Equisetum telmateia

Description

It is a herbaceous perennial plant, with separate green photosynthetic sterile stems, and pale yellowish non-photosynthetic spore-bearing fertile stems. The sterile stems, produced in late spring and dying down in late autumn, are 30–150 cm (12–59 in) (rarely to 240 cm (94 in)) tall (the tallest species of horsetail outside of tropical regions) and 1 cm (0.39 in) diameter, heavily branched, with whorls of 14–40 branches, these up to 20 cm (7.9 in) long, 1–2 mm (3⁄64–5⁄64 in) diameter and unbranched, emerging from the axils of a ring of bracts; the main stem itself is whitish, without chlorophyll or stomata. The fertile stems are produced in early spring before the sterile shoots, growing to 15–45 cm (5.9–17.7 in) tall with an apical spore-bearing strobilus 4–10 cm (1.6–3.9 in) long and 1–2 cm (0.39–0.79 in) broad, and no side branches. The spores disperse in mid spring, with the fertile stems dying immediately after spore release. It also spreads by means of rhizomes that have been observed to penetrate 4 metres (13 ft) into wet clay soil, spreading laterally in multiple layers. Occasionally plants produce stems that are both fertile and photosynthetic.