For the European and west Asian herb in the same family, see True Meadowsweet.

Spiraea ( /spaɪˈriːə/),^[2] is a genus of about 80-100 species of shrubs in the family Rosaceae. They are native to the temperate Northern Hemisphere, with the greatest diversity in eastern Asia.

Spiraea species are used as food plants by the larvae of some Lepidoptera species including Brown-tail, Emperor Moth, Grey Dagger, Hypercompe indecisa and Setaceous Hebrew Character.

The genus was formerly treated as also containing the herbaceous species now segregated into the genera Filipendula and Aruncus; recent genetic evidence has shown that Filipendula is only distantly related to Spiraea, belonging in the subfamily Rosoideae.

Description

Flower diagram of Spiraea hypericifolia.

Spiraea × arguta flowers

Spiraea plants are hardy, deciduous-leaved shrubs. The leaves are simple and usually short stalked in an alternate (i.e. spiral) arrangement. In most species, the leaves are lanceolate (narrowly oval) and about 1 to 4 inches (2.5 to 10 cm) long. The leaf margins are usually toothed, occasionally cut or lobed, and rarely smooth. Stipules are absent.

The many small flowers of Spiraea shrubs are clustered together in inflorescences, usually in dense panicles, umbrella-like corymbs, or grape-like clusters. The radial symmetry of each flower is five-fold, with the flowers usually bisexual, rarely unisexual. The flowers have five sepals and five white, pink, or reddish petals that are usually longer than the sepals. Each flower has many (15 to 60) stamens.

Uses

Horticulture

Spiraea japonica (Japanese spiraea), a commonly cultivated Spiraea species

Many species of Spiraea are used as ornamental plants in temperate climates, particularly for their showy clusters of dense flowers. Some species bloom in the spring, and others bloom mid-summer.

Medicinal uses and toxicity

Spiraea is too woody to be used as an edible plant, but has a long history of medicinal use by Native Americans as an herbal tea.^{[citation needed]}

Spiraea shrubs contain methyl salicylate (oil of wintergreen) and other salicylates throughout the plant,^{[citation needed]} compounds with similar medicinal properties to aspirin. Unlike such other salicylate-bearing plants as willow (Salix) or poplar (Populus), spiraea's content of these analgesic compounds appears to be consistent from plant to plant.^{[citation needed]} The salicylates in this plant are considered to be highly effective as an analgesic, anti-inflammatory, and fever reducer, without the side effects attributed to aspirin.^{[citation needed]} Unlike aspirin, spiraea is effective in treating stomach disorders in minute amounts.^{[citation needed]}

Certain compounds in this plant also have bacteriostatic properties,^{[citation needed]} and the tea of this plant was used by the Blackfeet Indians as an enema and vagina douche to treat infections of the bowels and vaginal area.^[3]

Many kinds of plants produce methyl salycylate, and it is also easily synthesized industrially. While useful as a flavoring or medicinal in small quantities, larger amounts (from any source) can be hazardous or fatal, as discussed in the methyl salicylate article.

Species

Spiraea douglasii (Hardhack)

Spiraea thunbergii flowers

Hybrids

Spiraea × vanhouttei, a commonly cultivated hybrid Spiraea

There are also numerous named hybrids, some occurring naturally in the wild, others bred in gardens, including several important ornamental plants:

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References

1. ^ Potter, D. et al.; Eriksson, T.; Evans, R. C.; Oh, S.; Smedmark, J. E. E.; Morgan, D. R.; Kerr, M.; Robertson, K. R. et al (2007). "Phylogeny and classification of Rosaceae". Plant Systematics and Evolution 266 (1–2): 5–43. doi:10.1007/s00606-007-0539-9.  [Referring to the subfamily by the name "Spiraeoideae"]
2. ^ Sunset Western Garden Book, 1995:606–607
3. ^ Edible and Medicinal Plants of the West, Gregory L. Tilford, ISBN 0-87842-359-1