Prostrate Spurge

Prostrate Spurge (Euphorbia supina) (Euphorbia prostrata)

This weed is native to the United States, especially the eastern and southeastern parts of the country. A common name for it is Spotted Spurge (Euphorbia maculata), which technically is slightly different from Prostrate. Overall consider both Prostrate and Spotted Spurge to be the same.

From the family Euphorbiaceae, this genus Euphorbia has about 1000 species. Many are diverse in appearance, while others are very similar in appearance. There can be a great deal of confusion differentiating them, overall there are a handful we in North America will find very bothersome.

Other widespread genus that we are likely to confuse with include Petty Spurge (Euphorbia peplus), Sun Spurge (Euphorbia helioscopia), Leafy Spurge (Euphorbia esula) and Flowering Spurge (Euphorbia helioscopia). Petty and Sun Spurge are annuals. Leafy and Flowering Spurge are perennials.

Prostrate spurge is a summer annual that likes hot, hot temperatures. It is poisonous and is sometimes mistaken for Prostrate Knotweed, which is similar in appearance. Like Knotweed, this grows prostrate, laying flat or level to the ground and spreads wide. It can be found growing erect, but not often. Visually the big difference with telling Spurge apart from Knotweed is that the leaves have a purple spot in the center. Leaves are also hairy, grow opposite of each other and are toothed. Sometimes there can be a red outline around them. There is a main vein from the base of leaf where it is attached to a short petiole, or stalk attached to the main stem. Stems are usually red, sometimes green.

All these spurges have tiny, greenish-white flowers surrounded by visible bracts, or a leaf /leaf-like part usually found at the base of flower. Depending on location in country, weeds flower May - October. Earlier than this in the southwest.

Spurges grow from a single taproot, which then multiply out from the base. They grow fast branching out form dense mats in their short life-cycle. They thrive in cultivated soils such as sidewalk cracks and along roadsides. Unlike prostrate knotweed, spurges are not good with preventing soil erosion.

For manual removal it is important to wear gloves. When pulled or broken all spurges bleed a milky, bitter juice that can cause skin irritations on contact. It is rare for spurges to have a toxic effect but should be noted, as it has been found for some.

For chemical control, it's best to use Preemergents in spring before germination starts. Starting at about 60 degrees. Post-emegents when young and tender best during growing season.

Seeds are long lasting in the soil. The good news:
With spurges they can be easily suppressed by
mulches or densely planting perennials in the
area that the weed grows.

FYI:

One perennial from this genus is Mrs Robb's bonnet (Euphorbia amygdaloides var. robbiae), which is a wood spurge. It is very popular as a deer-resistant, part-shade plant that many gardeners may want to keep in their weed garden.

With similarities to Prostrate Spurge, the flowers are yellow and
it is important to note this plant can become an invasive.

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