Cutleave Teasel - Dipsacus laciniatus

Habit: Biennial; monocarpic; grows 2-6 ft tall; stout taproot; first year plant a basal rosette of wrinkled leaves.

Leaves: Stem leaves lance-shaped and irregular, deeply pinnately-cut, opposite, joined at bases surround the stem in a cup-like appearance.

Stems: 3 m tall, with hooked and straight prickles; striate ridged, herbaceous but stout, erect, typically single from the base, branching in the apical half.

Flowers: White to purple in color, 4-parted, with irregular petals; inflorescence a dense, cylindrical cluster on a long, naked stalk, spiny bracts not taller than the flower cluster; blooms July through September.

Fruit and seeds: Each flower is replaced by an oblong seed that is 4-angled, truncate on one end and rounded on the other, plants can produce up to 2000 seeds viable for at least 2 years.

Habitat: Native to Europe. Grows in moist soils and found along roadsides and in disturbed areas.

Reproduction: By seed.

Similar species: Fuller's teasel (Dipsacus fullonum); Wild lettuce (Lactuca spp.) when in rosette stage, quite different once flowering stalk forms.

Monitoring and rapid response: Hand-pulling and digging for small infestations; Frequent mowing throughout growing season; effectively controlled using any of several readily available general use herbicides.

For additional information - https://extension.illinois.edu/invasives/invasive-teasels