Common St. Johnswort – Hypericum perforatum

The photo is of a common St. Johnswort plant in the field with green leaves and yellow flowers.

Common St. Johnswort – Hypericum perforatum

Hypericum perforatum L.

Clusiaceae (St. Johnswort family)

MI Status

Non-native

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 inches 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.

The photo is of common St. Johnswort flowers. These flowers have 5 petals with several black dots along the petal margins. The flowers have numerous stamens. — Common St. Johnswort flower

Opposite leaves of Common St. Johnswort. The leaves are green, elliptic-oblong to linear. — Opposite leaves of Common St. Johnswort

The photo is of young common St. Johnswort plants. — Young Common St. Johnswort plants

The photo shows common St. Johnswort flower petals. They are yellow and dotted with black glands along the margins. — Common St. Johnswort flower petal margin

The photo is of a single leaf of common St. Johnswort. The leaf is oblong with a rounded tip. You can see the leaf is dotted with numerous transparent translucent glands. — Transparent dots visible on leaf

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