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USDA Symbol: EUOB4
ODA rating: A
Oblong spurge risk assessment
Noxious weed listing process
Oregon oblong spurge distribution
Other common names
egg leaf spurge
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Images courtesy of Tom Forney, Oregon Dept. of Agriculture
If images are downloaded and used from the ODA web site please be sure to credit the photographer.
Oblong spurge is a weedy escaped ornamental species of Euphorbia. This plant is an exotic perennial herb that produces up to 20 stems on a woody rootstalk with the plants reaching nearly three feet in height. The alternate, oblong leaves are glabrous (smooth and hairless) with finely toothed margins. Leaves and stems exude a milky sap when cut; skin contact should be avoided. Numerous yellowish-green bracts and flowers typical to most spurges develop at terminal tips. Seedpods have a waxy appearance, and when mature, ripened pods forcefully eject their seeds for localized dispersal.
In western Oregon this plant thrives in moist grassy bottomland even with significant competition. In other states, infestations appear to be spreading more aggressively, perhaps the result of it establishing on drier sites with little competition. Oblong spurge has a great capacity to infest riparian areas in Washington and Oregon. It is well adapted to a wide range of shrub and pine forest environments. In California it has been found associated with French broom, blackberry and in dry drainages along roadsides.
Distribution in Oregon
Oblong spurge was discovered in Marion County on August 30, 1991 (Halse and Coombs). It was found in Salem, at a pond and it's drainage ditch on the state penitentiary grounds. The ditch leads into the Mill Creek drainage, and several small sites have been found downstream. It is suspected to have been introduced from California in contaminated flax or machinery that was used at the Oregon State Penitentiary flax mill in the early part of the 1900's, it has slowly expanded its territory on the penitentiary property.
For a collection of spatial information on the distribution of this plant in Oregon go to Oregon WeedMapper.
Biological control agents are not used on "A" listed weeds in Oregon. This weed is being managed for eradication.
Printable trifold oblong spurge brochure (pdf)