The Collaborative International Dictionary of English v.0.48:
Snakeweed \Snake"weed`\, n. (Bot.) (a) A kind of knotweed (Polygonum Bistorta). (b) The Virginia snakeroot. See Snakeroot. [1913 Webster]The Collaborative International Dictionary of English v.0.48:
Adderwort \Ad"der*wort`\, n. (Bot.) The common bistort or snakeweed (Polygonum bistorta). [1913 Webster]