Spiraea thunbergii Blume

A shrub 3 to 5 ft high, often more in diameter, of very twiggy, bushy habit; branchlets slender, angled, downy. Leaves linear-lanceolate, 1 to 11⁄2 in. long, 1⁄8 to 1⁄4 in. wide, taper-pointed, the margins set with a few incurved teeth, smooth and pale green on both sides. Flowers pure white, 1⁄4 in. across, produced on the leafless, wiry twigs during March and April in clusters of two to five, each flower on a glabrous, slender stalk, 1⁄4 to 1⁄3 in. long. Calyx shallow, smooth.

Native of China; but first introduced from Japan, of which country, however, it is not native. This is the earliest of all the spiraeas to flower in the open, and in ordinary seasons is at its best by the middle of April. The fascicles of blossom spring directly from the shoots made the previous summer, and if the season has been sufficiently sunny and hot to have thoroughly ripened the wood, the plants will be almost hidden by the profusion of flowers. The habit of the plant is graceful owing to the arching form of the slender branches, and altogether there are few more attractive shrubs in bloom in early April. The leaves are slow to fall in autumn and sometimes remain on the bush throughout the winter.