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© Sandy Wolkenberg

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Inclusion in Plant ID / Comparison Guides

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collage of Field Thistle and Bull Thistle

Field Thistle (Cirsium discolor) vs. Bull Thistle (Cirsium vulgare)

Updated March 8th, 2023

These species are visually similar and are easily confused where their ranges overlap. They are easily distinguished by involucres (cluster of bracts under each flowerhead) and the color of leaf undersides, and also by stems and sometimes by flower color. Cirsium discolor is more restricted to mesic conditions whereas Cirsium vulgare ranges much farther west and north, ranges into both moister and drier sites, and is more tolerant of rocky soils. Both can be found in disturbed habitats but C. discolor also occurs in higher-quality natural areas.

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