Illinois Exotic Species:
common teasel Dipsacus sylvestris

Common teasel is native to Europe. It was introduced to North America possibly as early as the 1700's. Common teasel may have been introduced with other teasel species or accidentally with other plant material from Europe.

Common teasel grows as a basal rosette of leaves for a minimum of one year, then sends up a flowering stalk and dies after flowering. During the rosette stage, leaves are oval or oblong. Leaves may be "hairy" in older rosettes. Common teasel blooms from June through October. Flowering plants have large, oblong, opposite, sessile leaves that form cups (the cups may hold water) and are prickly. Stems also are prickly. Teasel's unique flower head makes the plant easy to identify when blooming. Flowers are small and packed into dense, oval-shaped heads at the tip of the flowering stems. Common teasel usually has purple flowers. Flowering stems may reach six to seven feet in height. A single teasel plant can produce more than 2,000 seeds. Teasel grows in open sunny habitats. It sometimes occurs in high quality prairies, savannas, seeps and sedge meadows, though roadsides, dumps and heavily disturbed areas are its most common habitats.

Teasel has spread rapidly in the last 20 to 30 years. This rapid range expansion probably was aided by construction of the interstate highway system. Teasel has colonized many areas along interstates. Common teasel sometimes is used as an ornamental plant, and the dried flower heads are often used in flower arrangements. Both practices have assisted its dispersal. Teasel occurs widely in northern and central Illinois. It is an aggressive exotic species that has the capacity to take over prairies and savannas if it is allowed to become established. Without any natural enemies and without any control measures, teasel can exclude all native vegetation from an area.

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