Shrubs of Wisconsin

Spiraea alba (L.) Moench.
Family: Rosaceae
shrub branch leaves inflorescence mature fruit twig


Spiraea alba is an erect shrub usually one meter or less tall. The growth form may be quite narrow if undisturbed or much-branched and bushy if the tops are broken or browsed as is frequently the case in my experience. Leaves are simple, alternate, 5-7 cm long, 1-2 cm wide and regularly toothed (margins may be entire toward the base of some leaves). Bark of the twigs is brown or yellowish brown. Each flower has 5 white petals, strongly narrowed at the base, and 5 green, broadly triangular sepals. Flowers are aggregated into conspicuous terminal elongate, pyramidal inflorescences. The fruits are dry, brown follicles opening broadly at the tip when ripe and long-persistent on the stems.

Spiraea alba is found throughout Wisconsin, most commonly on sunny sites, in moist to wet soil. It may also do well on heavier soils in more upland habitats on heavily disturbed sites. In either habitat it may persist for many years as a canopy grows up around it, in which case the increasingly shaded plants may be smaller and often do not flower.


known Wisconsin distribution


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