Nourish your body from within with the prehistoric strength of Horsetail (Equisetum arvense ), also widely known in classical folk herbalism as Shavegrass or Bottle-Brush. Descended from ancient, tree-sized plants that covered the earth over 300 million years ago, Horsetail is world-renowned as one of the richest botanical sources of natural organic silica, silicic acid, and bioavailable minerals on the planet.