Par? 3, 1908] ROSACEAE 241 
Carpels 8-10 mm. long, rather gradually acute ; leaves of the sterile 
shoots often 5-lobed. 2. O. capitatus. 
Carpels 3-6 mm. long, abruptly acute; leaves of the sterile shoots 
3-lobed. 3. O. australis. 
Mature carpels stellate, short-ellipsoid, abruptly acute, usually 3 or 4; 
caruncle short. 
Branches glabrous; leaf-blades of the sterile shoots cordate or rounded- 
ovate, 
Leaf-blades deeply lobed, as broad as long, cordate at the base ; west- 
ern species. 4. O. cordatus, 
Leaf-blades shallowly round-lobed, not cordate at the base, usually 
longer than broad ; eastern species. 5. O. intermedius. 
Branches more or less hairy or stellate, especially when young. 
Leaf-blades of the sterile shoots ovate in outline, more or less acumi- 
nate, sparingly pubescent. 6. O. alabamensis. 
Leaf-blades of the sterile shoots round-ovate, merely acute, densely 
stellate. 7. O, stellatus. 
Carpels 2, united half their length, or only 1. 
Carpels usually 2; stamens similar or nearly so. 
Mature carpels more or less turgid; styles more or less spreading. 
Bracts obovate or spatulate, often foliaceous and more or less per- 
sistent. 8. O. bracteatus. 
Bracts linear or linear-oblanceolate, membranous and caducous. 
Pedicels and hypanthium almost glabrous; sepals stellate only 
on the inner surface and near the margin; shrub 1 m. high or 
more. 9. O. glabratus. 
Pedicels, hypanthium, and calyx densely stellate; shrub 0.5 m. 
high or less. 
Leaves green on both sides, almost glabrous. 10. O. monogynus. 
Leaves paler and densely stellate beneath. 11. O. Hapemanit. 
Mature carpels flattened and decidedly keeled ; styles erect. 12. O. malvaceus. 
Carpels usually solitary; alternate filaments longer and with more dilated 
base ; leaves small, finely stellate. 13. O. alternans. 
1. Opulaster opulifolius (1,.) Kuntze, Rev. Gen. 949. 1891. 
Spiraea opulifolia I,. Sp. Pl. 489. 1753. 
Opulaster bullatus Medic. Pfl. Anat. 109. 1799, 
Physocarpa riparia Raf. New F1.3: 73. 1838. 
Physocarpa opulifolia Raf, New F1.3: 73, in part. 1838. 
Neillia opulifolia Brewer & Wats. Bot. Calif. 1: 171. 1876. 
Physocarpus opulifolia Maxim. Acta Hort. Petrop. 6: 220. 1879. 
Physocarpus michiganensis Daniels, Univ. Missouri Stud. Sci. 1: 291. 1907. 
A shrub, 1-3 m. high, much branched; the old bark peeling off in layers; branches 
glabrous or nearly so; leaf-blades of the flowering branches usually ovate, varying from 
oblong-ovate to almost orbicular, glabrous except sometimes the veins and their axils, 2-7 
em. long, 1.5-6 cm. wide, usually shallowly or indistinctly 3-lobed, but sometimes resemb- 
ling those of the sterile shoots, acute, rounded or subcordate at the base, doubly crenate, 
acute, obtuse or rounded at the apex; leaf-blades of the sterile shoots usually larger and 
more deeply lobed, 6-10 cm. long, usually subcordate at the base, acute or somewhat acu- 
minate at the apex ; corymb open; bracts spatulate or oblanceolate, early caducous; pedicels 
1-2 cm., in fruit 2-3 cm. long, glabrous or stellate-pubescent ; hypanthium about 4mm. wide, 
stellate or glabrate; sepals ovate, acute, about 3 mm. long, sparingly stellate or glabrate 
without, densely white stellate-tomentose within ; petals orbicular or broadly obovate, 34 
mim. long, white or pinkish; follicles usually 5, in age perfectly glabrous, 8-10 mm. long, 
ovate, rather long-acuminate; seed obliquely pear-shaped, nearly 2 mm. long; caruncle 
long, about one-third as long as the seed. 
TYPE LOCALITY: Virginia. : 
DISTRIBUTION : Rocky river banks, from Quebec to Virginia, Tennessee, and Michigan. 
ILLUSTRATIONS: Ann. Sci. Nat. 1: f/. 17; Nouv. Duham. pi: 14; Loud. Arb. pl. 427, 428; 
Britt. & Brown, Ill. Fl. /. 2882. 
2. Opulaster capitatus (Pursh) Kuntze, Rev. Gen. 2: 949. 1891. 
Spiraea capitaia Pursh, Fl. Am. Sept. 342. 1814. 
Spiraea dpulifolia tomentella Seringe, in DC. Prodr. 2: 542. 1825. 
Spiraea opulifolia B Hook. F1. Bor. Am.1: 171. 1832. 
Physocarpa tomentosa Raf. New F1.3: 74. 1838. 
Spiraea opulifolia mollis T. & G. Fl. N. Am. 1: 414, 1840. 
Neillia opulifolia mollis Brewer & Wats. Bot. Calif. 1: 171. 1876. 
Neillia capiiaia Greene, Pittonia 2: 28. 1889. 
