Skip to main content

The Dirt | Weed of the Month May 2025 | Oblong/Eggleaf Spurge (Euphorbia oblongata)

Poster about oblong spurge (Euphorbia oblongata), a noxious weed needing management, with contact info and images.
May Weed of the Month flyer featuring Oblong spurge.

Our weed of the month appears right as its vibrant yellow coloring does. Oblong or eggleaf spurge (Euphorbia oblongata) is a perennial plant that is most known for its striking yellow-green bracts that look like flowers. It grows from a woody taproot on upright, villous stems that are either green or red in color. Its oblong leaves either alternate up or whorl around the stem and leak milky white sap when broken, which can be irritating to the skin. Because of its unique appearance, it was commonly sold and planted as a garden ornamental species that thrives in both sunny and rocky and partially shaded, clayey areas.

Bright yellow-green flowers with star-shaped petals and lush green leaves in a dense cluster.
Oblong spurge with yellow bracts and seed heads. Photo credit: Michael Ahr.
Yellow wildflowers growing between a concrete surface and a plant with green leaves.
Oblong spurge with yellow bracts and beginning flowers. Photo credit: Cierra Dawson.
Green plants and shrubs with different textures and leaf shapes growing in a garden.
Oblong spurge before yellow bracts emerge. Photo credit: Cierra Dawson.
Bright yellow-green flowers with star-shaped petals and lush green leaves in a dense cluster.
Yellow wildflowers growing between a concrete surface and a plant with green leaves.
Green plants and shrubs with different textures and leaf shapes growing in a garden.

 However striking, oblong spurge is a priority weed for Early Detection and Rapid Response (EDRR) protocols in Benton County. It spreads aggressively once established and can migrate out of garden beds and plant pots. As of May 2025, there are just over 100 confirmed locations of oblong spurge across Benton County. While that sounds extensive, the good news is that many of those locations have small populations that are managed by simple weeding practices—a success of EDRR protocols!

The best way to remove small populations is to manually pull or dig the entire plant out of the ground, including the woody taproot. It is best to pull this species in early spring while the ground is still somewhat soft. Herbicide control is recommended for larger infestations.

Overall, there is still a possibility to control this species in Benton County, so if you see something, say something. Benton SWCD can help you remove this species free of charge. Report sightings of this plant by emailing Cierra Dawson at cierra@bentonswcd.org. Alternatively, you can report sightings online to the Oregon Invasive Species Hotline or call 1-866-INVADER.

Thank you to the Oregon State Weed Board and Oregon Department of Agriculture for providing funding for Benton SWCD's continuous effort to "Purge the Spurge!"