Teasel family (Dipsacaceae)
Description: This introduced biennial plant is 2-6' tall. During the 1st year of development, it consists of a rosette of basal leaves about 1-3' across. These basal leaves are up to 16" long and 4" across. They are lanceolate or narrowly ovate in outline, but their margins are pinnately lobed (pinnatifid), coarsely toothed, and ciliate. During the 2nd year of development, one or more tall flowering stalks emerge from the basal rosette. These stalks are stout, round or angular, and covered with white prickles. There are opposite leaves at intervals along the lower half of the stalks. These opposite leaves are smaller in size and have shallower lobes than the basal leaves, otherwise they are much the same. Their bases are perfoliate or strongly clasp the stalks.
Each stalk terminates in a cylindrical flowerhead about 2-4" long and 1½" across. At the base of this flowerhead are several long bracts about 2-4" long that taper to a sharp point. They are folded along the middle and have small prickles underneath. These bracts are more or less straight and spread outward from the base of the flowerhead, rather than curling upward. The flowers are densely packed together all around the flowerheads. Each flower has a single bractlet about ¾" long at its base that tapers to sharp straight point. These bractlets are longer and more conspicuous than the flowers. The corolla of each flower is narrowly tubular and about ½" long, flaring outward slightly at its apex into 4 small petals. This corolla is usually white rather than lavender. There are 4 stamens with white anthers that are exerted from the corolla tube. The calyx of each flower is small and inconspicuous. A wreath of flowers are in bloom together around the flowerhead, beginning at the bottom and gradually ascending to the top. The blooming period occurs from mid-summer to early fall, and lasts about 1-2 months for a colony of plants. The flowers are often fragrant. Each flower is replaced by an oblong seed that is 4-angled; it is truncate on one end and rounded on the other. The root system consists of a stout taproot. This plant spreads by reseeding itself, and occasionally forms colonies.
Cultivation: The preference is full or partial sun, mesic conditions, and fertile loamy soil. This plant will grow in poor soil, but its size will be reduced. During a hot summer drought, some of the lower leaves may turn yellow and fade away, otherwise this plant has few problems. It is often aggressive and hard to get rid off. Digging the plants out with a shovel helps, but the portion of taproot remaining in the ground may regenerate a new plant. Cutting off the flowerheads with a knife while leaving the rest of plant undisturbed is not adequate as a method of control, because Teasel is often strong enough to produce new flowering stalks.
Range & Habitat: Cut-Leaved Teasel has been observed primarily in NE and central Illinois, where it is occasional to locally common (see Distribution Map). This species is undoubtedly still spreading across the state. It was introduced into the United States from Europe as a horticultural plant. Habitats include mesic cemetery prairies, savannas, roadsides, weedy meadows along rivers, pastures, and waste areas. Teasel is sometimes found around cemeteries because wreaths for the deceased were made from the flowering stalks. While Cut-Leaved Teasel is normally found in disturbed areas, it also invades high quality natural areas and can become a serious pest.
Faunal Associations: The flowers attract bumblebees, bee flies, butterflies, and skippers. Insects with shorter mouthparts have trouble reaching the nectar. Some Halictid bees may visit the flowers to collect pollen. Mammalian herbivores shun Cut-Leaved Teasel as a food source because the foliage and flowerheads are quite coarse and prickly. In overgrazed pastures where there is little else for cattle to eat, this is one of the few plants that is left standing.
Photographic Location: An area of Judge Webber Park in Urbana, Illinois, that was subjected to disturbance from construction equipment.
Comments: Species of Teasel have very unique flowerheads that are quite prickly because of the bractlets of the flowers. During the rosette stage, they resemble some Lactuca spp. (Wild Lettuce), but become quite different in appearance after the flowering stalks develop. Cut-Leaved Teasel is similar in appearance to Dipsacus sylvestris (Common Teasel), which also occurs in Illinois. This latter species usually has lavender flowers and its leaves are entire rather than pinnately lobed. The bracts at the base of its flowerheads curl upward, while the same bracts of Cut-Leaved Teasel are straight and spread outward.