About Spiraea japonica L.fil.
Spiraea japonica L.fil. is a species of Spiraea shrub. It has alternate, simple leaves that grow on wiry, freely branching, erect stems. Stems are brown to reddish-brown, round in cross-section, and sometimes hairy. Mature shrubs reach 1.2 meters to nearly 2 meters in height, with a roughly equal spread. The deciduous leaves are generally ovate in shape, 2.5 to 7.5 centimeters long, have toothed margins, and grow alternately along stems. Clusters of rosy-pink flowers form at the tips of branches. Its seeds measure around 2.5 millimeters in length, and are held inside small lustrous capsules. This species is naturally variable in form, and many varieties are available through the horticulture trade. To date, nine varieties have been formally described within this species. Spiraea japonica is a deciduous, perennial shrub native to Japan, China, and Korea. Southwest China is the center of biodiversity for this species. It has become naturalized across most of the Northeast, Southeast, and Midwest regions of the United States, as well as in parts of Canada. Common habitats for S. japonica include riparian areas, bogs, and other wetland habitats. It can be found growing along streams, rivers, forest edges, roadsides, successional fields, and power line right-of-ways. It prefers full sun, but can tolerate partial shade. It requires ample water during the growing season, but cannot tolerate extended periods of saturated soil. It grows best in rich, moist loam, but can thrive in a wide variety of soils, including alkaline soils. Spiraea japonica was introduced to North America as an ornamental landscape plant, and was first cultivated in the northeastern United States around 1870. Numerous cultivars have been selected for garden use. Tall forms may be grown as hedges, low screens, or foundation shrubs. Low-growing forms can be used as groundcover or in garden borders. Some cultivars of S. japonica have gained the Royal Horticultural Society's Award of Garden Merit in the UK. S. japonica has been used as a traditional medicine by native peoples, and plant extracts from the species have been found to be bioactive.
