common evening-primrose (Oenothera biennis) — identification, habitat & look-alikes

Common evening-primrose is a North American wildflower found in fields and along roadsides. Its yellow flowers open at dusk, drawing night-flying moths and early-morning bees. Common evening-primrose grows a circle of leaves close to the ground in its first year and a tall flowering stem in its second year.

Appearance

Growth form: In its flowering year, an upright hairy stem usually reaches 3–5 ft (0.9–1.5 m).
Leaves: The first-year has lance-shaped, shallow-toothed leaves; stem leaves are alternate and nearly stalkless.
Flowers: Each bowl-shaped flower is 1–2 in (2.5–5 cm) wide, with four pale yellow petals and a cross-shaped tip at its center.
Flowering time: Across much of the eastern United States, it blooms from June through September.
Fruit: Narrow split when ripe and can release many seeds.

Look-alikes

cutleaf evening primroseOenothera laciniata

Cutleaf evening primrose (Oenothera laciniata) often branches from a lower, spreading stem and has wavier, more deeply toothed leaves. Common evening-primrose usually stands upright and carries its yellow flowers near the top.

Why they get mixed upBoth have four yellow petals and grow in open, disturbed soil.

hairy evening primroseOenothera villosa

Hairy evening primrose (Oenothera villosa) has a visibly hairier, often grayer flower stalk. These close relatives can be hard to separate in ordinary photos, so check close photos of the flower stalk and buds.

Why they get mixed upBoth have tall stems and yellow evening flowers in North America.

Where it lives

Typical habitats: fields
prairies
roadsides
disturbed ground
Range: It is native across much of eastern and central North America and occurs through most of the United States, with scattered western populations.
Preferred conditions: It grows best in full sun and well-drained sandy, gravelly, or loamy soil, and it tolerates some drought.
Flowering: Flowers Jun–Sep
Flowers Jun–Sep

Behavior

Activity: Flowers open at dusk, remain open through the morning, and close as the day becomes hot.

Life cycle

Reproduction: Plants usually die after setting seed, while new seedlings continue the patch.

Growing it

Care: It fits naturalized and pollinator plantings but self-seeds freely and can look weedy in a formal bed.

Conservation

IUCN Red List: NENot EvaluatedNot yet assessed

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