Onagraceae : Calylophus serrulatus
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Family Name
Onagraceae
Common Name
Narrow evening primrose
Description
Calylophus serrulatus is a perennial herb with few to many simple to branched, decumbent to erect stems, 5-80 cm long. The simple, alternate leaves are linear to lanceolate, 1-10 cm long and 1-12 mm wide, smooth to slightly hairy on top and generally hairy on the under surface. The blades are sessile to semipetiolate, the leaf tapering to the base and having a pointe tip, with margins that are entire to toothed. The 4-merous flowers are axillary in the upper parts of the stems. The sepals are 1.5-9 mm long and 2-6 mm wide, distinctly keeled, hairy below, with free tips 1-4 mm long. The 4 yellow petals are 5-20 mm long and about as wide. There are 2 series of stamens, one attached to the sepals and the other the petals, the former longer than the latter, and the stigma is ~2 mm wide in the center of the flower. The fruit is a capsule, 10-30 mm long and 1-3 mm wide. Yellow sundrops bloom from May into September on roadsides in rocky to sandy prairies and open woodlands in much of South Dakota.
Horticulture Notes
Seed collection: Collect seeds when the capsules when the capsules turn brown.
Germination: Seeds require a 90-day moist cold treatment for spring planting. Fall sowing generally provides good results.
Soils: Tolerates a wide range of soils, including clays, but requires well-drained conditions.
Light: Full sun to light shade.
Water: Dry to medium wet conditions, as long as the soils are well drained.
Additional Notes
Plains evening primrose is drought resistant and heat tolerant, well-suited for native plant xeriscapes and rock gardens. Its foliage and flowers are attractive and are an important source of nectar for bees and butterflies. The plant also serves as a host for the larvae of some native butterfly species. This member of Onagraceae is unusual in that it blooms during the day whereas most primrose flowers open in afternoon or evening, making it more visible in most gardens.