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St. Johnswort

Hypericum perforatum

Plant Description

Stems are branching with yellow flowers, petals edged with black dots; opposite leaf arrangement.

Plant Details

Life Forms
ODA Listing
Soil and Moisture Conditions
Suggested Actions
Shade Preference
Mature Height 1-2.5'
Distribution Widespread in Oregon
Control Hand pulling is only recommended for very small patches. Mowing is inneffective. Tillage may be used. Several biological control agents have been released.
Reproduction and Spread Spreads by seeds and rhizomes. Produces 15,000 to 34,000 seeds per plant; seeds may remain viable for more than 50 years.
Introduced First reported in PA in 1696. Carried to Oregon between 1840-1850.
Look Alikes cinquefoil, buttercup
Impact This plant is toxic to livestock such as cattle, sheep and horses, can cause severe skin lesions and hypersensitivity to sunlight.
More Info
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