There are 15 species of equisetum found worldwide; field horsetail (Equisetum arvense) is common in Central Europe.
Field horsetail grows from tuber-bearing rhizomes. The erect sterile stems are 10–90 cm tall and have a diameter of 3–5 mm. They consist of jointed segments around 2–5 cm long with whorls of green side shoots – the leaves of field horsetail – at the segment joints. Some stems can have as many as 20 segments. The side shoots have a diameter of about 1 mm; my photo shows several of them.