Leafy Spurge or an Imposter?

Updated May 30, 2024

Eric Jones

Assistant Professor and SDSU Extension Weed Management Specialist

Additional Authors: Philip Rozeboom
Two pictures of bright, green plants with yellow flowers.
Figure 1. Different stands of leafy spurge (left) and hedge mustard (right). At a distance, these plants can be confused with each other.

Written collaboratively by Eric Jones, Philip Rozeboom, Jill Alms, and David Vos.

Across South Dakota, yellow flowers are appearing all over the landscape. First thoughts when seeing these yellow flowers in pastures/rangeland and in roadsides might be: “That is leafy spurge!”. Leafy spurge is a statewide noxious weed that can be difficult to manage. However, are the yellow flowers leafy spurge or another species?

Weed Identification

In some cases, hedge mustard can be easily confused for leafy spurge from a distance due to the yellow, showy flowers (Figure 1). However, upon further investigation, it is evident that the flowers (Figure 2) and leaves (Figure 3) are quite different between the two species.

Flowers

Two pictures: The left picture consists of a green leafy spurge plant with yellow flowers. The right picture is of a pasture with a green hedge mustard plant with yellow flowers in the foreground.
Figure 2. The yellow, showy bracts (modified leaf surrounding a flower) of leafy spurge (left) and the small clusters of yellow flowers with siliques (slender seed pods) of hedge mustard (right). While easily confused with each other at a distance, closer inspection shows that the species are different.

Leaves

Two pictures: the top one has a white background with green leafy spurge leaves that are slender. The bottom picture also has a white background, but the green hedge mustard leaves are large and deeply lobed.
Figure 3. Long, thin leaves of leafy spurge (left) that exudate a white, milky sap when removed from the stem and the large deeply, lobed leaves covered in short, dense hairs of hedge mustard (right).

Leafy Spurge: Leafy spurge has large, yellow bracts (modified leaf surrounding the flower) and long, thin leaves. When leaves are removed from the plant, a white, milky sap is exudated from the stem. Leafy spurge spreads by rhizomes (underground stems) and seed. Therefore, patches of leafy spurge could be a singular plant.

Hedge Mustard: Hedge mustard has small clusters of yellow flowers and underneath the flowers are siliques (slender seed pods). The leaves are deeply lobed and covered in small, dense hairs. Hedge mustard reproduces by seed; therefore, the patches of these plants are all individual plants.

Similar Plants: While hedge mustard is a common plant that can be confused with leafy spurge at a distance, other plants can be confused with hedge mustard and leafy spurge. Other species could include sweet clover or goldenrod (Figure 4).

Two pictures: the left picture has a white background and a green stemmed sweet clover plant with yellow flowers. The right picture has a blurred, outside background with a goldenrod plant with yellow flowers in the foreground.
Figure 4. Sweet clover (left) and goldenrod (right) can also be confused with leafy spurge when seen at a distance. However, the vegetative morphology of all these species is quite different under careful inspection. (Courtesy: Tom Heutte, Rob Routledge;

Management Tactics

While all these plants may need to be managed in a pasture/rangeland setting, proper identification is important as different tactics will be effective on the different species. Refer to the latest SDSU Extension Noxious Weed Control and Weed Control: Pasture and Range guides for selecting effective herbicides. While herbicides are effective, these are not the only tactics that can be utilized to manage leafy spurge and other weeds. Mowing, grazing, rotational grazing, and hand weeding are all viable options to manage these weeds. Additionally, the leafy spurge beetle manages leafy spurge by feeding on the plant. While, not as effective when used alone, the leafy spurge beetles are a great complementary tactic; especially in areas that are not easily accessible.

Related Topics

Corn Weeds, Soybean Weeds, Wheat Weeds, Range, Grassland, Pasture

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