Teasel (Dipsacus sp.) is classified as an invasive plant. It was originally brought to North America from Europe and has thrived here. Even though it is considered a noxious weed, this biennial’s form and flower are striking. The first year, Teasel produces a rosette of leaves. The second year the flowering stem can grow to a height of almost eight feet.
Teasel is unique in the way in which it blooms. Flowers first form in a ring around the middle of the head. The ring of flowers grows in width over a few days, but since the flowers are relatively short lived, the center of the booming section may die off leaving two rings, one growing towards the top and one towards the bottom. Several long, leaf-like bracts branch out from the base of the flower and curve upward around the head.
Historically, Teasel’s seed head was used in the textile industry to raise the nap on woolen cloth. Although it is invasive and does crowd out native plants, Teasel redeems itself somewhat by providing insects with nectar and birds with a multitude of seeds (2,000 – 3,000/head). (Photo: Painted Lady (Vanessa cardui) on Teasel)
Teasel is an introduced biennial, considered an invasive plant in the U. S. due to its ability to crowd out native species. Nonetheless, the seed head that remains after the three- to eight-foot plant has flowered is strikingly beautiful. It consists of a cone of spine-tipped, hard bracts, or modified leaves. Since the Middle Ages, Europeans have used dried seed heads of the teasel plant to raise the nap on woolen cloth. Teasing wool creates a soft, almost furry texture on one side of the cloth. (Baize, the cloth traditionally used to cover pool and card tables, is a classic example of wool that has been teased.)
Because of the demand for these seed heads, farmers in 19th century New England grew fields of teasel, with each acre yielding up to 150,000 heads. In the autumn, they would be harvested and dried. Teasel heads wore out quite quickly with use, so wool manufacturers needed a constant supply of them. Eventually a machine, the “teasel gig,” replaced the seed heads. Today fine combs with steel wires raise the fibers on teased fabrics, although the consensus is that there is still no substitute for teasel heads in producing the finest cloth.