This image shows fescue grass roots, which exude a yellow material that contains an amino acid called m-tyrosine as a major component. The chemical structure for m-tyrosine is superimposed on the photo.

Cornell researchers identify natural herbicide that controls weeds around some common lawn grasses

Certain varieties of common fescue lawn grass come equipped with their own natural broad-spectrum herbicide that inhibits the growth of weeds and other plants around them.