Teasel is a biennial plant native to the Old World. Thanks to its uses in textile production, teasel has been widely exported around the world, and it now grows wild in a variety of locations. It is often treated as an invasive species, because it tends to choke out other plants, although some gardeners actively cultivate teasel because they find it aesthetically pleasing or interesting.
Like other biennial plants, teasel lives for only two years. It starts out in the form of a basal rosette of leaves which hugs the ground, storing up nutrients for the plant. In the second year of growth, a long stalk is sent up, and spiny egg-shaped flowers appear on the branched stems of the stalk. After the flowers go to seed, the stalk and plant die off. At first glance, teasel could be mistaken for a thistle, since both have spiny heads.
Dried teasel flowers have been used since Roman times to comb fabric made from wool, raising a soft, even nap in a process known as fulling. Modern textile companies use metal combs instead, since metal combs can be made more reliable and consistent, although some producers continue to use teasel pods. The advantage of teasel is that it will gently tease up the nap, breaking if it encounters strong resistance, whereas metal combs will rip the fabric before breaking, potentially damaging the textile.
There are a number of teasel species, all found in the genus Dipsacus, derived from a Greek word which means “to drink,” a reference to the cup-like formations created by the leaves of the plant. Water collects in these formations, leading some people to call teasel “Mary's cup.” One specific teasel plant, fuller's teasel, is renowned for having pods especially well suited to fabric fulling.
As an invasive species, teasel presents a number of problems. In addition to choking out native plants, teasel is also not very hospitable, with spiky flowers and sharp leaves which make it unpleasant to be around. As a result, many people work hard to eradicate teasel in their areas, cutting down the stalks before they have a chance to put out flowers which will go to seed, and gardeners who are considering planting teasel are sometimes encouraged to consider alternatives in areas where the plant is not native.