Seamless Primrose. Oenothera caespitosa, Evening Primrose Family ( Onagraceae ), Stemless Primrose. Also called Tufted Evening - Primrose, Sandlily, or White Stemless Evening primrose. We wish to thank Wikipedia, the free encyclopedia for some of the information on this page. We share images and information with Wikipedia. An evergreen to deciduous perennial dicot species of Phacelia in Arizona. Quick Notes: Height: About 10 inches. Spreading out to about 2 foot wide. Flowers: Flowers White turning pink as they wilt. Flowering Time: April - September. Leaves: Leaves are in a basal rosette. Green, fuzzy leaves. Found: Native to the USA (AZ, CA, CO, ID, MT, ND, NE, NM, NV, OR, SD, TX, UT, WA, WY). Native to Canada (AB, MB, SK); and northern Sonora, northern Chihuahua, & Baja California, in Mexico. Hardiness: USDA Zone 5a: to -28.8 �C (-20 �F) USDA Zone 5b: to -26.1 �C (-15 �F) USDA Zone 6a: to -23.3 �C (-10 �F) USDA Zone 6b: to -20.5 �C (-5 �F) USDA Zone 7a: to -17.7 �C (0 �F) USDA Zone 7b: to -14.9 �C (5 �F) USDA Zone 8a: to -12.2 �C (10 �F) USDA Zone 8b: to -9.4 �C (15 �F) USDA Zone 9a: to -6.6 �C (20 �F) USDA Zone 9b: to -3.8 �C (25 �F) USDA Zone 10a: to -1.1 �C (30 �F) Soil pH requirements: 5.6 to 6.0 (acidic) 6.1 to 6.5 (mildly acidic) 6.6 to 7.5 (neutral) 7.6 to 7.8 (mildly alkaline) 7.9 to 8.5 (alkaline) Sun Exposure: Full Sun Elevation: 1,300 - 7,500 Feet. Habitat: Growing on sandy and gravelly soils or hillsides, deserts, and low mountains; such as the Mojave Desert in California and the Sonoran Desert habitats. Miscellaneous: Flowering Photos Taken April 29, 2003. Near Lake Pleasant, Arizona.