Bull thistle – Cirsium vulgare

Bull thistle

Cirsium vulgare (Savi) Tenore
Asteraceae (Aster family)

Life cycle

Erect, spiny biennial.

Leaves

First-year leaves originate from a basal rosette, followed by an erect, branched, flowering stem in the second year. Seedlings have egg- to spatula-shaped cotyledons and oval, oblong to spatula-shaped leaves with bumpy surfaces and marginal spines. Mature leaves are alternate, lance-shaped, deeply cut or lobed, with long, stiff spines. Leaves have coarse hairs above and soft, cottony hairs below.

Stems

Spiny-winged, hairy stems elongate during the second year, often branched up to 7 feet tall.

Flowers and fruit

Red to purple, usually solitary flower heads consisting of only disk flowers are 1 to 2 inches wide and encircled by spine-tipped bracts. The seed is enclosed in a single-seeded, chili- pepper-shaped, wind-disseminated fruit.

Reproduction

Seeds.

Similar weeds

Canada thistle [C. arvense (L.) Scop.]
Differs by having a prolific, patch-forming perennial nature with a deep, creeping root system; leaves with smooth, dark green upper leaf surfaces and irregularly lobed to crinkled, spiny margins; and smaller (less than 1 inch wide) pink to purple flower heads with spineless bracts.

Bull-thistle-flower-300x266
Bull thistle flower
Bull-thistle-leaf-300x240
Bull thistle leaf
Bull-thistle-leaf-surface-300x240
Bull thistle leaf surface
Bull-thistle-rosette-300x199
Bull thistle rosette
Bull-thistle-seedling-300x200
Bull thistle seedling

For more information visit:

Plant & Pest Diagnostics

Other Documents in this Series

Michigan State University Michigan State University Close Menu button Menu and Search button Open Close