53. ROSACEAE 1 1 1 



tary; fruit 8-10 mm in diameter, 3- to 4-seeded; plants usually 

 low and trailing; thickets and along fences, local; Cook, Du 

 Page, Kane, Lake, McHeniy, Stephenson, and Winnebago 

 counties. June-July. Woodbine P. vitacea (Knerr) Hitchc. 



53. Rosaceae Juss. — Rose Family 

 [Malaceae Small; Drupaceae DC.) 

 1. Trees and shrubs. 



2. Pistils se\eral to many, simple, or pistil apparently one, compound. 

 3. Pistils 2-many, simple, superior; fruits achenes, drupelets, or follicles. 

 4. Pistils 2-5, each becoming a 2- to 4-seeded follicle; shrubs with 

 simple, serrate to entire, or slightly lobed leaves. 

 5. Leaves palmately shallowly lobed; carpels 2-5, somewhat inflated 

 at maturity; pubescence of stellate hairs 1. Physocarpus 



5. Leaves serrate to entire; carpels 5-8, not inflated; pubescence of 



simple hairs, or plant glabrous 2. Spiraea 



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

 or drupelet. 



6. Leaflets or leaves serrate. 



7. Flowers white or purple (in our species) ; leaves palmately 

 compound (simple in one species), the stipules not adnate to 

 the petiole; fruit an aggregate of 1 -seeded drupelets forming 



a blackberry or raspberry 11. Rubus 



7. Flowers rose (in our species) ; leaves pinnate (rarely 3-folio- 

 late), the stipules adnate to the petiole: fruit of seed-like 



achenes enclosed in the hypanthium (calyx-tube) 12. Rosa 



6. Leaflets entire, silky-pubescent: flowers yellow (species of) 



6. Potentilla 



3. Pistil apparently 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. Leaves entire 14. Cydonia 



10. Leaves serrate, crenate, or lobed. 



ll.Midvein of the leaves with small dark-colored glands on 

 the upper surface; margins glandular-crenulate : flowers 

 in compound cymes: anthers purple; styles united 

 below: fruit small, berry-like; endocarp of the ripe 



carpels leathery 16. Aronia 



ll.Midvein not glandular; margins not glandular-crenulate. 



12. Inflorescence cymose; endocarp of the ripe carpels 



cartilaginous. 



13. Styles free; orifice of the receptacle clo.sed by the 



disk; anthers pink or red; fruit containinu; 



numerous stone-cells 17. Pyrus 



13. Styles united below the middle; orifice of the 

 receptacle open; anthers white or yellow; fruit 

 without stone-cells 13. Mains 



