Physocarpus malvaceus
mallow ninebark, mallow-leaf ninebark
WTU specimens
Other herbaria

Distribution: East of the Cascades, British Columbia to Oregon, east to Alberta and Montana, and south to Utah and Wyoming

Habitat: Canyons and hillsides, grasslands, ponderosa pine and Douglas fir forests

Flowers: June - July

Origin: Native

Conservation Status: Not of concern

Description:
General:

Spreading to erect shrub 0.5-2 m. tall, the branches angled, usually glabrous.

Leaves:

Leaves alternate, petiolate, the blades ovate to cordate, 3-5 lobed, the lobes bi-serrate, 4-7 cm. long and broad, dark green and glabrous above and paler below, with stellate hairs.

Flowers:

Flowers rather numerous in terminal clusters; calyx hemispheric, with stellate hairs, the 5 lobes ovate-lanceolate, 3 mm. long, somewhat reflexed; petals 5, white, sub-orbicular, 4 mm. long, spreading; stamens about 30, equaling the petals; pistils 2, attached to each other at least half way, strongly stellate-haired.

Fruits:

Fruit a glabrous follicle, 7-11 mm. long, swollen.

Accepted Name:
Physocarpus malvaceus (Greene) Kuntze
Publication: Revisio Generum Plantarum 1: 219. 1891.

Synonyms & Misapplications:
Neillia malvacea Greene
Neillia monogyna var. malvacea M.E. Jones
Neillia torreyi Hook. f.
Opulaster cordatus Rydb.
Opulaster pauciflorus (Torr. & A. Gray) A. Heller
Opulaster pubescens Rydb.
Physocarpus pauciflorus (Torr. & A. Gray) Piper
Spiraea opulifolia var. pauciflora T. & G.
Spiraea pauciflora Nutt.
Additional Resources:

PNW Herbaria: Specimen records of Physocarpus malvaceus in the Consortium of Pacific Northwest Herbaria database.

WA Flora Checklist: Physocarpus malvaceus checklist entry.

E-Flora BC: Physocarpus malvaceus atlas page.

CalPhotos: Physocarpus malvaceus photos.

USDA Plants: Physocarpus malvaceus information.

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