148 American Midland Naturalist Monograph No. 2 



4. Pistils numerous, or rarely few. each becoming a 1 -seeded achene or drupelet. 

 6. Branches usually with prickles; leaflets serrate. 



7. Flowers white (in our species) ; leaves palmately compound, the stipules 

 not adnata to the petiole; fruit an aggregate of 1 -seeded drupelets form- 

 ing a blackberry or raspberry II. Rubiis 



7. Flowers rose (in our species) ; leaves pinnate (rarely 3-foliolate), the 

 stipules adnate to the petiole; fruit of seed-like achenes enclosed in the 

 hypanthium (calyx-tube) 12. Rosa 



6. Branches not prickly; leaflets entire, silky-pubescent; flowers yellow (species 

 of) 6. Potenlilla 



3. Pistil 1, compound, inferior, enclosed by the calyx-tube; styles 2-5; fruit a pome. 

 8. Leaves simple. 



9. Flowers in racemes; petals narrow; fruit small, berry-like, sweet, with thin 



pulp, its locules twice as many as the styles; branches not spiny 



13. Amelanchier 



9. Flowers in cymes or corymbs; petals roundish; locules of the fruit (carpels) 

 the same number as the styles. 

 10. Midvein of the leaves with small dark colored glands on the upper sur- 

 face; margins glandular-crenulate ; flowers in compound cymes; anthers 

 purple; styles united below; fruit small, berry-like; endocarp of the 



ripe carpels leathery 1 5. Arouia 



10. Midvein not glandular; margins not glandular-crenulate; fruit large, 

 fleshy. 

 I 1 . Inflorescence cymose; endocarp of the ripe carpels cartilaginous. 

 12. Styles free; orifice of the receptacle closed by the disk; anthers 



pink or red; fruit containing numerous stone-cells 



- 16. P\}rus 



12. Styles united below the middle; orifice of the receptacle open; 



anthers white or yellow; fruit without stone-cells 17. Mains 



I 1 . Inflorescence corymbose; styles free; endocarp of the ripe carpels 



hard and bony; branches usually with spines 18. Crataegus 



8. Leaves pinnate; flowers in terminal compound cymes; petals roundish; styles 3, 

 free; anthers white; pome small, berry-like, red, acid, 3-lcculed; branches 



not spiny 14. Sorhus 



2. Pistil 1, simple, superior, 2-ovuled; style I; fruit a I -seeded drupe; leaves simple 

 19. Pnirnis 



I. Herbs; pistils several to many, simple, superior; fruit achenes, drujjelets, or follicles. 

 13. Pistils 2-5, becoming 2-4-seeded follicles. 



14. Leaves trifoliolate or 3-parted, nearly sessile; stipules large; flowers white or 



pinkish, in loose terminal panicles 4. Cillenia 



14. Leaves pinnately compound. 



15. Leaves 2-3-pinnate; stipules minute or none; flowers numerous, unisexual, 

 in a large panicle; petals white, about 1 mm. long; follicles reflexed, 



usually 2-seeded 3. Aruncus 



15. Leaves pinnately 3-9-lobed or -foliolate; flowers perfect, pink or purple, 

 in dense cymose panicles 7. FilipcnJula 



13. Pistils one to many, becoming 1 -seeded achenes or drupelets. 



16. Pistils ripening into pulpy drupelets, forming a red raspberry; style terminal or 

 nearly so; leaves 3-5-foliolate ; petals white or pink 11. Ruhus 



16. Pistils ripening into achenes. 

 17. Calyx not bristly. 



18. Pistils several to many; petals present; calyx usually with 5 sepal-like 

 bractlets alternating with the sepals. 

 19. Style deciduous from the mature achene. 



20. Receptacle becoming succulent, red (or white), and edible in 

 fruit (a strawberry); petals white (or pink), obtuse: leaves 



trifoliolate 5. Fragaria 



20. Plants not as above 6. Potenlilla 



