ROSE FAMILY 403 



glabrous or stellate on both sides, thin, 2-6 cm. long and about as broad; bracts 

 spatulate or cuneate, caducous; sepals ovate, 4-5 mm. long; petals often 5 mm. 

 long; follicles 2, united nearly two-thirds their length, about 5 mm. long, dehiscent 

 after falling. O. pubescens Rydb. P. malvaceus Kuntze. P. pubescens Coult. &. 

 Nels. Mountains, hillsides, and rocky banks: B.C. — Ore. — Utah — Wyo. — Mont. 

 Suhmont.^Mont. My-Jl. 



9. O. alternans (M. E. Jones) Heller. Low shrub, with divaricate, gray, 

 finely stellate branches; blades orbicular or reniform, about 1 cm. long, more 

 or less deeply 3-lobed, doubly crenate, rounded or obtuse at the apex, stellate- 

 pubescent on both sides, densely so beneath; bracts oblanceolate, usually lacini- 

 ate, caducous; sepals densely stellate on both sides, ovate, obtuse; petals about 

 3 mm. long. Niellia alkrnans M. E. Jones. Mountains: Utah — Nev. Submont. 

 —Mont. Je-Jl. 



2. SPIRAEA L. Meadow Sweet. 



Shrubs, with simple, feather-veined leaves, which are usually serrate, and no 

 stipules. Inflorescence racemose, corymbose or paniculate. Flowers in ours 

 perfect. Hypanthium hemispherical, campanulate, or turbinate. Sepals 5, 

 valvate or shghtly imbricate. Petals 5, imbricate, white to red. Stamens 

 15-70, inserted in 1-several series under the margin of a more or less developed 

 disk. Pistils 5, rarely 3-S, distinct, inserted in the bottom of the hypanthium; 

 styles terminal; stigmas capitate or discoid; ovules 2-several, anatropous, pendu- 

 lous. Follicles leathery, not inflated, opening along the ventral suture; seeds 

 several, in ours usually 4, pendulous, linear-lanceolate or oblong, tapering at 

 both ends; endosperm none or almost none. 



Panicle flat-topped; sepals erect or merely spreading. 



Petals pink or rose-colored ; corymb small. 1. S. densiflora. 



Petals white, seldom tinged with rose; corymb larger. 2. 5. lucida. 



Panicle elongate, conical or ovoid, or lanceolate. 

 Sepals merely spreading; disk obsolete. 



Inflorescence glabrous; leaf-blades broadly oblanceolate to obovate. 



3. S. laiifolia. 

 Inflorescence pubescent; leaf-blades narrowly oblanceolate. 4. S. alba. 



Sepals soon reflexed; disk usually rather conspicuous. 

 Leaves not tomentose beneath. 



Stem glabrous; leaves serrate to near the base. 5. S. idahoensis. 



Stem more or less pubescent; leaves toothed above the middle. 



6. S. Menzicsii. 

 Leaves tomentose beneath. 7. S.Duuglasii. 



1. S. densiflora Nutt. Low shrub, 2-6 dm. high, with ascending branches; 

 bark of the twigs dark reddish brown, glabrous; leaf-blades oval or elliptic, 

 rounded at both ends, glabrous or essentially so, bright green above, somewhat 

 paler beneath, crenate or serrate above the middle, 1.5-3 cm. long; sepals ovate, 

 obtuse; petals nearly 1.5 mm. long, obovate; folUcles glabrous and shining. 

 Mountains: B.C. — -Ore. — -Wyo. — Mont. Submont. — Mont. Jl-Au. 



2. S. lucida Dougl. Low shrub, with creeping rootstock; stems and branches 

 erect, often dying down annually to near the base, 3-10 dm. high; blades of the 

 lower leaves obovate, of the upj)er oval, often acutish, 2-6 cm. long, thin, gla- 

 brous, shining above, paler beneath, coarsely serrate or incised; sepals triangular, 

 acute; petals white, orbicular, about 2 mm. long; follicles glabrous, shining. 

 Mountains: B.C. — -Ore. — -Wyo. — -Sask. Submont. — Mont. My-Jl. 



3. S. latifolia (Ait.) Borkh. A shrub, 1-20 dm. high, branched; bark of the 

 twigs glabrous, chestnut; leaf-blades broadly oblanceolate or obovate, thin, 2-8 

 cm. long, acute, obtuse or rounded at the apex, sharply and sometimes doubly 

 serrate; inflorescence 0.5-2 dm. long and about haK as wide; bracts sometimes 

 ciliate; sepals triangular, acute; petals white or a little pinkish in bud; follicles 

 glabrous and shining. Meadows: Newf. — -N.C. — w Pa. — Sa.sk. Boreal. Je-S. 



4. S. alba DuRoi. A shrub, 1-2 m. high; bark of the twigs brown; leaf- 

 blades rather firm, more or less puberulent on the veins, sharply serrate, acute 

 at both ends, 3-6 cm. long; inflorescence 5-20 cm. long; sepals triangular, acute; 

 petals white, about 2 mm. long; foUicles glabrous, shining. S. simplex Greene. 

 Swamps and wet ground: Newf. — N.C. — -la.— N.D. — Sask. Boreal. Je-Au. 



