Common teasel (Dipsacus fullonum L.)
Common teasel is native to Europe and is now widespread in North America. It is spreading rapidly in parts of the Pacific Northwest, particularly in moist sites such as irrigation ditches, canals, riparian corridors, and other disturbed areas. In fall, dried stems and seed heads are sometimes harvested and silvered or gilded for decorative winter arrangements.
Common teasel is a stout, taprooted biennial forb. During its first year, it forms a basal rosette of leaves. In the second year, it produces a tall flowering stalk that may reach up to 6 feet in height and branches in the upper portion.
Stems are striate-angled and covered with rows of downward-pointing prickles. Leaves are long, lanceolate to oblong, with entire margins and prominent veins. Basal leaves may appear wavy or wrinkled and typically die back early in the second growing season. Stem leaves are opposite and fused at the base, forming cup-like structures that collect and hold rainwater. Sharp spines occur along the midrib on the underside of leaves and along the stems.
Flowering occurs from early summer through fall (typically July to August at peak bloom). Flowers are light purple and borne in dense, spiny, egg-shaped heads that are 2 inches or more in length. Each small flower is subtended by spine-like bractlets, and the corolla is four-lobed. Involucral bracts at the base of the flower head are generally longer than the head itself. Fruits are four-angled and contain a single seed. Seeds are rectangular, brown, and deeply grooved.
Common teasel has a deep taproot that allows it to access moisture and makes established plants more resilient.
Quick ID Guide
Life Cycle:
• Biennial
• First-year rosette
• Second-year flowering stalk
Height:
• Up to 6 feet tall
Stems:
• Striate-angled
• Downward-pointing prickles
• Branched above
Leaves:
• Lanceolate to oblong
• Opposite and fused at base (cup-forming)
• Prominent veins
• Spines on midrib and stem
Flowers (Early Summer–Fall):
• Light purple
• Dense, spiny, egg-shaped heads
• 2+ inches long
Roots:
• Deep taproot
Seeds:
• Brown
• Rectangular
• Deeply grooved
Management Options
Prevention and cultural control strategies should be emphasized whenever possible. There are currently no approved biological control agents for common teasel.
Because common teasel has a taproot, it can be effectively managed by hand pulling or digging, ensuring the entire root is removed below the crown. Plants are easiest to control in the rosette stage.
Mowing or chopping is not recommended, as it may stimulate additional flowering. If flowering plants are present, seed heads should be bagged and disposed of in the trash to prevent spread.
Large infestations may require herbicide applications. Spring or fall treatments targeting rosettes are recommended, though treatments on bolting plants can also be effective. Always read and follow herbicide label directions before application. Contact Sublette County Weed & Pest for assistance with product selection, rates, and timing.
