Rocky Mountain Spurge
Euphorbia robusta (Engelm.) Small
Family: Euphorbiaceae, Spurge
Genus: Euphorbia
Synonyms: Euphorbia brachycera
Other names: horned spurge
Nomenclature: robusta = robust
Nativity / Invasiveness: Montana native plant
Medicinal plant
Toxic plant

General: hairless or short-hairy perennial with milky juice, with a deep taproot and branched crown and with erect stems 10-30 cm tall, usually branched above.

Leaves: thick and rather fleshy, entire, the lower ones alternate, nearly stalkless, ovate to broadly oblong, slightly pointed, 1-2 cm long, the upper ones opposite or sometimes whorled at the base of the branches.

Flowers: greenish-yellow, naked, lacking petals and sepals, borne in small clusters inside involucres 3 mm long, hairy within and often toothed between the 4 reddish, short-horned glands, these inside a pair or 3 floral leaves that are broadly cordate to ovate, 1-2 cm long. These small clusters on long stalks in umbel-clusters. Male flowers many, included in the involucre, each represented by a single stamen, female flower single and terminal, often protruding from the involucre, 3-celled. June-August.

Fruits: capsules, depressed-spherical, smooth, about 4 mm long. Seeds slightly over 2 mm long, gray, finely pitted in a net-like pattern.


Dry areas in the foothills and lower mountains, in many parts of MT. Also mostly e. of the continental divide, from SD and s. to NM and AZ.
Medicinal Uses

Rocky Mountain Spurge was used medicinally by the Navajo Indians. For cathartic purposes a compound infusion of plants was taken for purging. The plant was also rubbed as a liniment or poultice of plant applied to boils and pimples. As a gynecological aid a compound infusion of plants was taken for confinement.

Toxic Properties

The acrid, milky juice (latex) can inflame and blister sensitive skin. If the plants are eaten, they cause vomiting, and in quantity they can prove fatal. Even honey made from the nectar from some spurges is mildly poisonous. Sheep are able to eat leafy spurge, so they are being used in biological control programs.

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