leafy spurge

from The American Heritage® Dictionary of the English Language, 5th Edition.

• noun A perennial spurge (Euphorbia esula) native to Eurasia, having small greenish flowers surrounded by yellow bracts, and often forming dense colonies in western North American rangelands.

from WordNet 3.0 Copyright 2006 by Princeton University. All rights reserved.

• noun tall European perennial naturalized and troublesome as a weed in eastern North America