Spiraea japonica

Taxobox
name = Japanese spiraea

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image_width = 250px
image_caption = Inflorescence
regnum = Plantae
divisio = Magnoliophyta
classis = Magnoliopsida
ordo = Rosales
familia = Rosaceae
subfamilia = Spiraeoideae
genus = "Spiraea"
species = "S. japonica"
binomial = "Spiraea japonica"

"Spiraea japonica" (Japanese spiraea) is a plant in the rose family, Rosaceae. Synonyms for the species name are "Spiraea bumalda" Burv. and "Spiraea japonica" var. "alpina" Maxim.

Description

"Spiraea japonica" is one of several Spiraea shrubs with alternate, simple leaves, 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 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 (flowers are white to rosy-pink for natural populations native to Asia). The seeds measure about 2.5 mm in length and are found in small lustrous capsules (Remaley, 1998).

"Spiraea japonica" is naturally variable in form and there are many varieties of it in the horticulture trade. Nine varieties have been described within the species so far.

Distribution

"Spiraea japonica" is a deciduous, perennial shrub native to Japan, China, and Korea. Southwest China is the center for biodiversity of the species (Zhang et al. 2002).

Habitat

A common habitat for this genus in general seems to be in riparian areas, bogs, or other wetland habitats (Ogle 1991). According to Scheper (2000), "Spiraea japonica" prefers full sun but can tolerate partial shade. It prefers lots of water during the growing season but cannot tolerate saturated soils for extended periods of time. "S. japonica" will grow in a wide variety of soils, including those on the alkaline side, but it prefers a rich, moist loam.

Uses

It has been introduced to the United States as an ornamental and is grown in the horticulture trade.

The plant has been used as traditional medicine by native people, and extracts from the plants were found to be bioactive (Xiaojiang Hao et al. 2003).

Invasiveness

Japanese spirea have become naturalized and occupy habitats similar to those of native spireas (Ogle 1991). It aggressively invades disturbed areas and forms dense stands that outcompete native species (Ramaley 1998). "Spiraea japonica" can be found growing along streams, rivers, forest edges, roadsides, power line rights-of-way and successional fields where it has been introduced into the Eastern United States. It often spreads locally when its hardy seeds are transported along watercourses and 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 (Remaley, 1998) [ [http://www.issg.org/database/species/ecology.asp?si=622&fr=1&sts=sss Global Invasive Species Database] ] .

References