smartweed definition by Webster's New World
Webster's New World College Dictionary Copyright © 2010 by Wiley Publishing, Inc., Cleveland, Ohio. Used by arrangement with John Wiley & Sons, Inc.
any of various knotgrasses (genus Polygonum) whose acrid juice may cause skin irritation
smartweed definition by American Heritage Dictionary
Any of various marsh plants of the genus Polygonum, having sheathlike stipules and small, densely clustered pink, white, or green flowers.