1Any of various plants having straight, slender, especially hollow or unbranched stems, especially field horsetail (Equisetum arvense), and (US) (more fully "Indian pipeweed") a North American desert plant having erect leafless stems which are swollen near the top, Eriogonum inflatum (family Polygonaceae).

2Pipe tobacco; (also) the prepared leaves of any plant used as a substance to be smoked in a pipe.