common St. Johnswort
Hypericum perforatum L.


Hypericum perforatum is a perennial, rhizomatous herb that can reach 4 ft. (1.2 m) in height.
Leaves are opposite, sessile, elliptic, 0.4-1.2 in. (1-3 cm) long and dotted with many pellucid glands.
Flowering occurs from June to September, when bright yellow flowers develop at the tips of the stems. Flowers have five petals and many stamens. Petals typically have black glands along the margins.
The fruits are three-chambered capsules with three persistent styles.
Ecological Threat
Hypericum perforatum has been used to treat mild depression, but has been shown to cause hyper photosensitivity. Plants inhabit rangelands, pastures, roadsides and forest clearings. St Johnswort is native to Europe. Hypericum perforatum may be poisonous to cattle in large doses.


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EDDMapS Distribution

EDDMapS Distribution - This map is incomplete and is based only on current site and county level reports made by experts, herbaria, and literature. For more information, visit

State Regulated List

State Regulated List - This map identifies those states that list this species on their regulated list. For more information, visit

Taxonomic Rank

Kingdom: Plantae
Phylum: Magnoliophyta
Class: Magnoliopsida
Subclass: Dilleniidae
Order: Theales
Family: Clusiaceae
Genus: Hypericum
Subject: Hypericum perforatum L.

Synonyms and Other Names

Other Common Names:
Klamathweed, St. John's wort


Plants - Forbs/Herbs