St. Johnswort


  • Numerous, rust colored stems at base of plant
  • Pale to yellow-green leaves with small transparent dots
  • Bright yellow, 5-petaled flowers with tiny, black dots visible when held up to light; prominent stamens
  • Height 1 to 3 feet

Video Information

Weed Pictures

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Weed Information

ToxicityHumans and livestock.
ControlHand pulling/digging, mowing, biological and herbicide. Contact your county weed district or local Applicator for more information.
HabitatPastures, waste areas, roadsides and sandy, gravelly soil.
RootExtensive, deep root system.
Leaf ShapeLinar or oblong with rounded or pointed tips.
LifespanPerennial; two years or longer.
Priority 2B WeedAbundant in Montana and widespread in many counties.
Similar Looking PlantsOrnamental St. Johnswort and tansy ragwort.
Important InformationPlant contains a toxic substance which causes skin sores/rash and sun sensitivity in humans and animals. This plant is purported to have numerous medicinal properties.