Teasel family (Dipsacaceae)
Description: This herbaceous biennial plant consists of a low rosette of basal leaves during the first year. These basal leaves are up to 12" long and 3" across, oblanceolate, and crenate. During the second year, Teasel develops stems with opposite leaves, becoming 2½–6' tall; it branches occasionally and is rather lanky. The hairless stems are pale green to reddish green; they have scattered white prickles and flat longitudinal ridges. The opposite leaves are up to 12" long and 3" across; they are green, yellowish green, or reddish green, lanceolate to linear-lanceolate, ascending to spreading, and rather stiff in texture. Their margins are smooth, slightly prickly, or irregularly toothed. On the upper surface of each leaf, there is a white central vein, while on the lower surface this vein has stout prickles. The lower opposite leaves are sessile, while the upper opposite leaves are perfoliate or clasping. All leaves are hairless.
Each upper stem terminates in a stout spike of flowers up to 4" long and 1½" across; the long flowering stalk is naked and prickly. Initially, each floral spike is ovoid in shape, but it later elongates and becomes oblongoid. At the base of each floral spike, there are several linear bracts up to 6" long that curve upward, surrounding the spike. These bracts have scattered prickles on their sides and undersides. Narrow tubular flowers and their buds are densely crowded together all around the spike. These flowers begin to bloom in the middle of the spike, but later they bloom in separate rings toward the top and bottom of the spike. The corolla of each flower is narrowly tubular and about ½" long; it has 4 outer lobes that are small and rounded. The corolla is usually pale purple or lavender toward the outer lobes, but it is white toward the base. Each flower has 4 exerted stamens with white filaments and pale purple or lavender anthers. The calyx is tiny and insignificant. At the base of each flower, there is a bract originating from the receptacle that is straight and about the same length as the flower. This bract is usually pale green, stiff, and linear in shape. However, the bracts of the receptacle toward the apex of the floral spike are significantly longer than the flowers. Like the flowers, these bracts are densely crowded all around the floral spike, providing it with a pincushion-like appearance after the flowers have withered away. The blooming period occurs from mid-summer into fall and typically lasts about 2 months for a colony of plants. After the blooming period, the entire plant gradually turns brown; the stalks and floral spikes persist through the winter. Each flower is replaced by a ridged 4-angled achene that is irregularly bullet-shaped and up to ¼" long. The root system consists of a stout taproot.
Cultivation: The preference is full or partial sun, mesic conditions, and mildly acid to alkaline soil containing loam or clay-loam. The leaves are occasionally bothered by powdery mildew.
Range & Habitat: The non-native Teasel occurs occasionally in most areas of Illinois, although it is less common or absent in the NW section of the state (see Distribution Map). It was introduced into North America from Eurasia. Habitats include mesic prairies (especially cemetery prairies), degraded grassy meadows, savannas, woodland borders, pastures and abandoned fields, landfills, roadsides, and waste areas. Teasel is an introduced species that can invade high quality prairies and savannas. It is difficult to eliminate from such habitats. Teasel also adapts readily to disturbed habitats.
Faunal Associations: The nectar of the flowers attracts bumblebees and other long-tongued bees, green metallic bees (Agapostemon spp.), bee flies (Bombyliidae), butterflies, and skippers. Green metallic Bees also collect pollen. The caterpillars of Papaipema arctivorens (Northern Burdock Borer Moth) bore through the stems of Dipsacus spp. (Teasels). Mammalian herbivores shun the tough prickly foliage of Teasel; even in overgrazed pastures, cattle nibble on the outer tips of the leaves and little else. Except for flower-visiting insects, the ecological value of this introduced species to wildlife is low.
Photographic Location: A degraded floodplain meadow in Champaign, Illinois.
Comments: The floral spikes from a cultivated form of Teasel were used to raise the nap of woolen fabrics. This was possible because the bracts of the receptacle in the cultivated form had hooked tips. In contrast, the wild form of Teasel (as described here) has bracts with straight tips. In horticulture, the dried floral spikes and their stalks are used in dried flower arrangements. In the past, the floral spikes and stalks were used as material in funereal wreaths, which were placed alongside the gravestones of the deceased. This is one of the reasons why Teasel occurs in cemetery prairies. With its spiny-looking floral spikes and prickly stems, Teasel has a distinctive appearance that resembles no native plant in Illinois. Another introduced species, Dipsacus laciniatum (Cut-Leaved Teasel), can be distinguished from ordinary Teasel by its pinnatifid leaves and straight bracts at the base of the floral spikes; these bracts spread outward, but they do not curl upward. The flowers of Cut-Leaved Teasel are white, while those of ordinary Teasel are usually pale purple or lavender; however, strains of Teasel with white flowers may occur in the wild. A scientific synonym of Teasel is Dipsacus sylvestris.