Plant Of The Month: Calylophus
Calylophus is widely distributed throughout the South Central US, from Texas, Louisiana and New Mexico, north to Colorado and Kansas. It is found in sandy or rocky soils in plains, woodland edges and along roadsides. This is a great plant for a rock garden, as it needs good drainage, sunlight and heat.
It begins blooming as early as March with 2” clear lemon yellow flowers and continues less prolifically throughout the summer until fall. The plant itself is upright and bushy, usually less than 2’ tall, with narrow, spiny-toothed leaves that remain green in mild winters. Over time the base of the plant can get woody.
The flowers of Calylophus somewhat resemble Missouri Primrose (Oenothera missouriensis). Blooms of both open in the evening. However, Calylophus flowers remain open through the day whereas those of Missouri Primrose close about noon (hence the name Evening Primrose). Calylophus also has raised ribs on the green sepals that enclose the flower bud, giving it a squarish appearance and leading to another common name, Squarebud Primrose.
The blooming period can be prolonged by picking off old blooms and giving it some supplemental water in summer. It can be pruned back to 8” in early winter to keep it in shape. It is considered only moderately deer resistant. Calylophus is available in nurseries that feature native plants, or it can be propagated from seeds planted in the fall or cuttings from new growth in the spring.
Text by John Siemssen. Photo by Joseph A. Marcus, Wildflower Center