164 ROSACEAE 



Follicles opening- along one suture : seeds dull or granular. 

 Pistils alternating with the sepals. 

 Flowers perfect : shrubs with simple leaf-blades. 2. Spiraea. 

 Flowers dioecious : herbs with 2-3-pinnate leaf-blades. 



3. Aruncus. 

 Pistils opposite the sepals. 



Follicles united at the base : leaf -blades pinnate : petals short. 



4. SORBARIA. 



Follicles distinct : leaf-blades 3-foliolate : petals elongated. 



5. PORTERANTHTJS. 



b. Pistils numerous or rarely few, maturing into achenes or 1-2-seeded drupe- 

 lets. 

 Pistils ripening into drupelets crowded on a receptacle. 

 Drupelets very juicy : fruit not in the calyx. 6. RUBUS. 



Drupelets dry : fruit enclosed in the calyx. 7. Dalibarda. 



Pistils ripening into achenes. 

 Style deciduous. 

 Style basal. ■ 8. Drymocallis. 



Style lateral. 

 Achenes pubescent : low shrubs. 

 Style club-shaped : corolla yellow : leaf -blades pinnate. 



9. Dasiphora. 

 Style filiform : corolla white : leaf -blades palmate. 



10. SiBBALDIOPSIS. 



Achenes glabrous : herbs. 

 Receptacle pulpy, edible : petals white. 11. Fragaria. 



Receptacle neither pulpy nor edible : petals yellow or red. 

 Leaf-blades 3-foliolate. 12. Duchesnea. 



Leaf-blades several-foliolate. 

 Corolla red. 13. Comarum. 



Corolla yellow. 14. Argentina. 



Style terminal or nearly so. 

 Pistils numerous : ovules pendulous : plants caulescent. 



15. POTENTILLA. 



Pistils 2-6 : ovules erect : plants acaulescent. 16. Waldsteinia. 

 Style persistent on the achene. 

 Pistils numerous. 17. GiUM. 



Pistils 5-15, at maturity resembling follicles but indehiscent. 



18. Ulmaria. 

 B. Fruit consisting of several achenes enclosed in the persistent hypanthium. 

 Achenes 1-4 within the dry hypanthium. 

 Receptacle bearing hooked prickles : petals 5. 19. Agrimonia. 



Receptacle without prickles : petals wanting. 20. Sanguisorba. 



Achenes numerous, within the fleshy hypanthium. 21. Rosa. 



1. OPULASTBR Medic. 

 1. Opulaster opulifoUus (L.) Kuutze. NinEbark. (Man. p. 492; 

 I. F. /. 1882.) On river banks and in rocky places, Quebec to Man., 

 Ga. and Kaus. — Pennsylvania : Northampton ; Bucks ; Chester ; Lan- 

 caster ; York ; Coi,dmbia ; Fui,ton ; Somerset ; Dei,aware ; Allb- 

 ghbny. 



