“Rosa californica”
by Doreen Smith
Rosa californica is the most common wild rose in Marin and probably in California, but many old so-called occurrences
have been found by recent taxonomic experts to be other species or hybrids.
The shrubs have pink flowers and, when fruiting, red “hips,” which are commonly thought of as the fruits. Botanically speaking, however, the real fruits are hairy and seed-like, and they are contained in the urn-like fleshy red structures.
Rosa californica is the most common wild rose in Marin and probably in California, but many old so-called occurrences
have been found by recent taxonomic experts to be other species or hybrids.
The shrubs have pink flowers and, when fruiting, red “hips,” which are commonly thought of as the fruits.
Botanically speaking, however, the real fruits are hairy and seed-like, and they are contained in the urn-like fleshy red structures
which are more accurately called hypanthia. The red parts are edible and can be made into teas, syrups, and preserves, but they
must first be carefully cleaned of the inner true fruits which have choking hairs.
Flowers of native and non-native wild roses are all superficially similar, so identification keys for the species use other characters such as differences of shape of the hypanthium, sepals, leaves, and stem-prickles, and presence or absence of some glandular structures looking like tiny pin-heads.
Marin has three other native species of wild rose, R. gymnocarpa, R. spithamea, and R. nutkana var. nutkana (or a hybrid of this with R. californica), as well as three introduced species including the fragrant R. rubiginosa and scentless R. canina. The third alien Rosa, white Rosa multiflora, is not mentioned in Marin Flora, as it is presumed to have escaped from a garden. It is found on Pt. Reyes climbing over bushes by the side of the road at the top of the hill northwest of Inverness.