'Spiraea opulifolia' definitions:

Definition of 'Spiraea opulifolia'

From: GCIDE

Nine-bark \Nine"-bark`\, n. (Bot.) A white-flowered rosaceous shrub (Neillia opulifolia, or Spiraea opulifolia), common in the Northern United States. The bark separates into many thin layers, whence the name. [1913 Webster]