By Bobbie Stephenson.
San Diego County is home to three species of wild roses: California wild rose (Rosa californica), bald-hip rose (Rosa gymnocarpa), and small-leaved rose (Rosa minutifolia). They all have pink, and rarely white, five-petaled flowers with many stamens. Spreading by runners, these subshrubs form dense thickets of three to six feet tall.
The most common is the California wild rose, which grows naturally in much of California and has smooth fragrant hips that are good for making tea. This rose will take some drought but prefers some moisture. In San Diego County, it grows along the banks of streams and rivers and is an important plant for wildlife.
In the far north of San Diego County, at elevations above 5000 feet, like on the flanks of Mount Palomar, the slender delicate bald-hip rose grows. The stems are bristled rather than thorned. Though roses have inferior ovaries, meaning that the fruit develops below the floral parts (i.e. petals and sepals) and these dried parts usually remain on the fruit, the sepals in the bald-hip rose are deciduous, making the fruit (hips) look “naked”, therefore the specific name gymnocarpa (naked fruit). This species grows in many northern and central California counties, but only at a few locations in southern California. Seeds can be collected and sown outdoors in the fall, though germination can take up to two years.
Of particular interest in San Diego County is the small-leaf rose, which is native to the chaparral of northern Baja California where wild populations are extant, and San Diego County, where it is now extinct in the wild. The last known occurrence in southern California was one clump at the head of a canyon on Otay Mesa; this thicket of small-leaved rose has now been lost to development. Before grading began, this individual plant covering about 100 square feet was salvaged and propagated so it could be used in landscaping the slopes of the development and so that its genetic makeup would not be lost. The small-leaf rose is the earliest flowering (from February through April) of native California roses, probably because it grows in the most arid parts of the state, where spring arrives early.
Bobbie Stephenson is a local botanist and the current president and newsletter editor of the San Diego Chapter of the California Native Plant Society.