Equisetum arvense or common horsetail is a tuberous, hairy rhizome with an erect stem. It does not have any leaves or flowers. When the stem is fertile, it resembles an asparagus. It withers and begin to turn brown in early summer, giving way to fresh, green stems of horsetail. The withered stems, which are hollow, are gathered to make horsetail extract. There are numerous benefits, both medicinal and cosmetic, of this extract.