248 NORTH AMERICAN FLORA [VorumE 22 
1 mm. long, surpassed by the slender filaments ; follicles shining, oblanceolate, their bodies 
about 2.5 mm. and beaks 1 mm. long ; seeds linear-lanceolate, nearly 2 mm. long. 
TYPE LOCALITY : California. 
DISTRIBUTION: In the mountains of California and Oregon. 
6. Spiraea densiflora Nutt.; T. & G. Fl. N. Am. 1: 414. 1840. 
A low shrub, 2-6 dm. high, with ascending branches; bark of the twigs dark reddish- 
brown, glabrous, the outer layers exfoliating sooner or later; that of the older stems often 
dark purplish-brown ; leaves with very short petioles; blades oval or elliptic, rounded at 
each end, glabrous or essentially so, bright-green above, somewhat paler beneath, crenate 
or serrate above the middle, entire at the base, 1.5-3 cm. long; inflorescence small, flat- 
topped or rounded, 2-4 cm. high and broad, its branches glabrous; hypanthium glabrous, 
hemispheric, slightly more than 1 mm. deep; sepals ovate, obtuse, erect or merely spread- 
ing; petals rose-colored, nearly 1.5 mm. long, obovate, surpassed by the slender filaments ; 
follicles glabrous and shining, oblanceolate, their, bodies nearly 3 mm. and beaks 1 mm. 
long ; seeds linear-lanceolate, nearly 2 mm. long. 
TYPE LOCALITY: Not given, but Nuttall’s specimens were collected in the Blue Mountains of 
Oregon. 
DISTRIBUTION : In the mountains from British Columbia to Oregon, Wyoming, and Montana. 
7. Spiraea Helleri Rydberg, sp. nov. 
A low shrub, less than 1 m. high; bark of twigs glabrous, reddish-brown, becoming very 
dark and exfoliating the next year ; petioles about 2mm. long; leaf-blades rather dark-green, 
glabrous, elliptic, acute or obtuse, 2-4 cm. long, sharply serrate, except at the very base; 
inflorescence flat-topped or rounded, about 3 cm. broad and high, its branches glabrous; 
hypanthium glabrous, hemispheric, about 1 mm. deep; sepals ovate, acute, erect or spread- 
ing, about 1 mm. long; petals rose-colored, oval, 1.5 mm. long. 
Type collected near Summit Station (Donner Pass), Nevada County, California, in 1903, A. A. 
ffeller 7022 (herb. N. Y. Bot. Gard.) 
DISTRIBUTION : On damp hillsides, Sierra Nevada, in the vicinity of the type locality. 
8. Spiraea lucida Dougl.; Hook. Fl. Bor. Am. 1: 172, asa synonym. 
1832. — Greene, Pittonia 2: 221. 1892. 
Spiraea betultfolia Hook. Fl. Bor. Am.1: 172. 1832. Not S. be/ulifolia Pall. 1784. 
Spiraea corymbosa lucida Zabel, Handb. Laubh. Deuts. Dendr. Ges. 157. 1903. 
A low shrub, with creeping rootstock ; stems and branches erect, often dying down annu- 
ally to near the base, 3-10 dm. high; bark of the twigs glabrous, rather light-brown, the 
outer layers sooner or later peeling off and then becoming darker ; petioles 4-8 mm. long; 
blades of the lower leaves obovate, of the upper oval, often acutish, 2-6 cm. long, thin, 
glabrous throughout, more or less shining above, paler beneath, coarsely serrate or incised ; 
inflorescence flat-topped, 3-10 cm. broad; hypanthium hemispheric, glabrous, 1.5 mm. 
deep, light-green ; sepals triangular, acute, about 1 mm. long, erect or merely spreading ; 
petals white, orbicular, about 2 mm. long; filaments slender, about twice as long as the 
petals; follicles glabrous, shining, oblanceolate, about 3.5 mm. long, their beaks 1 mm. 
long ; seeds linear-lanceolate, attenuate at each end, 2.5-3 mm. long. 
TYPE LOCALITY : Valleys of the Rocky Mountains. 
DISTRIBUTION: In the mountains, from British Columbia to Oregon, Wyoming, and Sas- 
katchewan. 
9. Spiraea corymbosa Raf. Préc. Découv. 36. 1814. 
Spiraca betulifolia Pursh, Fl. Am. Sept. 342. 1814, Not S. betulifolia Pallas, 1784. 
Spiraea sororia Penny ; G. Don, in Loud. Hort. Brit. ed. 2. 600. 1832. 
Spiraea ostryfolia Rat. ‘New FI. 3: 69. 1838. 
Spiraea repens Raf. New F1.3: 70. 1838. 
Sptraea betulifolia corymbosa Maxim.; C. K. Schneid. Handb, Laubh. 1: 479. 1905. 
A shrub, 3-10 dm. high ; stems erect, simple or slightly branched; bark of the twigs 
chestnut-brown or reddish, usually with scattered hairs, sometimes quite pubescent or gla- 
brate, sooner or later exfoliating ; petioles 3-8 mm. long; leaf-blades thin, oval, elliptic or 
