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

Photo is of parent taxon

Ahart rose, Ahart's cluster rose, Ahart's rose

Habit Shrubs, loosely clustered or in dense thickets. Plants rarely forming 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.

usually solitary or loosely clustered, (2–)4–14(–18) dm;

infrastipular prickles 0 or 1(or 2), 2–5 mm.

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.

(5–)6–11(–13) cm;

leaflets 5–7, most commonly 5, terminal blade 20–45(–60) mm.

Inflorescences

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

1–3(–10+)-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.

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.).

sepal tip to 7 mm, abaxial surfaces usually eglandular, rarely stipitate-glandular;

carpels 32–34.

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.

subglobose to ovoid, 8–13 mm diam., gradually to abruptly narrowed to neck 2.5–3.5 mm diam.

Achenes

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

5–20.

2n

= 14, 28.

= 28.

Rosa pisocarpa

Rosa pisocarpa subsp. ahartii

Phenology Flowering Jun–Aug.
Habitat Streamsides, meadow margins, roadsides in woodlands, seasonally moist areas in openings of midmontane forests
Elevation 100–1700 m (300–5600 ft)
Distribution
from FNA
CA; OR; WA; BC
[WildflowerSearch map]
[BONAP county map]
from FNA
CA; OR
[BONAP county map]
Discussion

Subspecies 2 (2 in the flora).

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

Subspecies ahartii comprises populations from the northern Sierra Nevada and southern Cascade Range (B. Ertter and W. H. Lewis 2008). Stems tend to have relatively few (or no) prickles, relatively large ovate leaves, and relatively few flowers.

(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. 110.
Parent taxa Rosaceae > subfam. Rosoideae > tribe Roseae > Rosa > subg. Rosa > sect. Rosa Rosaceae > subfam. Rosoideae > tribe Roseae > Rosa > subg. Rosa > sect. Rosa > Rosa pisocarpa
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
R. pisocarpa subsp. pisocarpa
Subordinate taxa
R. pisocarpa subsp. ahartii, R. pisocarpa subsp. pisocarpa
Name authority A. Gray: Proc. Amer. Acad. Arts 8: 382. (1872) Ertter & W. H. Lewis: Madroño 55: 171, fig. 1. (2008)
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