Page authors: Don Knoke, David Giblin
Hypericum perforatum
common St. John's wort, Klamath weed

Distribution: Occurring on both sides of the Cascades crest in Washington; Alaska to California, east across North America to the Atlantic Coast.

Habitat: Noxious weed of fields, meadows, roadsides, forest edge, wastelots, and other disturbed areas from the lowlands to near subalpine.

Flowers: June-July

Origin: Introduced from Europe

Growth Duration: Perennial

Conservation Status: Not of concern

Pollination: Bumblebees, bees, flies, wasps


Taprooted perennial with short rhizomes, the stems erect, 1-several, freely-branched, 3-8 dm. tall.


Leaves opposite, sessile, narrowly spatulate-oblanceolate to lanceolate, 1-3 cm. long, dotted with purplish-black, not clasping, but connected by narrow, wing-like structures at the base.


Inflorescence of large, many-flowered, leafy-bracteate, compound cymes; sepals 5, lanceolate, acute, 5-7 mm. long; petals 5, yellow, about twice as long as the sepals, their margins with conspicuous, black spots; stamens 75-100, attached at the base into 3 distinct groups; styles 3.


Capsule 5-8 mm. long, 3-celled, acute.

Accepted Name:
Hypericum perforatum L.
Publication: Sp. Pl. 2: 785. 1753.

Synonyms & Misapplications:
(none provided)
Additional Resources:

PNW Herbaria: Specimen records of Hypericum perforatum in the Consortium of Pacific Northwest Herbaria database.

WA Flora Checklist: Hypericum perforatum checklist entry.

OregonFlora: Hypericum perforatum information.

E-Flora BC: Hypericum perforatum atlas page.

CalPhotos: Hypericum perforatum photos.

USDA Plants: Hypericum perforatum information.

57 photographs:
Group by