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

coast ground rose, dwarf rose, ground rose, Sonoma rose

Habit Shrubs, loosely clustered or in dense thickets. Subshrubs, forming open colonies.
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.

erect, 1–5(–10) dm, openly branched;

bark dark reddish brown, glabrous;

infrastipular prickles paired, erect to slightly curved, largest sometimes ± flattened, subulate, 2–8(–12) × 2–5 mm, base glabrous, internodal prickles absent or sparse to dense, mixed with aciculi, aciculi sometimes absent, stipitate-glandular or eglandular.

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.

3–10 cm;

stipules 6–15 × 1.5–2.5(–3.5) mm, auricles flared to ± erect, 1.5–6 mm, margins entire, stipitate-glandular, surfaces glabrous, eglandular;

petiole and rachis with pricklets, usually glabrous, rarely finely hairy, stipitate-glandular;

leaflets 5–7(–9), terminal: petiolule 3–13 mm, blade ovate-elliptic, sometimes obovate-elliptic, 10–30 × 8–20 mm, membranous to ± leathery, base obtuse, margins ± 2-serrate, teeth 8–20 per side, acute to obtuse, gland-tipped, apex obtuse to ± truncate, abaxial surfaces pale green to green, glabrous, sometimes sparsely hairy, sessile-glandular or eglandular, adaxial green, dull, rarely sparsely hairy.

Inflorescences

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

corymbs, 1–10-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.

erect, slender to stout, 2–15 mm, glabrous, rarely finely pubescent, stipitate-glandular, sometimes setose-glandular;

bracts 1 or 2, lanceolate, 2–15 × 1.5–5 mm, margins entire, stipitate-glandular, surfaces glabrous, 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.).

2.5–3.8 cm diam.;

hypanthium ± ovoid, 3–6 × 2.5–5 mm, glabrous, sparsely to densely stipitate- to setose-glandular, rarely eglandular, neck 0.5–1 × 2.5–4 mm;

sepals spreading, ovate-lanceolate, 8–15 × 2.5–3.5 mm, tip 0–4 × 1.3 mm, margins entire, abaxial surfaces glabrous, stipitate-glandular;

petals single, deep pink, 12–23 × 15 mm;

carpels 15–30, styles exsert 1 mm beyond stylar orifice (2 mm diam.) of hypanthial disc (3.5 mm diam.).

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.

scarlet, ± depressed-subglobose, 7–15 × 7–15 mm, fleshy, glabrous, sparsely to densely stipitate- to setose-glandular, rarely eglandular, neck 0.5–2 × 2–5 mm;

sepals persistent, erect.

Achenes

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

basiparietal, 4–17, cream to pale brown, 3.5–5 × 2.5–3.5 mm.

2n

= 14, 28.

= 14.

Rosa pisocarpa

Rosa spithamea

Phenology Flowering May–Aug.
Habitat Edges and understory of chaparral and mixed forests, post-burn openings
Elevation 200–2000 m (700–6600 ft)
Distribution
from FNA
CA; OR; WA; BC
[WildflowerSearch map]
[BONAP county map]
from FNA
CA; OR
[WildflowerSearch map]
[BONAP county map]
Discussion

Subspecies 2 (2 in the flora).

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

The combination of miniature size and stipitate- to setose-glandular hips makes Rosa spithamea one of the more easily and reliably identified species in the genus, although the density of hypanthial glands can vary. The species occurs from Douglas County, Oregon, to San Luis Obispo County, California. Rosa spithamea is fire-adapted and blooms profusely only after fires or equivalent disturbances; at other times, it persists in the understory in a vegetative state.

E. W. Erlanson (1934) referred to Rosa spithamea as tetraploid (2n = 28); twice in her key to R. spithamea she questioned that count.

(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. 118.
Parent taxa Rosaceae > subfam. Rosoideae > tribe Roseae > Rosa > subg. Rosa > sect. Rosa Rosaceae > subfam. Rosoideae > tribe Roseae > Rosa > subg. Rosa > sect. 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
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. pisocarpa, R. rubiginosa, R. rugosa, R. setigera, R. sherardii, R. spinosissima, R. stellata, R. tomentosa, R. virginiana, R. woodsii
Subordinate taxa
R. pisocarpa subsp. ahartii, R. pisocarpa subsp. pisocarpa
Synonyms R. granulata, R. sonomensis, R. spithamea var. sonomensis
Name authority A. Gray: Proc. Amer. Acad. Arts 8: 382. (1872) S. Watson: in W. H. Brewer et al., Bot. California 2: 444. (1880)
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