Woolly Distaff Thistle
Carthamus lanatus
Washington State Classification
Monitor List
This plant is on the monitor list.
Quick Reference
Identification
Growth Habit
Woolly distaff thistle is an erect annual that grows up to 3.3 feet tall and has a long, slender taproot.
Leaves
Plants begin as a rosette of leaves that often wither by when its in flower. Stem leaves are alternate, sessile (without petioles), stiff and spreading outward to slightly curved downward and pinnately lobed. Leaf lobes spine-tipped.
Flowers
Flowerheads of woolly distaff thistle are solitary, at stem tips and composed of many yellow flowers. Bracts at the base of flowerheads are spine-tipped. Flowerheads are mostly 25-35 mm long.
Fruit & Seeds
Achenes are broader at the tip than the base and have a lateral notch near the base. Color varys from buff to brown and may have dark brown mottling. Achenes from the outer part of the flowerheads are rough and may lack a pappus. Inner achenes are smoother and have a papus of narrow, unequal brownish scales. The pappus is mostly 10-13 mm long.
Impact
This plant is on the monitor list. Please contact the Washington State Noxious Weed Control Board to report locations or for more information.
Ecology & Spread
Habitat
Plants grow in open disturbed areas including roadsides, agricultural land, fields and pastures.
Spread Mechanisms
Reproduction
Woolly distaff thistle reproduces by seed.
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