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Class B Noxious Weed

Swainsopea
Sphaerophysa salsula
 

Swainsonpea flower

Other common names: Austrian peaweed
 Plant family: Leguminoseae (Fabaceae)
Year listed:
Native to: Asia

Why is it a noxious weed?

Swainsonpea poses a serious threat to grain growing areas. Since swainsonpea seeds are the size of alfalfa seeds, it can be  a serious contaminant in the alfalfa grown for seed. It is known as a troublesome and persistent weed.

How would I identify it?
General Description: Swainsonpea is a perennial plant, much branched from the base with a woody taproot and rhizome.

Leaves:

  • pinnate
  • alternate on the stem
  • each leaf has 9 - 25 leaflets with silvery hairs

Flowers:

  • brick red, dry to purple
  • pea shaped 
  • occur on axillary stems

Stems:

  • axillary stems have 4 - 8 flowers

How does it reproduce?

Swainsonpea reproduces by seeds and rhizomes.

Where does it grow?

Swainsonpea is found growing along roadsides, waste areas, fence rows, and in cropland.

What is the distribution in Washington State?

 

 

 

Click on map to enlarge.
  • Swainsonpea has been documented in Yakima, Grant, Benton, Franklin, Walla Wall and Adams counties.
  • Distribution map based on 2003 data.

How do I control it?

General control methods:

Cultural: Information not available at this time.

Herbicide: Please refer to the PNW Weed Management Handbook, or contact your county noxious weed coordinator.

Mechanical: Information not available at this time.

Biological: Information not available at this time.

For more information
For more information, download our Written Findings.

 

More Photos-Click photo to enlarge
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Swainsonpea flower, leaves and stem.

 Last updated September 08, 2008