Equisetum hyemale - Common scouring rush is a spreading, reed-like perennial to 3 ft (0.9 m) tall. The evergreen stems are cylindrical, about 1/3 in (0.8 cm) in diameter, jointed, hollow, usually unbranched, and have rough longitudinal ridges. The tiny leaves are joined together around the stem, forming a narrow black-green band or sheath at each joint. Like other Pteridophytes (ferns and their relatives), scouring rush does not produce flowers or seeds. Instead it develops a brown, cone-shaped, spore-producing strobilus at the tip of fertile stems, which are shorter than the infertile stems. The spores themselves are microscopic. Scouring rush spreads by shallow rhizomes (underground stems) and is easily propagated by dividing the clumps and immediately replanting the rooted individual plants.