(2018)  
 
Rosa arkansana Porter in T. C. Porter and J. M. Coulter, Syn. Fl. Colorado. 38. 1874.
Prairie rose
Rosa alcea Greene; R. arkansana var. suffulta (Greene) Cockerell; R. conjuncta Rydberg; R. suffulta Greene

Shrubs, forming hedge clusters. Stems erect, slender or stout, 6–15 dm, openly branched; bark dull red to purplish red, glabrous; infrastipular prickles rarely present, internodal prickles densely mixed with aciculi ˂to stem apices˃, erect, terete, 1–3(–4) × 0.5–2 mm, base rarely extending to 3 mm, smallest often gland-tipped, aciculi rarely absent. Leaves 5–10(–16) cm; stipules 18–24 × 4–7 mm, auricles flared, 2.5–4(–7) mm, margins undulate, coarsely or shallowly glandular-serrate, surfaces glabrous or puberulent, eglandular; petiole and rachis sometimes with pricklets, sometimes with sparse aciculi, pubescent, sometimes glabrous, rarely stipitate-glandular; leaflets (5–)7–9(–11), terminal: petiolule 4–12 mm, blade obovate, sometimes elliptic, 15–40 × 8–20 mm, membranous, margins 1(–2+)-serrate, teeth 8–16 per side, eglandular, rarely gland-tipped, apex acute, abaxial surfaces pale green, pubescent, sometimes glabrous, eglandular, adaxial green, ± glaucous, dull, sometimes pubescent (especially along midveins). Inflorescences corymbs, 1–6(–16)-flowered. Pedicels erect, slender, 10–20 mm, glabrous, eglandular; bracts 1 or 2(or 3), broadly lanceolate, 11–20 × 5–8 mm, margins entire, eglandular, surfaces glabrous, eglandular. Flowers 3.3–4 cm diam.; hypanthium globose, 5–6.5 × 4–5.5 mm, glabrous, eglandular, neck (0–)0.5–1.5 × 2 mm; sepals spreading to erect, lanceolate, 11–20(–30) × (1.5–)3–4 mm, tip 3–7 × 0.5–1 mm, margins pinnatifid or entire, abaxial surfaces glabrous, stipitate-glandular or eglandular; petals single, rarely double, pink or rose, sometimes fading white, rarely white, 22–26 × 21–30 mm; ˂stamens 120˃; carpels 26–43, styles exsert 1.5–2 mm beyond stylar orifice (1.5 mm diam.) of hypanthial disc (3 mm diam.). Hips dull orange-red, globose, subglobose, or oblong, 10–11 × 7.5–13 mm, fleshy, glabrous, eglandular, rarely stipitate-glandular, neck 0–2 mm; sepals persistent, erect at hip maturity. Achenes basiparietal, 12–15, dark buff, ˂ellipsoid˃, 4.5–5 × 2.5 mm. 2n = 28.
Flowering May–Jul. Rocky slopes, dry hillsides, prairies, bluffs, open woods, grassy roadsides; 200–2100 m; Alta., B.C., Man., Ont., Sask.; Ark., Colo., Ill., Ind., Iowa, Kans., Maine, Mich., Minn., Mo., Mont., Nebr., N.Mex., N.Y., N.Dak., Ohio, Okla., S.Dak., Tex., Wis., Wyo.
Rosa arkansana is one of the more invasive indigenous roses in North America. Collections from Maine, Massachusetts, New York, North Carolina, Ontario, Quebec, and Vermont, where nativity is unknown, are introductions that by and large are ephemeral. In other states where R. arkansana is native, disjunct populations may be either introduced or ephemeral, including those in Illinois, Indiana, Michigan, Ohio, and north-central Texas in disturbed areas. It is indigenous from northeastern British Columbia to Manitoba, east to Ohio, western Missouri, northeastern New Mexico, and Colorado in prairies and plains, and within the eastern Rocky Mountains of the North American Prairies Province (A. Cronquist 1982).
Rosa arkansana possibly arose from the diploid R. blanda and R. woodsii complex as an autopolyploid (S. Joly et al. 2006). It hybridizes with R. carolina; the hybrids are known as R. × medioccidentis W. H. Lewis...
In a breeding program initiated by Agriculture-Canada to establish winter hardy roses for the Canadian prairies, the best results were obtained by crossing Rosa arkansana and, sometimes, R. spinosissima with floribundas and hybrid teas to produce new cultivars such as ‘Prairie Joy’ (L. M. Collicutt 1992) and ‘Winnipeg Parks’ (Collicutt 1992b).

 

(2018)  
 
Rosa blanda Aiton, Hort. Kew. 2: 202. 1789.
Meadow or smooth rose, rosier inerme
Rosa johannensis Fernald; R. rousseauiorum B. Boivin; R. subblanda Rydberg; R. williamsii Fernald
Description...

M. Mercure and A. Bruneau (2008) described and genetically confirmed spontaneous hybrids between Rosa blanda and R. rugosa forming colonies along the St. Lawrence Estuary, Quebec. Analyses indicated that most of the hybrids were first generation; second generation and backcrosses were also detected. This is a recently established hybrid zone with the potential for introgression of the aggressive R. rugosa into native R. blanda and thereby a serious threat to the integrity of the native species.
A. Bruneau et al. (2007) found that, within Rosa blanda, previously recognized segregate species (R. johannensis, R. rousseauiorum, R. subblanda, R. williamsii) should not be considered specifically distinct from R. blanda, although populations representing R. williamsii might be worthy of subspecific recognition

(2018)  
 
Rosa blanda and R. palustris differ by: branch armature (R. blanda unarmed or with sparse prickles or aciculi, R. palustris with stout, curved infrastipular prickles or unarmed); length of each auricle (R. blanda average 4.8 mm, R. palustris average 2.6 mm); petioles and rachises with pricklets (R. blanda rare, R. palustris common); leaflet serrations (R. blanda serrate, acute, teeth 10–26 per blade side, R. palustris serrulate, slightly blunt, teeth 20–30 per blade side); pedicels stipitate-glandular (R. blanda eglandular, R. palustris almost always); hypanthia stipitate-glandular (R. blanda eglandular, R. palustris almost always); inflorescences corymbs (R. blanda rare, R. palustris common).

(2018)  
 
Rosa bridgesii Crépin ex Rydberg, Bull. Torrey Bot. Club. 44: 83. 1917.(name conserved)
Sierran ground rose
Rosa gymnocarpa Nuttall var. pubescens S. Watson; R. spithamea var. solitaria L. F. Henderson; R. spithamea S. Watson var. subinermis Engelmann
Description...

In the phylogenetic analysis by A. Bruneau et al. (2007), Rosa bridgesii and R. spithamea comprise a distinct clade more closely related to Asian species than to others from western North America.
Rosa bridgesii has been conserved against R. calvaria Greene, R. covillei Greene, R. crenulata Greene, R. myriadenia Greene, and R. yainacensis Greene (B. Ertter 2007b). Only R. calvaria and R. crenulata are unambiguous synonyms of R. bridgesii; the taxonomic identity of the other names remains unresolved and may involve hybridization with other species.
On the basis of pollen size, E. W. Erlanson (1931) believed that material falling within the current circumscription of Rosa bridgesii was tetraploid (2n = 28). In a subsequent paper (1934), she reported a diploid somatic count (2n = 14) for R. calvaria, a synonym of R. bridgesii. Recent flow cytometry indicates a tetraploid condition for the sampled specimen of R. bridgesii (A. Bruneau et al., unpubl. data). It is possible that both ploidy levels are present within the species.

(2018)  
 
Rosa californica Chamisso & Schlechtendal, Linnaea. 2: 35. 1827.
California rose
Rosa aldersonii Greene
Description

(2018)  
 
Rosa carolina Linnaeus, Sp. Pl. 1: 492. 1753.
Carolina or pasture rose, rosier de Caroline
Shrubs or subshrubs, forming scattered populations. Stems spreading and weak, sometimes erect, slender, 3–10(–13) dm, openly branched; bark dull reddish brown, glabrous; infrastipular prickles usually paired, erect, sometimes declined, rarely curved, flat, subulate, (2–)3–9 × 1.5–3 mm, ˂base glabrous˃, internodal prickles sparsely or densely mixed with aciculi, stipitate glands and smaller internodal prickles. Leaves 5–10(–16) cm; stipules 10–18(–23) × 2–3 mm, auricles flared, 2–4 mm, margins entire or subserrate, eglandular or finely stipitate-glandular, surfaces glabrous, rarely puberulent, eglandular; petiole and rachis sometimes with pricklets ˂3 mm˃, aciculi few, glabrous, rarely pubescent, rarely stipitate-glandular; leaflets (3–)5–7(–9), terminal: petiolule 4–11 mm, blade ovate, elliptic, or lanceolate, 18–50 × 9–28 mm, membranous, base cuneate, margins 1–2+-serrate, teeth 8–14(–18) per side, eglandular or gland-tipped, apex acute to acuminate, rarely obtuse, abaxial surfaces pale green, glabrous, rarely pubescent, eglandular or glandular, adaxial usually green, dull, rarely slightly lustrous, glabrous. Inflorescences corymbs, 1–3(–6)-flowered. Pedicels erect, slender, 5–19 mm, glabrous, sparsely to ± densely stipitate-glandular, sometimes eglandular; bracts 2, lanceolate, 10–17 × 2–4 mm, margins entire, usually eglandular, surfaces with sparse hairs, stipitate-glandular. Flowers 3–5.5 cm diam.; hypanthium globose or ovoid, 4–6(–8) × 3.5–5(–8) mm, glabrous, ± densely to sparsely stipitate-glandular, sometimes eglandular, neck (0–)0.5–1 × 2 mm; sepals reflexed, sometimes spreading, lanceolate, 10–22 × 2–3 mm, tip 2–10 × 0.5–1 mm, margins pinnatifid or entire, abaxial surfaces rarely puberulent, stipitate-glandular, rarely eglandular; petals single, pink, 15–24 × 13–19 mm; ˂stamens 105˃; carpels 32–46, styles exsert 1 mm beyond stylar orifice (1.5–2 mm diam.) of hypanthial disc (4–5 mm diam.). Hips red or orange-red, globose or depressed-globose, rarely ellipsoid, 7–14 × 6–15 mm, fleshy, glabrous, densely to sparsely stipitate-glandular, sometimes eglandular, neck 0–0.5 × 5–6 mm; sepals early deciduous, spreading to reflexed. Achenes basal, 2–6(–10), tan, 4–5 × 2.5–3 mm.
Subspecies 3 (2 in the flora): North America, ne Mexico.
Rosa carolina is a polymorphic allotetraploid derived from diploids found in eastern North America (S. Joly et al. 2006). Two nothospecies representing presumptive secondary hybridization and introgression are R. ×medioccidentis W. H. Lewis (R. arkansana × R. carolina) in Iowa, eastern Kansas, and western Missouri, and R. ×novae-angliae W. H. Lewis (R. carolina × R. virginiana) of New England, infrequently south to the District of Columbia, nearby Virginia, and New Jersey (W. H. Lewis 2008).
The Menominee of Wisconsin once ate hips of Rosa carolina to treat gastrointestinal problems (H. I. Smith 1923).
Subspecies mexicoensis W. H. Lewis is found in the Sierra Madre Oriental of northeastern Mexico (Coahuila, Nuevo León, Tamaulipas).
SELECTED REFERENCE Lewis, W. H. 2008. Rosa carolina (Rosaceae) subspecies and hybrids in eastern and midwestern United States, Canada, and Mexico. Novon 18: 192–198.

(2018)  
 
Rosa carolina Linnaeus subsp. carolina
Rosa aucuparia Rydberg; R. carolina var. grandiflora (Baker) Rehder; R. carolina var. villosa (Best) Rehder; R. humilis Marshall; R. lyonii Pursh; R. parviflora Ehrhart; R. serrulata Rafinesque
Description

(2018)  
 
Rosa carolina Linnaeus subsp. subserrulata (Rydberg) W. H. Lewis, Novon. 18: 195. 2008.
Rosa subserrulata Rydberg in N. L. Britton et al., N. Amer. Fl. 22: 500. 1918; R. palmeri Rydberg; R. rudiuscula Greene; R. texarkana Rydberg
Stems erect, robust; infrastipular prickles subulate or stout, mixed with dense, shorter internodal prickles, aciculi, and sparse stipitate glands to apices. 2n = 28.
Flowering May–Jul. Dry wooded slopes, hillside thickets, rocky hills, upland woods, cherty upper slopes, sandstone glades, prairies; 100–1100 m; Ont.; Ala., Ark., Ga., Ill., Ind., Iowa, Kans., La., Md., Mich., Miss., Mo., N.C., Okla., Pa., S.C., Tenn., Tex., Va., W.Va., Wis.
Subspecies subserrulata is distinguished by relatively short, stout, erect stems armed with paired, subulate or stout, long, infrastipular prickles together with shorter prickles, aciculi, and stipitate glands to stem apices. It is most common in the Midwest with an epicenter in drier habitats of the Ozark Plateau, where it is particularly common in Arkansas, eastern Kansas, Missouri, eastern Oklahoma, and northeastern Texas. This range corresponds to the Illinoian Floristic Subprovince and, in part, the Appalachian Subprovince, where both subspecies occur.

(2018)  
 
Rosa foliolosa Nuttall ex Torrey & A. Gray, Fl. N. Amer. 1: 460. 1840.
White prairie rose
Rosa ignota Shinners
Shrubs, forming thickets or not. Stems erect to deflexed, 3–6 dm, densely branched; bark dull reddish brown, sometimes green, glabrous; infrastipular prickles paired, erect, subulate, 2–5 × 0.5–1 mm, ˂base glabrous˃, internodal prickles or aciculi rare, sometimes absent. Leaves 3–7 cm; stipules 6–14 × 1.5–4 mm, auricles flared, 2–3 mm, margins entire or glandular-serrate, eglandular, surfaces glabrous, rarely puberulent, eglandular; petiole and rachis with pricklets, usually glabrous, stipitate-glandular; leaflets (5–)9(–11), terminal: petiolule 1–4(–6) mm, blade lanceolate to narrowly elliptic, 14–25 × 3–7 mm, membranous, base long-cuneate, margins 1-serrate, ˂gland-tipped or eglandular˃, teeth 9–15 per side, gland-tipped, apex acute, abaxial surfaces light green, glabrous, eglandular, ˂exserted midveins sometimes with sparse pricklets, pubescent, stipitate-glandular˃, adaxial deep green, lustrous, glabrous. Inflorescences corymbs, 1(–5)-flowered. Pedicels erect, slender, 2–8 mm, glabrous, stipitate-glandular; bracts 2, lanceolate, 8–12 × 3–4 mm, margins entire, few stipitate-glandular, surfaces glabrous, eglandular. Flowers 3.5–4.5 cm diam.; hypanthium subglobose, globose, or ovoid, 4–4.5 × 2.5–4 mm, glabrous, usually densely stipitate-glandular, neck absent; sepals reflexed or spreading, lanceolate, 13–20 × 2–3 mm, tip 3 × 0.5 mm, margins pinnatifid, abaxial surfaces glabrous or puberulent, stipitate-glandular; petals single, white, rarely pink, 17–28 × (6–)10–18 mm; carpels 20–32, styles exsert 1–1.5 mm beyond stylar orifice (1.5–2 mm diam.) of hypanthial disc (3–4 mm diam.). Hips dull red, globose to depressed-globose, rarely urceolate, 9–10 × 7–9 mm, leathery, glabrous, densely stipitate-glandular, neck absent or insignificant; sepals deciduous, spreading to erect. Achenes mostly basal, 8–12, tan, 4(–5) × 1.5–2 mm. 2n = 14.
Flowering May–Jul. Blackland prairies, dry hillsides and woods, roadside and railroad verges, slopes and ravines, limestone and sandstone hills; 200–500 m; Ark., Kans., Okla., Tex.
The Kansas distribution of Rosa foliolosa is limited to Cherokee and Neosho counties, bordering Missouri and Oklahoma.
Rosa foliolosa is the only white rose native to North America; a pink form is known from Wise County, Texas (W. H. Lewis 1959). Rosa foliolosa is the most distinctive and geographically limited native Rosa in eastern North America, readily recognized by its white or, rarely, pink, narrow (6–18 mm) petals, lustrous, deep green and narrow (9 mm) leaflets, short pedicels (2–8 mm), leathery, dull red hips, and mostly basal achenes.

(2018)  
 
Rosa gymnocarpa Nuttall in J. Torrey and A. Gray, Fl. N. Amer. 1: 461. 1840.
Rosa gymnocarpa Nuttall var. gymnocarpa
Wood or baldhip rose
Rosa abietorum Greene; R. helleri Greene; R. leucopsis Greene; R. piscatoria Greene
Description