Snow-on-the-Mountain (Euphorbia marginata), also called snow-on-the-mountain, smoke-on-the-prairie, ghost weed, whitemargined spurge and variegated spurge, is a small shrub in the Euphorbiaceae or spurge family. The common name ‘Snow-on-the-Mountain” stems from the fact that patches of this plant look like snow in the distance.
They may be found all summer in abundance in the clay soil of pastures and roadsides at 4000 – 7000 ft, but should be handled with care since the milky juice is poisonous. When it touches the skin, it causes itching and inflammation, accompanied by pimples and blisters, much like these caused by Pacific Poisonous Oak.
At one point, a few cattlemen in Texas use the juice of this plant to brand cattle because they considered the scars to heal more satisfactorily than those made by a hot iron. In areas where it is abundant, this plant has caused honey to have a disagreeable taste and sufficient toxicity to cause vomiting and diarrhea.