ninebark, any plant of the genus Physocarpus of the family Rosaceae ( rose family). Ninebarks are North American (one is Asian) deciduous, hardy, spring-blooming shrubs, with thin bark which peels off in many layers. The most common American species is P. opulifolius, found along rocky streams E of the Rockies. Ninebarks are similar to the closely related spiraeas and are also cultivated as ornamentals. Ninebarks are classified in the division Magnoliophyta , class Magnoliopsida, order Rosales, family Rosaceae.
The Columbia Electronic Encyclopedia, 6th ed. Copyright © 2012, Columbia University Press. All rights reserved.
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