Rushlike survivor of Carboniferous Age in Europe, North America. There are several species, but E. hyemale is most common. Slender, hollow, 4 feet stems are bright green, showing a ring of black and ash-gray at each joint. Spores are borne in conelike spikes at stem ends. Miniature E. scirpoides is similar but only 68 inches high. The common name horsetail refers to the bushy look produced by the many whorls of slender, jointed, green stems that radiate out from joints of main stems on some of the other species.
Although horsetail is effective in some garden situations, especially near water, use it with caution: It is extremely invasive and difficult to get rid of. Best confined to containers without drainage holes. In open ground, use paving or steel edging sunk in ground to confine roots.