Leafy spurge (Euphorbia esula L.), a member of the Spurge family, was introduced from Europe. It is a creeping perennial which reproduces by seed and extensive creeping roots. The roots can extend as deep as 30 feet and are extremely wide-spreading. The shoots grow erect, 1 to 3 feet high, are pale green and un-branched except for flower clusters.
Leaves are alternate, narrowly linear with smooth margins, about 1/4 inch wide, and 1 to 4 inches long. The small yellow-green flowers are enclosed by a pair of yellowish-green, heart-shaped bracts. The bracts have the appearance of flowers. The pods are three-seeded. The plant, including the root, has a milky latex that is damaging to eyes and sensitive skin.
Leafy spurge is an extremely difficult plant to control because of its extensive sprouting root system and is one of the most serious noxious weed threats in Colorado.
It is adapted to a wide variety of habitats in the state and is very competitive with other plant species. If it becomes established in rangeland, pasture and riparian sites, it may exclude all other vegetation due to its competitive nature. Although it is unpalatable to cattle, sheep and goats eat spurge, do well on it, and are useful biocontrol tools.