REPORT

Invasive Plant Details

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Plumeless Thistle

Latin Name: Carduus acanthoides

Priority Ranking: Regional EDRR

Identification

Flower: Small, purple, thistle-like flower heads that bloom from midsummer to fall.

Leaves: Deeply lobed, spiny, and dark green.

Stems: Erect, spiny, and branching, growing up to 1.5 meters tall.

Growing Environment: Prefers well-drained soils in pastures, fields, and disturbed areas.

Growth Habit: A biennial herb that forms a basal rosette in its first year and a tall, spiny flowering stalk in its second year. It spreads via seeds and forms dense thickets of spiny plants. In situ, plumeless thistle appears as dense, spiny stands with purple flowers, often in disturbed areas.

Priority Ranking: Regional EDRR

Impacts on Environment

Impacts: Highly invasive in pastures and disturbed areas, where it forms dense, spiny stands that outcompete native vegetation.