Calylophus serrulatus

Species Native to Missouri
Common Name: shrubby evening primrose 
Type: Herbaceous perennial
Family: Onagraceae
Native Range: Canada and western United States
Zone: 3 to 8
Height: 0.50 to 1.50 feet
Spread: 0.50 to 1.50 feet
Bloom Time: June to July
Bloom Description: Yellow
Sun: Full sun
Water: Dry
Maintenance: Low
Flower: Showy
Tolerate: Drought

Culture

Best grown in dry, gravelly or sandy, well-drained soils in full sun. This is a taprooted plant that tolerates drought extremely well but can be difficult to transplant once established.

Noteworthy Characteristics

Calylophus serrulatus, commonly called toothed evening primrose, is native to dry prairies and mesas in western North America, particularly in the Great Plains from Canada to Texas. It is a low, shrubby, woody-based perennial which typically grows from 6-18" tall. Features narrow, lance-shaped, sessile leaves (to 2" long) which are, as both the common name and specific epithet suggest, sharply toothed. Four-petaled, stalkless, yellow sundrop flowers (to 1" wide) bloom mid-spring to mid-summer. Flowers give way to 1" long seed capsules. Additional common names for this plant include serrate-leaved evening primrose (for toothed leaves), shrubby evening primrose (for woody-based, shrubby habit), plains yellow primrose (for where it grows) and halfleaf sundrop (for leaf length and sundrop-type flower). As with other sundrops (e.g., Oenothera pilosella), the flowers of this species do not just open in the evening, but are open for the entire day. Leaves of this interesting prairie plant line up with their edges facing the intense mid-day sun as an adaptive way of minimizing water loss in a manner similar to the way that compass plant leaves (Silphium laciniatum) line up on a north-south axis for the same purpose.

Genus name is in reference to the lobes on the calyx.

Specific epithet means with small saw-toothed leaves.

Problems

No serious insect or disease problems.

Garden Uses

Rock gardens, dry border fronts or prairie areas.