Pacific ninebark (Trees & Shrubs of the Sunol Region

Pacific ninebark

Physocarpus capitatus

Summary ⁷

Physocarpus capitatus, commonly called Pacific ninebark or tall ninebark, is a species of Physocarpus native to western North America from southern Alaska east to Montana and Utah, and south to southern California.

Description ⁸

Pacific ninebark is a long-lived perennial shrub of the Rose family native to the Pacific Northwest. It grows rapidly with multiple stems achieving 2 to 4 meters in an erect to arching form with angled branches. The reddish papery bark peels off in long thin layers giving rise to the common name. Deciduous leaves that appear alternately along the stem are 3-10 cm long, 3-5 lobed and doubly toothed at the margin. They are deeply veined, shiny dark green above and lighter beneath with fine star-shaped hairs. Fall color is described as rose-brown. Small (4 mm wide), 5-petaled creamy white flowers with pink stamens form dense rounded clusters at the branch terminals. Flowers appear between late April and July. One to four hard shiny pear-shaped yellow seeds form within small fruits that are individually surrounded by dark reddish brown, bell-shaped bracts. These bracts often persist during winter. For a current distribution map, please consult the Plant Profile page for this species on the PLANTS Web site.

Adaptation and Distribution: Pacific ninebark prefers partial shade but tolerates full sun and is adapted to course, medium and fine textured slightly acidic soils. Occupying low to middle elevations in areas with annual precipitation of 50 to 200 cm, this species has low fertility requirements and low drought tolerance. Pacific ninebark is scattered to common west of the Cascades and often abundant in wet areas and on steep north slopes of the coastal mountains. Habitats include streambanks, lake margins, and swampy areas or openings in moist woods. Occasionally, Pacific ninebark is found in coastal marsh lands and meadows or at drier shrubby sites. Pacific ninebark occurs primarily west of the British Columbia Coast, Cascade, and Sierra Nevada Mountain Ranges from extreme southeast Alaska to central California. It is less prevalent east of the Cascades where its range extends along the Columbia, Snake and Clearwater Rivers into Idaho and overlaps with that of mallow ninebark (Physocarpus malvaceus).