Spiraea japonica is a plant

Plant

Plants are living organisms belonging to the kingdom Plantae. Precise definitions of the kingdom vary, but as the term is used here, plants include familiar organisms such as trees, flowers, herbs, bushes, grasses, vines, ferns, mosses, and green algae. The group is also called green plants or...

 in the family Rosaceae

Rosaceae

Rosaceae are a medium-sized family of flowering plants, including about 2830 species in 95 genera. The name is derived from the type genus Rosa. Among the largest genera are Alchemilla , Sorbus , Crataegus , Cotoneaster , and Rubus...

. Synonyms for the species name are Spiraea bumalda Burv. and Spiraea japonica var. alpina Maxim.

Description

Spiraea japonica is one of several Spiraea

Spiraea

Spiraea , is a genus of about 80-100 species of shrubs in the family Rosaceae, subfamily Spiraeoideae. They are native to the temperate Northern Hemisphere, with the greatest diversity in eastern Asia....

 shrub

Shrub

A shrub or bush is distinguished from a tree by its multiple stems and shorter height, usually under 5–6 m tall. A large number of plants may become either shrubs or trees, depending on the growing conditions they experience...

s with alternate, simple leaves

Leaf

A leaf is an organ of a vascular plant, as defined in botanical terms, and in particular in plant morphology. Foliage is a mass noun that refers to leaves as a feature of plants....

, on wiry, freely branching, erect stems. Stems are brown to reddish-brown, round in cross-section and sometimes hairy. The shrub reaches 1.2 m to almost 2 m in height and about the same in width. The deciduous

Deciduous

Deciduous means "falling off at maturity" or "tending to fall off", and is typically used in reference to trees or shrubs that lose their leaves seasonally, and to the shedding of other plant structures such as petals after flowering or fruit when ripe...

 leaves are generally an ovate shape about 2.5 cm to 7.5 cm long, have toothed margins, and alternate along the stem. Clusters of rosy-pink flowers are found at the tips of the branches. The seeds measure about 2.5 mm in length and are found in small lustrous capsules.

It is naturally variable in form and there are many varieties of it in the horticulture trade. So far, nine varieties have been described within the species.

Distribution

Spiraea japonica is a deciduous, perennial shrub native to Japan, China, and Korea. Southwest China is the center for biodiversity of the species. It is naturalized throughout much of the Northeast, Southeast, and Midwest areas of the United States

United States

The United States of America is a federal constitutional republic comprising fifty states and a federal district...

, and parts of Canada

Canada

Canada is a North American country consisting of ten provinces and three territories. Located in the northern part of the continent, it extends from the Atlantic Ocean in the east to the Pacific Ocean in the west, and northward into the Arctic Ocean...

.

Habitat

A common habitat for S. japonica in general seems to be in riparian areas, bogs, or other wetland habitats. It is 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 prefers lots of water during the growing season; however, it cannot tolerate saturated soils for extended periods of time. It prefers a rich, moist loam, but it can grow in a wide variety of soils, including those on the alkaline side.

Uses

Spiraea japonica was introduced in North America

North America

North America is a continent wholly within the Northern Hemisphere and almost wholly within the Western Hemisphere. It is also considered a northern subcontinent of the Americas...

 as an ornamental landscape plant and first cultivated in the northeastern states around 1870.

It is a common ornamental. The tall forms are grown as hedges, low screens, or foundation shrubs. The low-growing forms are used as groundcovers or in borders. It has been used as traditional medicine by native people, and extracts from the plants were found to be bioactive.

Invasiveness

Spiraea japonica has become naturalized in North America and occupies habitats similar to those of native spireas. It aggressively invades disturbed areas and forms dense stands that outcompete native species. It often spreads locally when its hardy seeds are transported along watercourses or in fill dirt.

Once established, S. japonica grows quickly and forms dense stands that outcompete much of the existing native herbs and shrubs. The seeds can last for many years in the soil, making its control and the restoration of native vegetation especially difficult. Growing populations will creep into meadows, forest openings, and other sites.

External Links

• Species Profile- Japanese Spiraea (Spiraea japonica), National Invasive Species Information Center, United States National Agricultural Library
  United States National Agricultural Library
  The United States National Agricultural Library is one of the world's largest agricultural research libraries, and serves as a National Library of the United States and as the library of the United States Department of Agriculture...
  
  . Lists general information and resources for Japanese Spiraea.