Rosa subg. Hesperhodos
Man. Cult. Trees ed. 2, 451. 1940.
Leaves 1.5–3 cm; leaflets 3–7, margins deeply incised or broadly crenate, sometimes serrate, terminal: petiolule 0.5–4 mm, blade oval, suborbiculate, obovate, or deltate, base cuneate. Inflorescences 1(–3)-flowered. Pedicels: bracts present or absent. Flowers: hypanthium subglobose to globose or cupulate, densely pubescent or glabrous, setose or not, glandular or eglandular; carpels 10–110 (average 65), styles free, pilose, stylar orifice 2–5 mm diam., rims 0.5–1 mm wide, hypanthial disc absent. Hips leathery, setose.
Distribution
sw, sc United States, nw Mexico.
Discussion
Species 2 (2 in the flora).
A phylogenetic analysis using plastid DNA sequences suggests that subg. Hesperhodos is sister to the rest of Rosa, but with weak support (A. Bruneau et al. 2007). This contrasts with analyses indicating that R. persica Michaux of subg. Hulthemia (Dumortier) Focke is sister to the remainder of the genus (S. Wu et al. 2001; V. Wissemann and C. M. Ritz 2005). A more compelling resolution might be possible once the related and more variable R. stellata is examined phylogenetically.