Swainsonpea (Fremont County Declared Noxious Weed)

Swainsonpea (Fremont County declared weed)

  • Sphaerophysa salsula
  • Fabaceae (Pea family)

Swainsonpea was introduced from Asia and is commonly found in some western states including Wyoming, infesting roadsides, along fences and other areas. A Declared Noxious Weed in Fremont County, it is a potential threat to alfalfa and grain producing areas.

Growth Habit: Creeping, upright perennial, many branched.

Leaves: Compound, composed of numerous opposite leaflets which are oval and covered with hair.

Flowers: Orange-red about 1/4 to 1 inch in length. Flowers from May to July. Numerous seeds are formed in bladder-like translucent pods.

Roots: Creeping, lateral roots. Reproduces by root and seed.

Status: County Declared Noxious Weed, Category 4. Widespread infestation. Control and maintenance of current weed infestations.

Control: Herbicides can be effective. FCWP offers a 40 percent Cost Share on chemicals for controlling this species. Contact your local weed and pest office for further treatment recommendations.

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