Marsh horsetail

Marsh horsetail is a poisonous perennial pteridophyte with a thin smooth green stalk. The 20 to 40 cm tall marsh horsetail often grows irregular and sparse branches topped by yellow-brown spore cones.

The marsh horsetail grows in semi-fertile and nutrient-rich marshes. It thrives best in different groves, morass-fens and near springs. It can be found throughout the northern parts of Eurasia and North America.

The marsh horsetail is very toxic, and it is important not to confuse it with the field horsetail (Equisetum arvense) which is used as a herbal remedy. The lower limb of the marsh horsetail is clearly shorter than the shank of the stem; while in the field horsetail, it is much longer. The field horsetail also has different spore-bearing stems that grow in spring. Marsh horsetail in pastures can poison grazing animals.

Marsh horsetail has benefitted from human activities and grows quite often on road and track sides, ditches, and especially in peat-based fields and pastures. The peak era for horsetails was during the carboniferous period about 300 million years ago, so the adaptation ability of this species group is clearly high.