PLUMELESS THISTLE

(Carduus acanthoides L.)

COMMON NAMES:

Spiny plumeless thistle

DESCRIPTION:

Plumeless thistle is a winter annual or a biennial plant that originated from Eurasia. This plant tends to be shorter than any other invasive thistles and can generally reach 1 to 4 feet tall. The first year Plumeless thistle does not bloom, but when it flowers it shows a spiny winged stems that completely extend up and down the stem unlike Musk thistle. The stems are winged and more branched that gives the plant and candelabrum appearance. The flowers are small and range from .5-1 inch in diameter but very numerous and pink to purple in color or very rarely white-yellowish. The bracts beneath the flowers are very narrow and resemble spines. The heads can be singular or in cluster of 2 to 5. This plant flowers from May to August. Plumeless thistle can become very weedy and form dense colonies.

KEY FEATURES OF PLUMELESS THISTLE:

Plumeless thistle rosettes have wavy leaves with yellow spines along with white-colored leaf margins. Has a taproot and the seeds are inside the spiny flowers.

HABITAT:

Plumeless thistle can be found in cultivated fields, pastures, right-of-ways, rangeland, and non-cropped areas.

CONTROL:

There are herbicides and other control methods that commonly control plumeless thistle. For more information on these herbicides and other control methods contact the SCWP office.

OTHER FACTS:

Plumeless thistle is an important plant for the butterflies and the seeds are eaten by numerous species of songbirds. It may accumulate nitrates, but is unpalatable to livestock so they will not get poisoned by this plant.