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Oenothera primiveris - desert evening primrose

Scientific Family
Onagraceae
Other common names
large yellow desert primrose
yellow-flower desert evening-primrose
Plant type
Forbs and Subshrubs
Origin
Native
Lifecycle
Annual
Height
4 to 8 inches
Riparian
No

Leaves form as a basal rosette; flower stalks also emerge at ground level. Leaves and flower stalks have a dense covering of short hairs. Some of the hairs have reddish bases; sepals may have glands.

Annual, often develops stout leafy stems; leaves narrow and long, mostly pinnatifid into toothed or rounded lobes; flowers have 4 yellow notched petals that age red, mostly open late afternoon, stigmas have 4 narrow lobes; fruits round in cross-section.

Habitat

Flat desert habitats, including creosote bush scrub, Joshua tree woodland, and Pinyon-juniper woodland.

Plant Community
Desert Scrub
Grasslands
Interior Chaparral
Pinyon Juniper Woodlands
Low elevation
0
High elevation
4500

Flower Characteristics

Each flower has heart-shaped petals up to 2 inches in length which fade to red with age; opens at dusk and closes the following morning.

Flower color
Yellow, ages red
Flower shape
Regular
Tubular
No
First bloom month
March
Last bloom month
May
Flower clusters
None

Leaf and Stem Characteristics

Nearly stemless above ground; blades vary between large and small; 2 inches to 11 inches long; larger blades are 1 to 2-3/4 inches wide; lance-like leaves divided into toothed or rounded lobes, typically narrow.

Leaf type
Simple
Leaf color
Green, grayish-green
Leaf shape
Pinnatifid
Leaf margin
Toothed
Leaf attachment
Basal
Leaves clasp
No
Leaf hairs
Leaves & stems
Spines
No

Fruit and Seed Characteristics

Ovary and capsule densely hairy with spreading white hairs; capsules 1 to 1-3/4 inches long; 1/4 inch wide at base; thick and woody; upright and straight; 4-angled; tapering to narrow tip.

Fruit type
Capsule
Fruit color
Brown

Brown, 1/8 inch.