172 FLORA OF PHILADELPHIA. 



Family 11. ROSACEAE B. Juss. Rose Family. 



Fruit not enclosed in a hollow receptacle, the so-called calyx. 



Pistils few, seldom more than 5, ripening into 2-4-seeded follicles. 

 Follicles dehiscent along both sutures ; seeds shining. 



1. Opulaster. 

 Follicles dehiscent along one suture ; seeds dull. 



Pistils alternate with the calyx-lobes. 2. Spiraea. 



Pistils opposite the calyx-lobes, petals white. 3. Porterantlius. 

 Pistils numerous or rarely few, ripening into 1-2-seeded drupelets or 

 achenes. 

 Pistils ripening into drupelets crowded on the receptacle. 



Drupelets very pulpy. 4. Bub us. 



Drupelets nearly dry, enclosed by the calyx. 5. Dalibarda. 

 Pistils ripening into achenes. 

 Style deciduous. 



Style nearly basal ; ovules ascending or nearly erect, ortho- 



tropous ; leaves pinnate. 6. Drymocallis. 



Style lateral; ovules ascending and amphitropous. 



Receptacle much enlarged and red in fruit ; leaves 

 trifoliolate. 

 Receptacle pulpy, edible; petals white. 



7. Fragaria. 

 Receptacle not pulpy; petals yellow. 



8. Diichesnea. 

 Receptacle not enlarged in fruit ; leaves interruptedly 



pinnate; petals yellow. 9. Argentina. 



Style terminal or nearly so. 



Pistils numerous ; ovules pendulous and anatropous. 



10. Potentilla. 

 Pistils 2-6 ; ovules basal, erect. 11. Waldsteinia. 



Style persistent on the aehene. 12. Geum. 



Fruit 1-4 achenes, enclosed in the persistent, dry receptacle ; herbs. 



Calyx bearing hooked prickles ; petals 5. 13. Agrimonia. 



Calyx not prickly ; petals none. 14. Sanguisorha. 



Fruit, numerous achenes, enclosed in the fleshy receptacle ; shrubs with pin- 

 nate leaves. 15. Bosa. 



1. OPULASTER Medic. 

 1. Opulaster opulifolius (L.) Kuntze. Ninebarl'. M. p. 492. Rocky 

 banks of streams ; often cultivated. Early summer. 



2. SPIRAEA L. 



Glabrous or nearly so throughout. 1. S. salicifolia. 



Twigs and lower surfaces of the leaves woolly-pubescent. 2. S. tomentosa. 



1. Spiraea salicifolia L. Meadoio-sweet. M. p. 492. Wet or low grounds. 



Summer. 



2. Spiraea tomentosa L. Hardhack, Steeple-bush. M. p. 492. Low 



grounds. Summer. 



3. PORTERANTHUS Britton. 



1. PoRTERANTHus TRiFOLiATUS (L.) Britton. Indian-physic, Boxoman's-root. 



M. p. 493. Rich woods. Summer. 



P7wtodeZp7wa— Wissahickon (Me.) (Re.) (Te.), Fairmount Park (Wn.), 



Bucl's—Krgvis (Fr.), Lumberton, Delaware shore (Ws.). Montgomery 



— Shannonville (Cr.), Mill Creek, Walnut Hill (VP.). Delaxcare — 



Media (Gi.) (Ws.), Wawa (Ja.) (U. C. S.), Valley of Darby Creek (B. 



