Common Teasel
Dipsacus fullonum
Washington State Classification
Class C — Widespread, County-Selected Control
It has been a common weed of roadsides and other disturbed areas and recently has begun to invade valuable agricultural lands in Washington.
Quick Reference
Identification
Growth Habit
Common teasel is a taprooted, monocarpic plant that grows as a biennial or short-lived perennial that dies after it flowers. They develop a stout, fleshy taproot in the rosette stage that can be more than 2 feet long and 1 inch in diameter at the crown.
Leaves
Basal leaves are oblanceolate with wavy margins and typically die early in the second season. Leaves have spines on the underside of the midvein and smaller spines on bases on the upper leaf surface. The stem leaves are opposite and prickly, especially on the lower side of the leaf midvein.
Flowers
Dense flowerheads, up to 4 inches tall, occur individually at the tips of leafless flower stems and opposite side branches. Bracts at its base are linear, more or less prickly, curved upward and unequal in length. Flowers bloom in 2 rings and are generally pale purple to dark pink.
Fruit & Seeds
Fruits are dry achenes and about 0.12 to 0.31 inches (3-8 mm) long and typically have 8 pale ribs.
Impact
It has been a common weed of roadsides and other disturbed areas and recently has begun to invade valuable agricultural lands in Washington. Due to the present management practice of mowing old seedheads, seedheads that contain viable seed are being spread along roadways and into various habitats.
Ecology & Spread
Habitat
It escapes cultivation and grows in garden areas, along creeks, pond edges, roadsides, abandoned fields and other disturbed sites. It is also grows into agricultural areas, fallow fields, pasture lands and hay meadows. It prefers open, sunny habitats and can survive in a range of wet to dry conditions. Please click here to see a county level distribution map of common teasel in Washington.
Spread Mechanisms
Reproduction
It reproduces from seed. A single flowerhead can on average produce around 850 seeds and plants typically produce 1 40 flowerheads. Seeds can be dispersed by floating on water, in mud, soil movement, human activities and by animals and birds.
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Control Methods
Mechanical
- Rosettes can be dug up, though it is important to remove as much of the root as possible to prevent resprouting. Flowering stalks can be cut from plants where flowering has already initiated and not before or stems will resprout. Cut flower stalks should be removed from the area.
Biological Control
- There are currently no biological control agents available for common teasel.