Species distinguishing characteristics:
- Reddish-purple flowers with 5 petals
- Bur-like, teardrop-shaped seeds stick to fur and clothing
- Soft-hairy rosette of leaves in the first year
- Predominantly blue flowers (sometimes pink, purple, yellow, or white) with 5 flaring lobes
- Coiled flowering stalk, like a scorpion’s tail, with flowers blooming on the upper surface and lower flowers opening first
- Rough hairs usually covers foliage
- Leaves alternate, simple, and entire
- Fruit consists of 4 nutlets (occasionally fewer)
Biennial, or short-lived perennial, 1–4 feet tall. Produces a rosette during the first year and a flowering stem during the second year. Introduced from Europe.
Leaves and stems:
Erect, hairy stem that is branched near the top. Produces a single flowering stem, or multiple flowering stems, per plant. Rough-hairy leaves are 1–12 inches long and 1–3 inches wide. Leaves have entire margins. Alternate leaves on flowering stem.
Reddish-purple flowers in terminal branches with 5 petals that unite at the base.
Fruit has 4 prickly, flattened, bur-like nutlets (seeds) that are green when immature and are roughly the size of a corn kernel. Seeds turn brown and become adhesive when mature, readily clinging to clothing or animals. Mature plants can produce hundreds of seeds per year and are viable for 2–3 years. “Hitchhiking” seeds can easily spread great distances from their source.
Shade tolerant plant. Open forests and meadows, along roads and trails, and disturbed areas.
Contains toxic alkaloids that cause liver cells to stop reproducing. Also contains a compound called allantoin that may treat ulcers in the intestine and on the skin. Can be readily controlled by hand pulling and by avoiding seed dispersal.