Plumeless Thistle

Information

Carduus acanthoides - Asteraceae Family - Biennial

spiny_plumeless_thistle_1_tile spiny_plumeless_thistle_2_tile spiny_plumeless_thistle_3_tile spiny_plumeless_thistle_4_tile

Identification

Flowers: Flower heads are red-purple in color and can span up to 1 inch. Flower stems are branching with spiny wings extending to the flower head.
Seeds: Seeds are oblong, striated, and slightly curved. They are mainly wind-dispersed and can remain viable in the soil for up to 10 years. Plumeless Thistle spreads entirely by seed.
Leaves: The leaves of the basal rosette are 4-8 inches long and have spiny teeth. The stem leaves are alternate and attach directly to the stem. They are sparsely hairy underneath.
Flowering Time: June through August.
Life cycle: Plumeless Thistle is a biennial, meaning it produces a basal rosette in its first season with the stems and flowering bodies coming the season after. It flowers and disperses seeds from early to mid-summer.

Impacts

Plumeless Thistle is unpalatable to livestock and can greatly reduce an area’s forage potential if allowed to spread.
Thistle fragments and spines may injure livestock and humans moving through infestations.
Dense stands of thistles can greatly impede recreational activities, hinder grazing livestock, and obstruct wildlife from access to water.
Plumeless Thistle forms thick monocultures which can greatly reduce the biodiversity in an area.

Most effective control methods

Prior to flowering, small infestations can be effectively controlled by hand pulling or digging while being careful to ensure the removal of the entire root system. Mowing and cutting plants can also be effective if done prior to seed production.
Several herbicides are useful for managing this weed, if applied in the fall when the plants are in their seedling or rosette stage.

Plumeless thistle: flower

Plumeless thistle: rosette

Plumeless thistle

Plumeless thistle: foliage and flower

Plumeless thistle: stem and foliage

Plumeless thistle: seeds

Plumeless thistle: infestation

Plumeless thistle