246 NORTH AMERICAN FLORA [VoLUME 22 
A. Inflorescence simple. 
Flowers in axillary umbels. 1. S. pruntfolia. 
Flowers in terminal racemes or corymbs. 
Flowers racemose; leaves entire. 2. S. Hartwegiana. 
Flowers corymbose ; leaves toothed. 3, S. ulmifolia. 
B. Inflorescence compound; flowers paniculate. 
I. Panicle flat-topped. 
Sepals reflexed. 
Carpels hairy ; corolla white. 4. S. Slevent. 
Carpels glabrous ; corolla rose-colored. 17. S: subvillosa. 
Sepals erect or spreading. 
Petals pink or rose-colored. 
Young twigs, branches of the inflorescence, petioles and veins of 
the leaves beneath finely puberulent. 5. S. splendens. 
Whole plant glabrous, except a few cilia on the leaves and bracts. 
Leaves rounded-oval to elliptic, crenate above, entire at the 
base; sepals rounded at the apex. 6. S. densifiora. 
Leaves elliptic-oblong, sharply serrate; sepals acutish. 7. S. Helleri. 
Petals white, seldom tinged with rose; corymb larger. 
Plant perfectly glabrous. 8. S. lucida. 
Plant more or less hairy. 
Hypanthium abruptly contracted below; leaves slightly if at 
all glaucous, oval to oblong. . 5. corynibosa. 
Hypanthium turbinate, gradually tapering below ; leaves very 
glaucous beneath, very acute. 
Leaf-blades oblanceolate or obovate, entire or toothed to- 
wards the apex. 10. S. virginiana. 
Leaf-blades lanceolate or ovate, sharply serrate, except at . 
the base. 11. S. japonica. 
II, Panicle elongate, conic, ovoid, or lanceolate. 
Sepals merely spreading ; disk obsolete. 
Inflorescence glabrous; leaf-blades broadly oblanceolate to obovate. 12. S. latifolia. 
Inflorescence pubescent. 
Leaf-blades narrowly oblanceolate, broadest above the middle; 
petals white. 13. S. alba. 
Leaf-blades lance-elliptic, broadest about the middle; petals 
pinkish. 14, S. salicifolia. 
Sepals soon reflexed ; disk usually rather conspicuous. 
Leaves not tomentose beneath. 
Inflorescence short and rather open, oblong, ovoid or obovoid. 
Young branches and leaves glabrous; inflorescence small ; 
petals pink. 15. S. roseola. 
Young branches more or less pubescent ; inflorescence usually 
large. 
Leaves glabrous or nearly so, except the margin; petals 
white. 16. S. pyramidaia. 
Leaves finely pubescent beneath ; petals pink. 17. S. subvillosa. 
Inflorescence long, dense, usually cylindric; petals rose or pink. 18. S. Menziesit. 
- Leaves tomentose beneath. 
Petals white ; inflorescence short, obovoid. 19. S. tomeniulosa. 
Petals rose or purplish ; inflorescence cylindric. 
Follicles glabrous. 
Leaves widest at or above the middle, coarsely toothed 
above, entire at the base. 20. S. Douglasit. 
Leaves lanceolate, broadest below the middle, finely serrate 
throughout. 21. S. subcanescens. 
Follicles arachnoid-hairy ; leaf-blades ovate or oval, acute at 
both ends. 22. S. lomentosa. 
1. Spiraea prunifolia Sieb. & Zucc. Fl. Jap.1: 131. 1835. 
Ashrub, 1-3 m. high, upright with slender branches ; bark of these brown, at first finely 
pubescent; leaves short-petioled ; blades 2-5 cm. long, ovate or elliptic, serrulate, softly 
pubescent beneath, glabrous or nearly so above ; flowers in 3-6-flowered umbels ; pedicels 
1-3 cm. long; sepals ovate, obtuse, 1.5 mm. long; petals pure white, rounded-obovate, 4- 
5 mm. long, exceeding the stamens; follicles glabrous. A cultivated form has double 
flowers on comparatively long pedicels and more shining leaves. 
TYPE LOCALITY: Cultivated in Japanese gardens, probably from Korea or northern China. 
DISTRIBUTION : Extensively cultivated and occasionally escaped in the New England States. 
ILLUSTRATIONS: Sieb. & Zucc. Fl. Jap. pi. 70; Otto, Gartenzeit. 1847: pl. 7; Fl. Serres 2: pi. 
153, 154; C. K. Schneid. Handb. Laubh. 1: f. 288. 
.2, Spiraea Hartwegiana Rydberg. 
Spiraea parvifolia Benth. Pl. Hartw. 36. 1840. Not S. parvifolia Raf. 1838. 
A small shrub, 9-12 dm. high; bark of the twigs chestnut-brown, glabrous, shining ; 
buds glabrous; leaf-blades oblanceolate or linear-cuneate, rather crowded, 7-15 mm. long, 2-3 
