English: Marsh horsetail.
Clades: Equisetidae.
Region: Eurasia, North America, circumpolar, mountainous regoions.
Habitat: nutrient-rich wet meadows.
Content: alkaloids palustrine and palustridiene, which destroy vitamin B1; thiaminase enzymes; nicotine.
Ecology: poisonous to mammals, horses.
Use: to lower the production of dairy when cows would eat them in place of other preferable fodder.

BotanyType: fern; perennial.
Root: proliferating by runners.
Stems: 10 to 60 cm tall; upright; rough; furrowed; 1 to 3 mm diameter; 8 to 10 ribs, sometimes 4 to 12; branches whorled, scarce.
Leaves: loose; green; sheaths; with 5 to 10 narrow, dark teeth; teeth are light at the edges; internodes much shorter than the leaf sheath of the stem.
Spores: spread by the wind; four long ribbon-like structures; on strobili, rounded on the top; from June to September.