ROSACEAE 513 



D^' n D\o r\ 



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 simple, merely toothed. 16. NEVIUSIA. 



Herbs : leaf-blades pinnate, or digitately lobed or divided. 



Receptacle accompanied by 4-5 bractlets. 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. NINEBARK. 



Leaf-blades densely stellate-pubescent. 1. 0. itettatua. 

 Leaf-blades glabrous or sometimes slightly pubescent with simple hairs. 



Follicles 2-4, pubescent. 2. 0. intermedius. 



Follicles mostly 5, glabrous. 3. 0. opulifolius. 



1. Opulaster stellatus 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 iiitermedius 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 

 lobed 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 opulifolius (L.) Kuntze. A shrub, 1-3 m. tall, with wide-spreading or 

 recurving 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 

 to cordate at the base : corymbs 3-6 cm. broad : hypanthium glabrous or nearly so : fol- 

 licles 5, glabrous, shining, inflated, 8-10 mm. long, acute. [Physocarpus opulifolius (L. ) 

 Maxim.] 



In rocky soil and on river banks, Quebec to Kentucky 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, 

 33 



