Common Teasel

Family: 
Dipsacaceae (teasels)
Description: 

A tall, thistle-like plant with stout, straight, prickly, branching stems. Grows from a basal rosette. During the rosette stage, leaves vary from somewhat egg-shaped to large and oblong leaves that are quite hairy with age. The taproot may be more than 2 feet long and 1 inch in diameter at the crown. Blooms June through October. Flowers are very small, massed on a cylindrical head, each with a tubular corolla, lilac to lavender, with stiff, narrow, pointed bracts longer than the flowers. The flower heads form at the tops of the stems. Leaves on flowering plants are large, oblong, opposite, stemless and form cups (which may hold water) and are prickly, especially on the lower midrib. The stems are prickly. Leaves on upper stems are lance-shaped, with scalloped (but not lobed) edges and without spines except on the midvein beneath.

Similar species: Cut-leaved teasel (D. laciniatus) has white flowers, blooms July through September and has irregularly pinnately lobed upper stem leaves.

Size: 
Height: to 8 feet.
Habitat and conservation: 
Found mostly in sunny fields, disturbed waste places and roadsides, often in large colonies, in both wet and dry habitats, along both highways and waterways, including on sandbars in streams. In Missouri, it is spreading to new areas, including natural sites. A single plant can produce more than 2,000 seeds, which can remain viable for at least 2 years. Teasel presents a difficult challenge for conservationists. Learn how to identify teasels and help to stop their spread.
Distribution in Missouri: 
Statewide.
Status: 
Invasive. Introduced from Europe to North America in the 1700s, it has been spreading along interstate highways. Teasel populations have flourished in the last 20 years due to late summer mowing along Missouri’s highways. The potential exists for teasel to invade lightly managed grasslands as well as high-quality natural areas. Cut-leaved teasel is more aggressive than common teasel and has severely threatened several northern and central Illinois natural areas.
Life cycle: 
For a year or more, teasel grows as a basal rosette. Then it sends up its flowering stalk and dies after flowering. A single plant produces thousands of seeds, and up 80 percent of those can germinate. Seeds typically don't disperse far, so teasels usually form colonies. Parent plants provide an optimal nursery site for their offspring--when the adult plants die, they bequeath to their offspring an area of bare ground where their own basal leaves had shaded out all other plants.
Human connections: 
In Europe and on our continent, teasel once was cultivated. The dried flower heads were used on spindles to raise the nap of woolen cloth by textile workers. The flower heads have also been used in dried flower arrangements and are sold as novelties. Please take care not to spread teasel seeds.
Ecosystem connections: 
Currently, invasive teasels in our state mainly occur along highways, but these aggressive weeds can outcompete native plants, especially in prairies and savannas. Their spines protect them from being eaten by most herbivores, so it’s up to humans to check their spread.