Common St. Johnswort

Hypericum perforatum L.

Life cycle

Multi-stemmed, shrub-like perennial.

Common St. Johnswort Young Plants
Young common St. Johnswort plant.


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.

Common St. Johnswort transparent dots
Transparent dots on common St. Johnswort leaf.


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.

Common St. Johnswort petal margin Common St. Johnswort petal margin
Common St. Johnwort flowers (left). Black dots along the petal margin of common St. Johnswort (right).


Seeds and short runners.

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The MSU IPM Program maintains this site as an access point to pest management information at MSU. The IPM Program is administered within the Department of Entomology, fueled by research from the AgBioResearch, delivered to citizens through MSU Extension, and proud to be a part of Project GREEEN.