Northern Ontario Plant Database
Physocarpus opulifolius (L.) Raf. 1838, non (L.) Maxim. 1879
En: ninebark, eastern ninebark, common ninebark, smooth ninebark
Rosaceae (Rose Family)
General: A deciduous, many-branched shrub, 1-3 m tall. Young branches are smooth (glabrous) to slightly hair and somewhat angled; older branches have grayish-brown, papery bark that shreds off in long, thin layers.
Nomenclature: The name Physocarpus opulifolius (L.) Maxim. has been conserved over the earlier name, Physocarpus opulifolius Raf., which is now a rejected name (nom. rej.).
Leaves: Alternate, simple, palmately 3-lobed, and petiolate. Leaves have a broad, rounded to slightly cordate base, the three lobes are ovate to triangular, with blunt to acute tips, and crenate to coarsely toothed margins; young leaves develop lobes as they mature. Leaves are 3-7 cm long and almost as wide, dark green and paler beneath, and glabrous to slightly hairy; petioles are about 1-2 cm long.
Flowers: Showy, less than 1 cm across, with 5 white petals and a 5-lobed, green calyx; with numerous flowers arranged in rounded clusters (umbel-like corymbs). The flower stalks (pedicels) are minutely hairy and lengthen in fruit. Each flower has 30-40 exserted stamens; the 1-5 carpels have superior ovaries. Flowers bloom in early summer.
Fruit: A pendant cluster of smooth, dry fruits (follicles), somewhat inflated, borne on long, smooth to minutely hairy pedicels. Young fruit are green to yellowish-brown, but turn reddish at maturity, in mid August and September. The persistent follicles each contain 3-4 shiny, light brown seeds.
Habitat and Range: Rocky, sandy, or gravelly soils, in thickets, and often on gravel bars, shores, and streambanks. Ninebark is an eastern north-temperate to boreal species that occurs throughout eastern North America; it is common in northeastern Ontario, but is lacking west of 90° W (Soper & Heimburger 1982).
Similar Species: The flowers and inflorescences of ninebark are similar to those of hawthorn (Crataegus spp.), but hawthorn stems have large thorns and fleshy red-orange fruit. Also, the leaves of ninebark resemble those of highbush cranberry (Viburnum opulus var. americana), but the latter can be distinguished by its opposite leaves and fleshy red fruit.Back to species list