Oenothera biennis

Native

Dry soils. Prairies, fields, roadsides, and waste places.

June to October

Yellow

24″ to 72″

Fully open flowers are 1″ to 2″ wide.

The lemon-scented flowers have a unique, cross-shaped stigma.

The oblong, blunt-tipped seed capsules begin to split open in October.

Cleland’s evening primrose (Oenothera clelandii) is a smaller plant, no more than 40″ in height. The flowers are smaller and have diamond-shaped petals. The seed capsules are smaller and are curved.

Cut-leaved evening primrose (Oenothera laciniata) is a short plant, reaching only 18" at maturity. The leaves are lobed.

Northern evening primrose (Oenothera parviflora) has smaller flowers, no more than one inch wide.

Nuttall’s evening primrose (Oenothera nuttallii) has white flowers.

Perennial evening primrose (Oenothera perennis) is a shorter plant, reaching only 24″ at maturity. It has smaller flowers, ⅓″ to ¾″ wide.

Rhombic evening primrose (Oenothera rhombipetala) flower has diamond-shaped petals.

Toothed evening primrose (Calylophus serrulatus) is a much shorter plant, reaching only 24″ at maturity. It is usually found with clustered stems, which may be woody at the base. The leaves are toothed, and are linear or oblong and narrow.

The family name refers to the fact that the flowers are partially to fully closed during the day, open in the evening, and close at noon. The plants are pollinated by Hawk Moths or Sphinx Moths, which feed on their nectar at night.