Parr 3, 1908] ROSACEAE 245 
4-5 mm. wide, stellate; sepals ovate, 4-5 mm. long, stellate on both sides, acute or some- 
times obtuse; petals white, orbicular or broadly obovate, often 5 mm. long; follicles 2, 
united nearly two-thirds their length, about 5 mm. long, flattened laterally, and somewhat 
keeled, dehiscent after falling; beaks straight, erect; seeds elliptic-pyriform, 1.5-2 mm. 
long ; caruncle small. 
TYPE LOCALITY: Shore of Lake Pend d’Oreille, northern Idaho 
DISTRIBUTION : Mountains, hillsides, and rocky banks, from British Columbia to Oregon, Utah, 
Wyoming, and Montana. 
ILLUSTRATION: Bot. Mag. pl. 7758 (as Netllia Torreyt). 
13. Opulaster alternans (M. E. Jones) Heller, Cat. N. Am. Pl. 
ed. 2: 5. 1900. 
Neila opulifolia pauciflora S. Wats. Bot. King’s Expl. 80, in part. 1871. 
Neillia opulifolia alternans M. E. Jones, Zoe 4: 42. 1893. 
Netllia alternans M. E, Jones, Zoe 4: 43, asasynonym. 1893. 
A low shrub, with divaricate branches; branches gray, finely stellate; petioles 0.5-1 cm. 
long; leaf-blades orbicular or reniform, about 1 cm. long, more or less deeply 3-lobed, doubly 
crenate, rounded or obtuse at the apex, usually cordate at the base, stellate-pubescent on 
both sides, densely so beneath ; corymbs few-flowered ; bracts oblanceolate, usually laciniate, 
caducous; pedicels 1 cm. or less long, densely stellate ; hypanthium stellate, 3-4 mm. wide ; 
sepals densely stellate on both sides, ovate, obtuse; petals white, rounded, ovate, about 3 
mm. long; follicles usually solitary, about 5 mm. long, densely stellate, beak erect. 
TYPE LOCALITY: Schell Creek Mountains, Nevada. 
DISTRIBUTION: Mountains of Utah and Nevada. 
Tribe 2. SPIRAEEAE. Shrubs, undershrubs, or herbs, with alternate 
leaves without stipules. Flowers racemose, corymbose, paniculate or solitary. 
Hypanthium hemispheric, campanulate, turbinate, or saucer-shaped. Disk 
more or less developed, bearing 15-70 stamens. Pistils normally 5, distinct ; 
ovules few. Seeds linear-lanceolate or oblong, pendulous, usually tapering at 
each end, with a thin seed-coat. Endosperm none or very scant. 
Stamens inserted on the margin of the hypanthium; flowers perfect; shrubs or undershrubs 
with simple leaves. 
Filaments free; leaves entire or toothed. 
Carpels dehiscent on the ventral suture; shrubs with deciduous leaves. 2. SPIRAEA. 
Carpels dehiscent dn both sutures; cespitose tufted undershrubs with per- 
sistent leaves. 
Flowers racemose, rarely somewhat paniculate ; stamens 20. 3, PETROPHYTUM. 
Flowers solitary, nearly sessile at the ends of the short branches; sta- 
mens 10. 4. KELSEYA. 
Filaments united at the base ; leaves twice or thrice 3-cleft. f 5. LUETKEA. 
Stamens inserted on the inside of the hypanthium ; flowers dioecious; tall 
herbs with twice or thrice compound leaves. 6. ARUNCUS. 
2. SPIRAEA L,. Sp. Pl. 489. 1753. 
Dimopogon Raf. Sylva Tell. 151. 1838. 
Xamedryon Raf. Sylva Tell. 151. 1838. 
Awayus Raf, Sylva Tell. 151. 1838. 
Shrubs of the northern hemisphere, with simple, feather-veined leaves, which are usu- 
ally serrate, and no stipules, Inflorescence racemose, corymbose or paniculate. Flowers 
in ours perfect. Hypanthium hemispheric, campanulate or turbinate. Sepals 5, valvate 
or slightly imbricate. Petals 5, imbricate or contorted, white to red. Stamens 15-70, 
inserted in 1-several series under the margin of a more or less developed disk; filaments 
subulate ; anthers didymous. Pistils 5, rarely 3,4, or 6-8, distinct, inserted in the bottom of 
the hypanthium; styles terminal; stigmas capitate or discoid; ovules 2~-several, anatropous, 
pendulous. Follicles leathery, not inflated, opening along the ventral side; seeds several, 
in ours usually 4, pendulous, linear-lanceolate or oblong, tapering at both ends; endo- 
sperm none or almost none. 
Type species, Spiraea salictifolia L. 
