Glyphosate (N-(phosphonomethyl) glycine) is a non-selective systemic herbicie, absorbed through the leaves, injected into the bole, or applied to the stump of a tree, used to kill weeds, especially perennials and broadcast or used in the cut-stump treatment as a forestry herbicide. Some crops have been genetically engineered to be resistant to it. Glyphosate was first sold by Monsanto under the tradename Roundup, but is no longer under patent.