Hypericum perforatum L.
Family: Hypericaceae
common St. John's-wort, Klamath-weed, St. John's-wort
Hypericum perforatum image
Christopher Noll  
Etymology: Hypericum: ancient Greek name derived from hyper, "above," and eikon, "picture," from old practice of placing flowers above an image in the house to ward off evil spirits at the midsummer festival of Walpurgisnacht, which later became feast of St. John
Plants: erect, perennial, 2'-3' tall forb with many leafy branches; stems with a sharp ridge below the base of the leaves
Leaves: stalkless, small, 1/4" wide leaf drawing
Flowers: yellow, 5-parted, 5/8"-1" wide, stalked, petals with black dots near the edges; inflorescence a many-flowered, rounded to flat, compound, branched cluster (cyme); blooms June-Sept.
Fruits: 3 chambered capsule fruit drawing
Habitat: disturbed sites, fields, roadsides
Hazardous: Careful, this plant is hazardous!
Invasiveness: Invasive - Eradicate!
Conservation Status: Introduced - naturalized; ecologically invasive