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cluster rose, cluster wild rose, peafruit rose, swamp rose

Habit Shrubs, loosely clustered or in dense thickets.
Stems

ascending to erect, (2–)4–20(–25) dm, openly branched;

bark ± glaucous when young, dark reddish brown or dull red with age outer layer may exfoliate as thin ash gray peel, glabrous;

infrastipular prickles usually paired, erect, rarely curved, usually subulate, 2–10 × 2–4 mm, base glabrous, internodal prickles rare or absent.

Leaves

5–10(–13) cm;

stipules 8–22 × 2–5 mm, auricles flared, 2–5 mm, margins usually entire, sometimes erose or lobed, finely ciliolate to ciliate, eglandular, surfaces glabrous or sparsely pubescent, sparsely stipitate-glandular or eglandular;

petiole and rachis sometimes with pricklets, glabrous or hairy hairs to 1 mm, sometimes stipitate-glandular;

leaflets 5–7(–9), terminal: petiolule 8–12 mm, blade elliptic-ovate, (15–)20–45(–60) × 9–16(–20) mm, widest at or below middle, membranous, base cuneate to obtuse, margins 1(–2)-serrate, teeth 12–22 per side, on distal 3/4–4/5 of margin, acute, eglandular, apex acute, sometimes obtuse, abaxial surfaces pale green, usually sparsely pubescent, eglandular, adaxial green, dull, glabrous, rarely puberulent.

(2–)3.5–15(–18) cm;

leaflets 3–11(–13), margins usually serrate, rarely deeply incised or broadly crenate, terminal: petiolule (1–)5–20(–40) mm, blade elliptic, lanceolate, oblong, ovate, suborbiculate, obovate, and/or cordate, base not cuneate.

Inflorescences

corymbs, sometimes panicles or solitary flowers, 1–12-flowered.

corymbs or panicles, commonly solitary or few, 1–16(–50)-flowered.

Pedicels

erect, sometimes recurved, slender, 10–22 mm, usually glabrous, sometimes finely puberulent, eglandular, rarely stipulate-glandular;

bracts 2–3, lanceolate, 8–14 × 3–6 mm, margins entire, sometimes serrate, irregularly stipitate-glandular and/or erose, surfaces glabrous or pubescent, eglandular.

bracts present (absent in sect. Pimpinellifoliae).

Flowers

2.4–3.8 cm diam.;

hypanthium ovoid-urceolate, 3–5 × 2.5–3.5 mm, glabrous, rarely setose, eglandular, neck (0–)0.5–1 × 2 mm;

sepals spreading, ovate-lanceolate, 10–17 × 1.5–3 mm, tip 3–7(–10) × 1.5–2.5 mm, margins entire, abaxial surfaces sometimes puberulent, densely or sparsely stipitate-glandular, rarely eglandular;

petals single, pink to deep pink, 12–18 × 10–18 mm;

stamens 75;

carpels 22–35, styles exsert 1–2 mm beyond stylar orifice (1 mm diam.) of hypanthial disc (3.5 mm diam.).

hypanthium globose to depressed-globose, ovoid, oblong, or urceolate, rarely cupulate, obovoid, or hemispheric, glabrous, rarely setose, eglandular or stipitate-glandular;

carpels 3–35(–68), styles free or connate, pubescent, sometimes glabrous, stylar orifice 0.5–3(–5) mm diam., rims 0.5 mm wide, hypanthial disc flat or conic.

Hips

scarlet, globose, sometimes subglobose or ovoid, 7–15 × 7–13 mm, fleshy, glabrous, eglandular, rarely setose- or stipitate-glandular, neck (0–)1–1.5 × 1.5–3.5 mm;

sepals persistent, erect.

fleshy, rarely leathery, ± setose or not.

Achenes

basiparietal, 5–35, tan, 3–4 × 1.5–2.5 mm.

2n

= 14, 28.

Rosa pisocarpa

Rosa subg. Rosa

Distribution
from FNA
CA; OR; WA; BC
[WildflowerSearch map]
[BONAP county map]
North America; Mexico; Eurasia; n Africa [Introduced widely worldwide]
Discussion

Subspecies 2 (2 in the flora).

(Discussion copyrighted by Flora of North America; reprinted with permission.)

Species ca. 135 (31 in the flora).

Subgenus Rosa includes seven sections, all represented in the flora area, five only by introduced species.

(Discussion copyrighted by Flora of North America; reprinted with permission.)

Key
1. Inflorescences (1–)3–12-flowered; sepal abaxial surfaces usually stipitate-glandular, tips to 10 mm; infrastipular prickles (1–)2; hips usually globose, rarely subglobose, abruptly narrowed to necks 1.5–3 mm diam.; leaflets most commonly 7, terminal blade 15–35 mm.
subsp. pisocarpa
1. Inflorescences 1–3(–10+)-flowered; sepal abaxial surfaces usually eglandular, rarely stipitate-glandular, tips to 7 mm; infrastipular prickles 0–1(–2); hips subglobose to ovoid, gradually to abruptly narrowed to necks 2.5–3.5 mm diam.; leaflets most commonly 5, terminal blade 20–45(–60) mm.
subsp. ahartii
Source FNA vol. 9, p. 109. FNA vol. 9, p. 82.
Parent taxa Rosaceae > subfam. Rosoideae > tribe Roseae > Rosa > subg. Rosa > sect. Rosa Rosaceae > subfam. Rosoideae > tribe Roseae > Rosa
Sibling taxa
R. acicularis, R. arkansana, R. blanda, R. bracteata, R. bridgesii, R. californica, R. canina, R. carolina, R. cinnamomea, R. foliolosa, R. gallica, R. glauca, R. gymnocarpa, R. laevigata, R. lucieae, R. minutifolia, R. mollis, R. multiflora, R. nitida, R. nutkana, R. palustris, R. pinetorum, R. rubiginosa, R. rugosa, R. setigera, R. sherardii, R. spinosissima, R. spithamea, R. stellata, R. tomentosa, R. virginiana, R. woodsii
Subordinate taxa
R. pisocarpa subsp. ahartii, R. pisocarpa subsp. pisocarpa
Name authority A. Gray: Proc. Amer. Acad. Arts 8: 382. (1872) unknown
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