Leafy Spurge (Euphorbia esula L.)
Leafy spurge is an aggressive herbaceous perennial that grows 1–3 feet tall and spreads through both seed and an extensive underground root system. It produces one or multiple erect stems from the crown, branching toward the top.
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Leaves are long, narrow (lanceolate), and arranged alternately along the stem. They may reach up to 4 inches in length. At the top of the plant, clusters of small yellow flowers are surrounded by distinctive heart-shaped yellow to yellow-green bracts (modified leaves), which give the plant its showy appearance.
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Flowers are arranged in umbels and consist of specialized structures called cyathia — cup-shaped whorls of bracts surrounding a cluster of male and female flower parts, similar in structure to a poinsettia.
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Leafy spurge flowers from late spring through late summer.
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All parts of the plant contain a white, milky latex sap that is released when stems or leaves are broken. This sap can irritate human skin and eyes and may cause temporary blindness. The plant is toxic to livestock and wildlife, causing severe irritation to the mouth and digestive tract. It is especially harmful to cattle and horses.
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Leafy spurge has both a deep taproot and an extensive network of rhizomes that may spread up to 35 feet horizontally and reach depths of 15 feet. Seeds are produced in three-seeded capsules. Seeds are small, gray to brown with a dark line on one side, and are dispersed explosively, potentially up to 20 feet from the parent plant
Quick ID Guide
Life Cycle:
• Herbaceous perennial
• Taproot with extensive rhizomes
Height:
• 1–3 feet tall
• Branched near top
Leaves:
• Alternate arrangement
• Long, narrow, lance-shaped
• Up to 4 inches long
Flowers (Late Spring–Late Summer):
• Small yellow flowers
• Heart-shaped yellow-green bracts
• Arranged in umbels
• Cyathia flower structure
Sap:
• White, milky latex
• Irritating and toxic
Seeds:
• 3 per capsule
• Gray to brown
• Explosively dispersed up to 20 feet
Management Options
Prevention and cultural control strategies should be prioritized. Ensure nursery stock is sourced from reputable dealers, free of leafy spurge contamination. When possible, visit nurseries during the growing season prior to purchase to prevent accidental introduction.
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Several biological control agents are available for leafy spurge Sublette County Weed and Pest has test locations with stainable populations.
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Small infestations may be managed through repeated hand pulling or digging, ensuring removal of the taproot and as much of the rhizome system as possible. Multiple treatments throughout the growing season are necessary. Wear gloves and long sleeves when handling leafy spurge due to the irritating latex sap.
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Mowing at regular two-week intervals can help prevent seed production. Intensive grazing with sheep or goats may reduce seed production, but care must be taken to prevent seed spread. Animals should be held in a pen for 3–5 days after grazing to allow seeds to pass through their digestive systems before moving them to new areas. Leafy spurge is toxic to cattle and horses.
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Larger infestations may require herbicide applications. Spring and early summer treatments prior to bloom are effective. Fall treatments after the first frost are also effective, as herbicides are readily translocated to the root system at that time. Always read and follow the herbicide label before application. Contact Sublette County Weed & Pest for assistance with product selection, rates, and application timing.
