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Species of the month

Great Horsetail

Equisetum telmateia

Some facts about this horsetail:

Height: 40–150 cm (rarely 2 m).

Stem diameter: 1 cm.

Habitat: moist woodlands with a seasonal temperate climate.

Distribution: Europe (E. t. subsp. telmateia), and western North America (E. t. subsp. braunii).

Conservation status: Least Concern

First described: by Ehrhart in 1783.

The horsetails (class Equisetopsida) are an ancient group of spore-bearing vascular land plants. First evolving during the Devonian period, they developed in the Carboniferous period into some of the largest plants of the time, some becoming trees of 30 metres or more tall with stout trunks. With the evolution of seed plants, their dominance waned substantially, and now only a little over 20 species, all in the one genus Equisetum, still survive. Despite this, the genus has a nearly world-wide distribution, absent only from Australasia and Antarctica. Equisetum telmateia is one of the larger species, but like all the genus, is a herbaceous perennial plant. It produces its spores in a cone on separate stems in early spring (photo), with the foliage stems (above) growing in late spring and persisting through summer until autumn. In winter, only the underground rhizome survives.