Common teasel (Dipsacus fullonum L.) is a large biennial, easily recognized by its prominent spiny flower heads that persist throughout the year. Dried flower heads are often used in dried plant arrangements. Teasel is a common weed of roadsides and low maintenance turfgrass, meadows, and waste areas and is often found in damp, rich soils. It is rarely an issue in cultivated crops. This weed is distributed throughout most of the United States except for the northern Great Plains. It’s most commonly seen in the Northeast, including New York, Pennsylvania, and New Jersey, but less common in the New England. It can sometimes also be found in the Pacific Coast states.
Plants develop as basal rosettes. Young leaves are oval to egg-shaped, with toothed margins; surfaces have a wrinkled appearance. As the plant matures, basal leaves are widest above the middle, tapering to the base, with rounded teeth along the margin. Basal leaves generally die early in the second season when the erect stem and flowers are produced. Stems are angled, marked with fine parallel lines, and covered with many short downward-turning prickles, especially toward the top of the plant. Leaves are opposite and prickly on the underside of the midrib. The root system consists of a shallow taproot with fibrous secondary roots.
Reproduction is by seed, with seeds commonly germinated in late summer and fall. Plants usually overwinter as basal rosettes. Flowers are present from July to September in the second year of growth. Flower heads are cylindrical to egg-shaped, with large spine-like bristly bracts curving up around the head, the longer ones surpassing the head in length. Heads are covered with straight spines. Flowers are pale purple lobes, giving the head a purple thistle-like appearance. After seed production, woody erect stems and characteristic dead flower heads persist throughout the winter.
To learn more about Common Teasel you can visit the following sites:
Here is also a helpful video from University of Wisconsin Cooperative Extension:
Resource: Uva, Richard H., Joseph C. Neal, and Joseph M. DiTomaso. Weeds of the Northeast. Ithaca: Comstock Pub. Associates, 1997. Print.