Bull Thistle — Cirsium vulgare — Family: Asteraceae — Aster
Bull thistle is a clumping biennial that forms a thick taproot in its first growing season. The leaves of bull thistle are covered with 'soft' hairs and needle-like spines on the margin. Leaves of seedlings are not deeply lobed like mature leaves. This is the thistle you stepped on in your bare feet as a kid. Bull thistle will form an erect branched habit in its second season on which the large purple blossoms will form if left unmowed.
Oter weeds in the Aster (Asteraceae) family:
Bull thistle is a clumping biennial that forms a thick taproot in its first growing season. The leaves of bull thistle are covered with 'soft' hairs and needle-like spines on the margin. Leaves of seedlings are not deeply lobed like mature leaves. This is the thistle you stepped on in your bare feet as a kid. Bull thistle will form an erect branched habit in its second season on which the large purple blossoms will form if left unmowed.
Also Known As...
- spear thistle
- bur thistle
- plume thistle
- roadside thistle
- Cardus vulgare
- Cirsium lanceolatum
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Elongated |
Notches |
Clump |
bushy clump of deeply-lobed, hairy leaves with spiny margins
large purple solitary flower head produced on erect stalks during second growing season
thick fleshy taproot formed in first year
Bull thistle, a biennial, is often confused with Canada thistle but can be distinguished by the profuse hairs present on the upper leaf surface. Bull thistle will often appear as a single specimen, whereas Canada thistle will almost always be present with several daughter plants.
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Bull thistle is associated with low maintenance areas and roadsides. Because bull thistle is a biennial it relies on reproduction by seed. Plants that establish during renovation will persist for up to two seasons. Consistent mowing and good nitrogen fertilization will likely create a turf that resists infestation from a second generation.
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