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ninebark, Pacific nine-bark, tall ninebark

Habit Shrubs, to 45(–60) dm.
Stems

erect, sometimes suckering, angled, glabrous or finely stellate-hairy.

Leaves

stipules linear to narrowly elliptic, 4 × 0.5–2 mm;

petiole 1–2(–3) cm;

blade broadly ovate to obovate, (3–)4–8 cm, usually as wide as long, base rounded to truncate or slightly cordate, 3- or 5-lobed, margins irregularly crenate to doubly serrate, apex obtuse to acute, abaxial surface paler, glabrous or more densely stellate-hairy, adaxial glabrous or sparsely stellate-hairy.

Inflorescences

30–50-flowered, dense, hemispheric racemes, 3 cm diam., sometimes compound with some proximal pedicels becoming secondary peduncles;

bracts narrowly elliptic to spatulate, 4 × 2 mm, apex acute or erose-dentate, faces glandular.

Pedicels

1–1.5 cm, densely stellate-hairy.

Flowers

5–8 mm diam.;

hypanthium cup-shaped, 2 mm, densely stellate-hairy;

sepals pale green to white, darker in center, triangular, 2–3 mm, apex gland-tipped, surfaces densely stellate-hairy;

petals white, broadly elliptic to orbiculate, 3–4 × 3–4 mm;

stamens equal to or exceeding petals;

carpels 3–5, connate basally, mostly glabrous, sometimes hairy (on ventral suture).

Seeds

2(–5), pyriform, 2.3–2.8 mm.

Follicles

3–5, connate basally, shiny brown, ovoid, 5–7 mm (lengths slightly exceeding sepals), glabrous;

styles 2.5–3 mm.

2n

= 18.

Physocarpus capitatus

Phenology Flowering May–Jul; fruiting Jul–Aug.
Habitat Open sunny slopes on clay (higher elevations), stream and swamp banks, lake margins in moist woods (lower elevations)
Elevation 20–1300 m (100–4300 ft)
Distribution
from FNA
AK; CA; ID; OR; WA; BC
[WildflowerSearch map]
[BONAP county map]
Discussion

Physocarpus capitatus is commonly cultivated.

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

Source FNA vol. 9, p. 349.
Parent taxa Rosaceae > subfam. Amygdaloideae > tribe Neillieae > Physocarpus
Sibling taxa
P. alternans, P. intermedius, P. malvaceus, P. monogynus, P. opulifolius
Synonyms Spiraea capitata, P. opulifolius var. tomentellus
Name authority (Pursh) Kuntze: Revis. Gen. Pl. 1: 219. (1891)
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