Common St. Johnswort – Hypericum perforatum

Common St. Johnswort

Hypericum perforatum L.
Clusiaceae (St. Johnswort family)

Life cycle

Multistemmed, shrublike perennial.

Leaves

Opposite, narrow oval to oblong leaves have round to pointed tips and entire margins, and attach directly to the stem. Leaves are covered with small, transparent dots when viewed against the light.

Stems

Erect with numerous branches and up to 3 feet tall. Herbaceous stems are often reddish in color and become woody at the base with maturity.

Flowers and fruit

Bright yellow to orange-yellow flowers with five petals are approximately 0.75 inch wide, often with several black dots along the petal margins. Fruit are capsules with three cells containing numerous dark brown to black, cylinder-shaped seeds.

Reproduction

Seeds and short runners.

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Common St. Johnswort in a field
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Common St. Johnswort flower
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Opposite leaves of Common St. Johnswort
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Young Common St. Johnswort plants
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Common St. Johnswort flower petal margin
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Transparent dots visible on leaf

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Plant & Pest Diagnostics

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