SPIRAEA 129 



A genus of about 60 species, natives of the north temperate zone ; four 

 occur in the eastern and two in the western part of North America; two 

 are native to Minnesota. Many of the cultivated Spiraeas are introduced 

 species, while many others are of garden origin. 



Key to the Species 



1. Flowers white, in numerous, small umbels or 



corymbs, on the upper side of arched branch- 

 es ; cultivated shrubs 



a. Corymbs terminating short, leafy shoots; 



leaves lobed S. Van Houttci 



b. Umbels sessile, subtended by a few small 



leaves; leaves not lobed S. arguta 



2. Flowers white or pink, in panicles or terminal 



corymbs, branches not arched ; cultivated and 

 native shrubs 



a. Flowers pink to rose-color, in compound 



corymbs, cultivated S. Bumalda 



b. Flowers in dense terminal panicles, white or 



rose-color ; native 



( 1 ) Leaves smooth, scarcely paler beneath S. salicifolia 



(2) Leaves green above, densely tomentose 



and white or tawny beneath S. tomcntosa 



Spiraea Van Houttei Z a b e 1 1884 Bridal Wreath 



A shrub 1-2 meters (3-6 ft.) high with arching branches, bark on 

 young branches smooth, yellowish brown, on older parts gray, and some- 

 what shreddy; leaves rhombic ovate, cut-serrate or obscurely lobed, nar- 

 rowed at the base, dark green above, pale bluish green beneath, 1.5-4 cm. 

 long; flowers in numerous many-flowered umbels, white, 5-7 mm. broad, 

 sepals upright or spreading in fruit, petals twice as long as the stamens. 



Very extensively cultivated as an ornamental shrub. A very hand- 

 some early flowering spiraea, of garden origin, a hybrid between S. 

 cantoniensis and S. triloba. 



Flowers in May and June; quite hardy and endures the Minnesota 

 winter climate without injury. 



