7a. Rosa Linnaeus subg. Hesperhodos (Cockerell) Cockerell ex Rehder, Man. Cult. Trees ed. 2. 451. 1940.
Hesperhodos Cockerell, Nature 90: 571. 1913
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.
Species 2 (2 in the flora): sw, sc United States, nw Mexico.
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.
SELECTED REFERENCE Lewis, W. H. 1965. Monograph of Rosa in North America. V. Subgenus Hesperhodos. Ann. Missouri Bot. Gard. 52: 99–113.