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Equisetum arvense, the Field Horsetail or Common Horsetail, is a herbaceous perennial plant, native throughout the arctic and temperate regions of the northern hemisphere. It has separate sterile non-reproductive and fertile spore-bearing stems, growing from a perennial underground rhizomatous stem system. The fertile stems are produced in early spring and are non-photosynthetic, while the green sterile stems start to grow after the fertile stems have wilted, and persist through the summer until the first autumn frosts. The sterile stems are 10–90 cm tall and 3–5 mm diameter, with jointed segments around 2–5 cm long with whorls of side shoots at the segment joints; the side shoots have a diameter of about 1 mm. Some stems can have as many as 20 segments. The fertile stems are succulent-textured, off-white, 10–25 cm tall and 3–5 mm diameter, with 4–8 whorls of brown scale leaves, and an apical brown spore cone 10–40 mm long and 4–9 mm broad. It has a very high diploid number of 216 (108 pairs of chromosomes).
Pastures, fields, meadows, grassy areas, roadside/trailside, rocky slopes, forested wetlands, lake shore, marshes/swamp, steam/river banks, etc.
Spotted at Cougar Mountain Regional Wildland Park (Anti-Aircraft Peak Traihead) in Issaquah, WA.