Rosa sect. Caninae

Shrubs, compact, usually forming thickets; rhizomatous, rhizomes absent or relatively short. Stems erect, arching, or spreading, 7–30(–50) dm; distal branches glabrous, eglandular; infrastipular prickles paired or single, curved or appressed, rarely erect, flattened, stout, internodal prickles rare, smaller, or aciculi, sometimes absent. Leaves deciduous, rarely persistent, 4–11(–18) cm, membranous to leathery; stipules persistent, adnate to petiole, auricles flared, margins entire, rarely slightly crenate, sometimes densely glandular-ciliate, stipitate-glandular or eglandular; leaflets 5–7(–9), terminal: petiolule 5–17(–40) mm, blade ovate, obovate, orbiculate, or elliptic, sometimes oval or ovate-lanceolate, 10–45(–65) × 8–30(–50) mm, abaxial surfaces pubescent or tomentose (sometimes on midveins) or glabrous, eglandular or glandular, with or without resinous glands, adaxial pale, light, or dark green, sometimes glaucous, lustrous to dull, tomentulose or pubescent, sometimes glabrous. Inflorescences panicles, sometimes corymbs, 1–4(–7)-flowered. Pedicels erect or reflexed, stout, (5–)11–20(–35) mm, glabrous, eglandular or stipitate-glandular; bracts persistent, 1 or 2, margins glandular-serrate or stipitate- or ciliate-glandular. Flowers 2.5–5 cm diam.; hypanthium globose, ovoid, obovoid, oblong, or urceolate, glabrous, usually eglandular, base sometimes stipitate- or setose-glandular; sepals persistent or deciduous, appressed-reflexed, spreading, or erect, lanceolate or ovate-lanceolate, 10–25 × 2–5 mm, margins (outer) often deeply pinnatifid, abaxial surfaces glabrous, eglandular, densely glandular, or stipitate-glandular; petals single, pink or rose, rarely white; carpels 25–65, styles free, lanate or villous, rarely glabrous, stylar orifice 1–2.5(–3.5) mm diam., hypanthial disc flat or conic, 2–5 mm diam. Hips red to purplish or orange, globose, depressed-globose, obovoid, ovoid, oblong, urceolate, ellipsoid, or pyriform, 10–25 × 6–22 mm, glabrous, sometimes setose, eglandular or stipitate-glandular; sepals deciduous or persistent, spreading, reflexed, or erect. Achenes basiparietal.

Distribution

Introduced; Europe, Asia, n Africa, introduced also in Mexico, Central America, South America, Pacific Islands (New Zealand), Australia.

Discussion

Species ca. 20 (5 in the flora).

All species of sect. Caninae are polyploid, mostly pentaploid (2n = 35), but also triploid (2n = 21) and tetraploid (2n = 28) or all three polyploid levels for a single species, with a hemisexual, matroclinal (maternal) reproduction unlike that known for any other flowering plant (H. Nybom et al. 2000). In addition, unknown elsewhere in Rosa, apomixis appears to occur to a limited extent among Caninae species, which complicates further their reproductive anomaly (G. Werlemark 2000). Even though over 350 taxa have been described in the section, the relatively few species now recognized are highly complex groups of microspecies, and the authors agree with the editors of W. J. Bean (1970–1988, vol. 4) that no attempt should be made in modern floristic works to take account of every character-state combination. Further, those editors believed that the species of Caninae are cryptohybrids, that is, they are all products of ancient hybridizations between species that no longer exist, at least not in their primitive states.

In addition to the species treated here, Rosa obtusifolia Desvaux is marginally naturalized in California, New Mexico, and Virginia; it differs from R. canina in having hairy leaflets that are usually glandular abaxially.

Selected References

None.

Lower Taxa

Rosa canina, Rosa mollis, Rosa rubiginosa, Rosa sherardii, Rosa tomentosa

Key

1	Sepals abaxially eglandular; prickle lengths ± uniform; leaflets abaxially glabrous, rarely pubescent or tomentose on midveins, eglandular; bracts 6–18 × 4–5 mm, surfaces glabrous.	Rosa canina
1	Sepals abaxially densely glandular or stipitate-glandular; prickle lengths varying or ± uniform; leaflets abaxially usually tomentose, rarely glabrous or pubescent, usually glandular; bracts 13–21 × 4–7 mm, surfaces usually tomentose, rarely glabrous or pubescent	> 2
2	Leaflets abaxially usually densely viscid-glandular, glabrous or pubescent, glands with ripe apple scent; prickles curved or falcate.	Rosa rubiginosa
2	Leaflets abaxially usually resinous-glandular, tomentose, glands resin-scented; prickles all erect or some curved	> 3
3	Hips: sepals spreading or reflexed, deciduous after anthesis; stylar orifices 1 mm diam.	Rosa tomentosa
3	Hips: sepals usually erect, persistent after anthesis; stylar orifices 2.5–3.5 mm diam	> 4
4	Stipules 10–14 × 3–5 mm, auricles 3–4 mm; bracts 16–21 mm; sepals lanceolate, 15–20 × 3–3.5 mm; stylar orifices 2.5 mm diam.	Rosa sherardii
4	Stipules 15–20 × 5–10 mm, auricles 5–8 mm; bracts 10–12 mm; sepals ovate-lanceolate, 20–25 × (4–)5 mm; stylar orifices 3.5 mm diam.	Rosa mollis