Weed class: C
Year Listed: 2013
Native to: Northern Africa, Asia, Europe
Why Is It a Noxious Weed?
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.
How would I identify it?
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.
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.
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.
The second year flower stems grow 0.5-2 meters tall, are striate-angled and increasingly prickly going upward. Stems are pithy or hollow and have opposite branching.
Fruit Seed Description
Fruits are dry achenes and about 0.12 to 0.31 inches (3-8 mm) long and typically have 8 pale ribs.
May Be Confused With
Two other similar looking species of Dipsacus have been introduced into North America, D. laciniatus (cutleaf teasel) and D. sativus (cultivated teasel). D. laciniatus has irregularly-cut pinnatifid leaves and white flowers. D. sativus mainly differs by the awns of the bracts on the receptacle being shorter, stiffer and recurved into a strong hook shape.
Where does it grow?
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.
How Does it Reproduce?
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.
How Do I Control It?
General Control Strategy
Current control practices in many areas consist of mowing plants and leaving seedheads on the ground. Since seedheads of various ages have been shown to contain viable seed, management methods of common teasel need to take this into account to prevent the continual introduction of viable seeds.
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.
Maintenance of healthy of plant communities will help prevent re-infestation by common teasel. After the control of infestations, seed and plant areas with competitive grasses, forbs and other desirable plant species.
There are currently no biological control agents available for common teasel.
For More Information
See our Written Findings for more information about common teasel (Dipsacus fullonum).
Asotin County NWCB Fact Sheet on common teasel
Jefferson County NWCB Fact Sheet on common teasel
Whatcom County NWCB Brochure on common teasel
San Juan County NWCB Brochure on common teasel