moderate (link added by Mary Ann Machi)

[Wikipedia] Europe, Asia, Africa native: Cirsium arvense is a perennial species of flowering plant in the family Asteraceae, native throughout Europe and western Asia, northern Africa and widely introduced elsewhere. (link added by Mary Ann Machi)

Suggested Citation
Calflora: Information on California plants for education, research and conservation, with data contributed by public and private institutions and individuals. [web application]. 2024. Berkeley, California: The Calflora Database [a non-profit organization]. Available: https://www.calflora.org/   (Accessed: 07/18/2024).