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Biological Control of Leafy Spurge

The Weed—A Description


JPEG - Leafy spurge plant
Left:   Spurge plants can grow to be waist high. They bear pointed leaves and a cluster of yellow flowers with large, round, greenish-yellow bracts.


 

Right:   The root crown of spurge has adventitious buds that can sprout readily and produce new shoots, adding to the weed's rapid spread.

JPEG - Sprouting root crown of spurge
Leafy spurge grows in dense clumps with one or more shoots coming from a woody root crown. A milky latex seeps from the plant when it is cut or torn. Its nonwoody, hairless stems, which can reach 3 feet or more in height, hold alternate, usually pointed leaves. In summer, the weed develops a cluster of yellow flowers with large, round, greenish-yellow bracts.
Seeds grow inside a three-valved capsule. When the seed is ripe, the capsule bursts, shooting seeds up to 15 feet from the plant. Waterways and animals carry the seed further. Most of the seed germinates the first year, but a portion can germinate up to 7 years later.

The roots of spurge, which can descend 14 feet, help it crowd out neighboring species and store a large food reserve. Pink buds on the root crown sprout readily and produce new shoots, adding to the weed's rapid spread.

The first record of its introduction in North America places leafy spurge at Newbury, Mass., in 1827. By the early 1900's, the weed had been carried into the Western United States and Canada. Today, leafy spurge occupies more than 2½ million acres. It is concentrated most heavily in the northern Great Plains, particularly in North Dakota.

(A) habit (B) flower cluster
(C) capsule and (D) seeds
Leafy spurge. Above (A), habit. Top Right (B), flower cluster. Bottom Right (C), capsule and (D), seeds.


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