A shrub 3 to 5 ft high, with spreading underground roots, ultimately forming a thicket of erect angled stems which when young are covered with brownish felt. Leaves ovate, 11⁄2 to 3 in. long, 3⁄4 to 11⁄2 in. wide, coarsely and irregularly toothed almost to the base, dark green and nearly glabrous above, covered with a close, yellowish grey felt beneath. Flowers purplish rose, densely produced in erect, terminal, branching panicles 4 to 7 in. long, 11⁄2 to 21⁄2 in. wide during late summer.
Native of the eastern United States; introduced, according to Aiton, in 1736. It is allied to the western S. douglasii, and is often confused with it; it is, however, distinguished by the thicket, browner (or yellowish) felt beneath the leaves, which are toothed much nearer the base; by flowering some weeks later, and by the ovaries being woolly (glabrous in S. douglasii).
f. alba (Weston) Rehd. – A pretty white-flowered form.
The cultivation of these handsome spiraeas is the same as for S. douglasii.