IUCN threat status:

Not evaluated

Comprehensive Description

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This perennial plant produces fertile and infertile shoots that are deciduous. Each fertile shoot is unbranched and about 4-8" tall. It has a jointed central stalk that is light brown, terete, glabrous, and about ¼" (6 mm.) across in diameter; it also has 8-12 shallow longitudinal ridges that are separated by shallow grooves. At the conjunctions of its joints (up to 6), there are sheaths with black triangular teeth (scale-like leaves) along their upper rims. This stalk terminates in a spore-bearing cone about ¾–1¼" long; the cone is lanceoloid-oblongoid in shape and rounded at its apex. The surface of the cone is mostly light brown, but it is covered with spore-bearing tubercles that have black, brown, and white markings. The fertile shoots develop during mid-spring, but they soon wither away after the cones have released their spores to the wind. The infertile (or vegetative) shoots have a very different appearance. They develop during mid- to late spring and persist until the fall. The infertile shoots are ½–2' tall; they have whorls of ascending branchlets along at least the upper two-thirds of their stems. The stems and branchlets of these shoots are slender, glabrous, and green. Each central stem is about 2-5 mm. across, consisting of several joints (up to 20) along its length. At the conjunctions of its joints, there are short sheaths with several triangular teeth (scale-like leaves) along their upper rims; these teeth become dark brown or black with age. The sheaths are appressed to slightly spreading and green to brown. The joints of the central stem are terete with 10-14 longitudinal ridges; sometimes there are fewer ridges. Young whorled branchlets are similar to the central stem, except they are shorter and more slender (about 1 mm. across) with fewer ridges (3-4). Later, they can become almost as long as the central stem. The branchlets have sheaths at the conjunctions of their joints like the central stem, but they have fewer teeth along their upper rims. These branchlets are unbranched. An infertile shoot may produce a small infertile cone at its apex that aborts prematurely, but this is very unusual. The central stem of Common Horsetail has a hollow center spanning about one-third of its diameter, while the branchlets are mostly solid. The root system consists of long rhizomes and secondary fibrous roots; sometimes small tubers are attached to the sides of the rhizomes. This plant often forms clonal colonies. Cultivation


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© John Hilty

Source: Illinois Wildflowers


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