Horsetail (Shavegrass) (Equisetum arvense), the field horsetail, common horsetail or Mare’s tail is a herbaceous perennial plant, native throughout the artic and temperate regions of the northern hemisphere. It has separate sterile non-reproductive and fertile spore-bearing stems, growing from a perennial underground rhizomatous stem system. The fertile stems are produced in early spring and are non-photosynthetic, while the green sterile stems start to grow after the fertile stems have wilted, and persist through the summer until the first autumn frosts.