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Atlantic nine-bark, common nine-bark, physocarpe à feuilles d'obier

few-flower ninebark, mallow nine-bark, mallow-leaf nine-bark

Habit Shrubs, to 30 dm. Shrubs, 20 dm.
Stems

spreading to ascending, ± glabrous.

spreading, brown becoming grayish black, glabrous or finely stellate-hairy.

Leaves

stipules narrowly ovate, 6–10 × 1.5–2.5 mm, apex acute;

petiole 1–3 cm;

blade ovate to obovate, 6–8.5(–10) × 4–7(–10) cm, usually longer than wide, base broadly cuneate to truncate, 3(–5)-lobed, margins irregularly serrate, apex obtuse to rounded, surfaces mostly glabrous, sometimes sparsely hairy abaxially.

stipules oblong to elliptic or obovate, 6 × 2.5 mm, base broad, apex rounded and erose to apiculate or acute;

petiole 1–2.5(–3) cm;

blade broadly ovate to orbiculate, 2–6 × 2.5–6 cm, sometimes wider than long, base truncate to slightly cordate, 3- or 5-lobed, clefts between lobes may be shallow to deep, margins doubly crenate to doubly serrate, apex rounded, obtuse, or acute, surfaces glabrous or sparsely stellate-hairy (more so on abaxial veins).

Inflorescences

30–50-flowered, open, hemispheric racemes, 5 cm diam.;

bracts elliptic to spatulate or rhombic, 5 × 2.5 mm, apex acute to 3-fid or coarsely erose, faces glandular.

15–20-flowered, fairly dense, hemispheric racemes, 2.5–4 cm diam.;

bracts narrowly obovate to spatulate, 4.5 mm, apex erose or acute.

Pedicels

1–2 cm, usually stellate-hairy.

8–15 mm, densely stellate-hairy.

Flowers

7–10 mm diam.;

hypanthium cup-shaped, 1.5–2 mm, glabrous or sparsely stellate-hairy;

sepals pale green to white, darker in center, triangular, 1.5–2.5 mm, apex mucronate, gland-tipped, surfaces usually stellate-hairy;

petals white to pale pink, broadly elliptic to orbiculate, 4–5 × 4–5 mm;

stamens equal to or exceeding petals, anthers purplish;

carpels 3–5, connate basally, sparsely stellate-hairy, glabrescent.

5–8 mm diam.;

hypanthium campanulate, 1.5–2 mm, densely stellate-hairy;

sepals triangular to ovate, 2–3 mm, apex gland-tipped, surfaces densely stellate-hairy;

petals white, broadly elliptic to obovate or orbiculate, 4.5 × 4.5 mm;

stamens ca. 30, equal to or slightly exceeding petals;

carpels 2(3), connate at least 1/2 their lengths, densely stellate-hairy.

Seeds

2(–5), pyriform, 2 mm.

1 or 2, pyriform, 1.5 mm.

Follicles

3–5, connate basally, bright red to brownish red, ovoid, 5–10 mm (lengths ca. 2 times sepals), sparsely stellate-hairy, ± glabrescent;

styles 4 mm.

2(3), ovoid, flattened, 2.5 mm (lengths not exceeding sepals), keeled apically, densely stellate-hairy, hairs white;

styles 2.5–3 mm.

2n

= 18.

Physocarpus opulifolius

Physocarpus malvaceus

Phenology Flowering May–Jun; fruiting Jul–Sep. Flowering May–Jul; fruiting Aug.
Habitat Rocky stream banks, lake shores, moist woods, swampy ground Rocky canyon slopes and cliffs, open grassy slopes, dry open forests among Pinus, Juniperus, Pseudotsuga, Picea, and Populus
Elevation 0–1300 m (0–4300 ft) 500–2800 m (1600–9200 ft)
Distribution
from FNA
AL; AZ; CT; DC; DE; FL; GA; IA; IL; IN; KS; KY; MA; MD; ME; MI; MN; MS; NC; ND; NE; NH; NJ; NY; OH; OK; PA; RI; SC; SD; TN; VA; VT; WI; WV; NB; NS; ON; QC [Introduced in Europe]
[WildflowerSearch map]
[BONAP county map]
from FNA
CO; ID; MT; NV; OR; UT; WA; WY; AB; BC
[WildflowerSearch map]
[BONAP county map]
Discussion

Physocarpus opulifolius is the most widespread species in the wild and is commonly cultivated in North America and Europe; it occasionally escapes from cultivation and has become established in parts of Europe.

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

Physocarpus malvaceus deserves to be more widely cultivated.

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

Source FNA vol. 9, p. 348. FNA vol. 9, p. 349.
Parent taxa Rosaceae > subfam. Amygdaloideae > tribe Neillieae > Physocarpus Rosaceae > subfam. Amygdaloideae > tribe Neillieae > Physocarpus
Sibling taxa
P. alternans, P. capitatus, P. intermedius, P. malvaceus, P. monogynus
P. alternans, P. capitatus, P. intermedius, P. monogynus, P. opulifolius
Synonyms Spiraea opulifolia, Opulaster alabamensis, O. australis, O. opulifolius, O. stellatus Neillia malvacea, Opulaster pauciflorus, P. pauciflorus
Name authority (Linnaeus) Maximowicz: Trudy Imp. S.-Petersburgsk. Bot. Sada 6: 220. (1879) (Greene) Kuntze: Revis. Gen. Pl. 1: 219. (1891)
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