leafy spurge

Euphorbia esula L.

Description from Invasive.org

Appearance: Euphorbia esula is an erect, perennial, herbaceous plant that grows from 2-3.5 ft. (0.6-1.1 m) tall. The stem is smooth and bluish-green. The plant produces a milky sap if stem is broken or a leaf is removed.
Foliage: Leaves are lance shaped, smooth and 1-4 in. (2.5-10.2 cm) long. They are arranged alternately along the stem, becoming shorter and more ovate towards the top of the stem.
Flowers: Flowering occurs in June, when yellow flowers develop in clusters at the apex of the plant.
Fruit: Fruits are 3 lobed capsules that explode when mature, propelling brown mottled ovoid seeds up to 15 ft. (4.6 m) away.
Ecological Threat: Large infestations of Euphorbia esula give the landscape a yellowish tinge due to the yellow bracts. Leafy spurge invades prairies, pastures, and other open areas. It is a major pest of national parks and nature preserves in the western United States. It can completely overtake large areas of land and displace native vegetation. This plant is native to Europe and was introduced accidentally into North America in the early 1800s as a seed contaminate.

Resources

Biological Control of Invasive Plants in the Eastern United States - USDA Forest Service
Weeds Gone Wild: Alien Plant Invaders of Natural Areas - Plant Conservation Alliance
Element Stewardship Abstract - The Nature Conservancy
Federal Noxious Weed Disseminules of the U.S. - USDA-APHIS
Weed of the Week - USDA Forest Service
Weed Field Guide - USDA Forest Service

Selected Images from Invasive.org

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Flower(s)
Steve Dewey, Utah State University, Bugwood.org
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Flower(s)
Chris Evans, University of Illinois, Bugwood.org
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Flower(s) Close up of flower, near Fort Collins.
William M. Ciesla, Forest Health Management International, Bugwood.org
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Foliage Foliage of leafy spurge at peak of fall coloring.
William M. Ciesla, Forest Health Management International, Bugwood.org
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Foliage
Bruce Ackley, The Ohio State University, Bugwood.org
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Feature(s) Close-up view of the stem of leafy spurge (Euphorbia esula), showing latex oozing from a wound.
L.L. Berry, , Bugwood.org
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Plant(s) in flower
Norman E. Rees, USDA Agricultural Research Service - Retired, Bugwood.org
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Infestation Meadow in Rist Canyon, west of Fort Collins, invaded by leafy spurge.
William M. Ciesla, Forest Health Management International, Bugwood.org
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Infestation
Steve Dewey, Utah State University, Bugwood.org
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Root(s) Roots
Steve Dewey, Utah State University, Bugwood.org
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Seed(s) Seeds, two with most of the caruncle still attached. Raphe exposed. FNW taxon.
Julia Scher, USDA APHIS PPQ, Bugwood.org
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Research research site
Norman E. Rees, USDA Agricultural Research Service - Retired, Bugwood.org
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Infestation
Utah State University , , Bugwood.org
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Plant(s) In grain
Steve Dewey, Utah State University, Bugwood.org
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