ROSACEAE 513 
Flowers perfect: shrubs with simple leaf-blades. 2. SPIRAEA. 
Flowers dioecious : herbs with 2-3-pinnate leaf-blades. 3. ARUNCUS. 
** Pistils opposite the sepals. 4. PORTERANTHUS. 
b. Pistils numerous or rarely few, maturing into achenes or 1-2-seeded drupelets. 
Pistils ripening into drupelets crowded on a receptacle. 
Receptacle flat: ovary pubescent above: drupelets crowned by a hairy 
cushion. 5. RUBACER. 
Receptacle convex or conic: ovary glabrous: drupelets glabrous. 6. RUBUS. 
Pistils ripening into achenes. 
Style deciduous. 
Style basal. 7. DRYMOCALLIS. 
Style lateral. 
Achenes pubescent : low shrubs. 8, SIBBALDIOPSIS. 
Achenes glabrous: herbs. 
Receptacle pulpy, edible: petals white. 9, FRAGARIA. 
Receptacle neither pulpy nor edible: petals yellow. 10. DUCHESNEA. 
Style terminal nearly so. 
Pistils numerous : ovules pendulous: plants caulescent. 11. POTENTILLA. 
Pistils 2-6: ovules erect: plants acaulescent. 12. WALDSTEINIA. 
Style persistent on the achene. 
Pistils numerous. 
Styles jointed, the upper part deciduous. 13. GEUM. 
, Styles not jointed. 14. SIEVERSIA. 
Pistils 5-15, at maturity resembling follicles, but indehiscent. 15. ULMARIA. 
B. Fruit consisting of several achenes enclosed in the persistent hypanthium. 
Achenes 1-4 within the dry hypanthium. 
Shrubs: leaf-blades simpie, merely toothed. 16. NEVIUSIA. 
Herbs : leaf-blades pinnate, or digitately lobed or divided. 
Receptacle accompanied by 4-5 braetlets. 17. ALCHEMILLA. 
Receptacle without bractlets. 
Receptacle bearing hooked prickles: petals 5. 18. AGRIMONIA. 
Receptacle without prickles: petals wanting. 19. SANGUISORBA. 
Achenes numerous, within the fleshy hypanthium. 20. Rosa. 
1. OPULASTER Medic. 
Wide-branching shrubs. Leaves alternate: blades simple, palmately lobed. Flowers 
perfect, white, in terminal corymbs. Hypanthium campanulate, or flattened in age. 
Sepals 5, persistent. Petals 5, spreading. Stamens numerous, 20-40. Disk clothing the 
hypanthium. Pistils 1-5, short-stalked: stigmas capitate. Ovules several. Follicles 
1-5, inflated, opening along both sutures. Seeds thick, 2-4 in each cavity, shining. Testa 
crustaceous. Endosperm copious. NINKBARK. 
Leaf-blades densely stellate-pubescent. 1. O. stellatus. 
Leaf-blades glabrous or sometimes slightły pubescent with simple hairs. 
Follicles 2-4, pubescent. 2. O. intermedius. 
Follicles mostly 5, glabrous. 3. O. opulifolius. 
. 1. Opulaster stellàtus Rydb. A low branching shrub, with decidedly pubescent 
foliage, the hairs mostly branched. Leaf-blades ovate to orbicular-ovate, 1-4 cm. long, 
slightly lobed and crenate, stellate-pubescent on both sides, especially so beneath, rounded 
at the apex or merely obtuse: inflorescence densely stellate-pubescent : follicles mostly 4, 
pubescent, about 5 mm. long. [Spiraea opulifolia var. ferruginea Nutt. ] 
In sand or sandy soil, Georgia and Florida. Spring. 
2. Opulaster intermédius Rydb. A much branched shrub, 1-1.5 m. tall, with 
sparingly pubescent foliage. Leaf-blades orbicular or broadly ovate, 2-6 cm. long, bluntly 
obed and crenate, rounded or subcordate at the base : pedicels, hypanthium and calyx 
finely pubescent : follicles 3 or 4, or rarely 2, pubescent, united below, 6-7 mm. long, rounded 
or obtuse at the apex. 
On river banks, South Dakota to Illinois, Alabama and Colorado. Spring. 
3. Opulaster opulifdlius (L.) Kuntze. A shrub, 1-3 m. tall, with wide-spreading or 
Tecurving branches, and glabrous or nearly glabrous foliage. Leaf-blades ovate to sub- 
orbicular, 3-8 cm. long, acutely 3-lobed, with unequally serrate margins, broadly cuneate 
i cordate at the base: corymbs 3-6 cm. broad: hypanthium glabrous or nearly so: fol- 
ae ie dni: shining, inflated, 8-10 mm. long, acute. [Physocarpus opulifolius (L.) 
In rocky soil and on river banks, Quebec to Kentueky and Georgia. Spring and summer. 
2. SPIRAEA L. 
: Shrubs or perennial herbs, usually with branching stems. Leaves alternate : blades 
simple, often lobed : stipules present. Flowers perfect, in terminal or axillary corymbs or 
panicles. Hypanthium turbinate, campanulate or urn-shaped. Sepals 4 or 5, erect or re- 
flexed. Petals 4 or 5, imbricated. Stamens 20-60.  Pistils usually 5, or sometimes 1-18, 
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