Hooker's Evening Primrose
Oenothera elata
(Oenothera hookeri)
Photographed along Mesquite Wash, Maricopa Co., Arizona. June 2008.
PERENNIAL: Robust herbaceous annual or perennial apparent from late spring through
autumn. One or a few erect stems generally a meter
or more tall.
FLOWERS: Large lemon-yellow petals fade in the morning after remaining open
through the night. Color changes to peach-orange as the flower wilts. Usual
evening primrose formula of 4 sepals, 4 petals and 8 stamens. Blooms during hot months.
LEAVES: Elliptical leaves are relatively large and generously distributed
along the stems. Alternate on the stem and with small teeth along the margins.
RANGE: Restricted to moist, riparian habitats in the Sonoran Desert in
Arizona and Mexico. Ranges across the Western United States.
FRUIT: Four sided capsule with many seeds is positioned well below the
flower petals joined by a long collar, the hypanthium.
UNARMED. No spines/thorns.