Plant of the Week
Tufted evening-primrose (Oenothera caespitosa)
By Charlie McDonald
Tufted evening-primrose is in the evening-primrose family (Onagraceae). As the name implies, this family has many species that bloom in the evening, the flowers stay open all night, and then wilt the next day. The flowers are usually white or bright yellow and attract large night-flying insects like hawk moths (family Sphingidae). In the evening-primrose family, the flowers often have a long floral tube that holds the petals well above the base of the flower. Nectar collects in the base of the tube so only long-tongued visitors can get a nectar reward. Again, hawk moths with their long coiled tongues are perfectly adapted to reach the nectar in evening-primrose flowers.
Tufted evening-primrose is a low-growing stemless perennial with gray-green fuzzy leaves and wonderful 3-4 inch fragrant white flowers that open in the evening and close in the mid-day heat. It grows throughout the West in sunny, dry, infertile, rocky, well-drained soils.
This plant is showy, grows in poor soils, and requires little water, which makes it a perfect candidate for western xeriscape gardens. It is available as potted plants or seeds from many sources. Moderate watering will keep it blooming all summer. It must have good drainage; plants rot in heavy soils.