Rockroses, in the genus Cistus, are mainstays in the drought-tolerant gardens of recent years. They hail from the Mediterranean and are well-adapted to the same sort of climate regime here in Southern California, where the cool, usually rainy season of winter gives way to a dry spell of many months through late spring and early fall. Even in coastal areas with more marine moisture, these handsome shrubs perform well, adding evergreen foliage and bright floral displays to the landscape.
Less well-known are a couple of their close relatives that are equally adaptable and lovely to look at. Also native to the Mediterranean region — Spain, Portugal, France, and North Africa — they thrive on poor rocky soil. There is one species, Helianthemum nummularium, from which many selections and hybrids have been developed. Most are low-growing shrubs, reaching only six to eight inches in height, but spreading to as much as three feet across. The leaves are small and may be gray beneath and green above, or gray overall. It is the one-inch diameter flowers that display the family ties to rockroses. Five crinkled petals radiate from a central tuft of yellow stamens. There are even a few with doubled petals. Shades of color from white to yellow, pink to rose, and peach to salmon are displayed in profusion. Even though individual flowers last but one day, continual production of new buds from spring through early summer makes them handsome candidates for the front of the flower bed. Plant in full sun to partial shade in well-drained soil, and don’t water excessively. Not generally in cultivation is the California native sunrose, H. scoparium. It grows in the dry slopes of the foothills in both the Coast Ranges and the Sierra Nevada.
An equally unpronounceable genus in this family is Halimium. H. atriplicifolium is readily available. This sturdy evergreen shrub grows to three feet tall by about five feet wide and is clothed in gray-green leaves. The stems are covered in red hairs, giving even more interest. The bright yellow flowers are quite similar to those of its cousins. Some of the other species in this genus also sport the telltale blotch at the base of each petal that most rockroses do. Look also for H. lasianthemum, H. ocymoides, or H. umbellatum online or in specialty nurseries. All require sun and well-drained soil. A light shearing after bloom time will improve next year’s shape.
One feature of the flowers in this family that isn’t evident to the naked eye is the presence of a nectar disk. This floral organ makes all of these species very attractive to a variety of insects. In fact, that dark blotch on the petals of many species may act like a bull’s-eye, leading insects straight to the source. Bees, hover flies, and even butterflies and moths will pay a visit to the blossoms for their sweet reward. This makes them excellent plants to include in a butterfly garden as well as useful in attracting beneficial insects to the landscape.
Add the traits of being naturally pest-free, unlikely to succumb to fungal pathogens, and generally unpalatable to four-footed beasts such as deer and rabbits, and it’s clear that sunroses should be on every gardener’s list.
Virginia Hayes, curator of Ganna Walska Lotusland, will answer your gardening questions. Address them to Gardens, The Independent, 122 W. Figueroa St., S.B., CA 93101. Send email to firstname.lastname@example.org.