Page authors: Don Knoke, David Giblin
Hypericum perforatum
common St. John's-wort, Klamath weed
WTU specimens
Other herbaria

Distribution: Widespread on both sides of the Cascades crest in Washington; widespread throughout much of North America.

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

Conservation Status: Not of concern

Description:
General:

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

Leaves:

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.

Flowers:

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.

Fruits:

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

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

Synonyms & Misapplications:
(none provided)
Infraspecies:
ssp. perforatum – common St. John's-wort, Klamath weed
Additional Resources:

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

WA Flora Checklist: Hypericum perforatum checklist entry.

E-Flora BC: Hypericum perforatum atlas page.

CalPhotos: Hypericum perforatum photos.

USDA Plants: Hypericum perforatum information.

45 photographs:
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