Equisetum praealtum,[1] the scouringrush horsetail,[2] is a species of Equisetum (horsetail) native to North America and northeastern Asia.[1] It was formerly widely treated as a subspecies or variety of the European and west Asian species Equisetum hyemale (rough horsetail), and still is by some authorities.[3]
It is an evergreen herbaceous perennial plant, with green stems, each stem usually topped by a spore-bearing strobilus. The stems, produced in late spring and dying down a year and a half or two years later, are 18cm–150cmcm (07inches–60inchescm) (occasionally to 220cm (90inches)) tall and NaNmm diameter, usually unbranched; they are ridged, with 14–50 ridges, and bear whorls of blackish bracts. The young stems are produced in spring and develop an apical spore-bearing strobilus in summer; sometimes, in the second year, the stem will produce a few side branches tipped with further strobili. It also spreads by means of rhizomes, which form clonal colonies.[3] [4]
It is found in wet places, including roadside ditches, along rivers, lake shores, and in wet woods.[3]