What is "horsetails"

Equisetum \Eq`ui*se"tum\, n.; pl. Equiseta. [L., the horsetail, fr. equus horse + seta a thick,, stiff hair, bristle.] (Bot.) A genus of vascular, cryptogamic, herbaceous plants; -- also called horsetails.

Note: The Equiseta have hollow jointed stems and no true leaves. The cuticle often contains siliceous granules, so that one species ( E. hyemale) is used for scouring and polishing, under the name of Dutch rush or scouring rush.

n. (plural of horsetail English)