ROSACEAE (ROSE FAMILY) 455 



* Mature carpels papery or soft-cartilaginous. 

 +- Cells of the compound ovary as many as the styles, without false or partial partitions. 



6. Pyrus. Fruit depressed -globose to ellipsoidal or obovoid ; its carpels enveloped in the fleshy 



receptacle, papery or soft-cartilaginous, usually 2-ovuled and 2-seeded. Leaves simple or 

 compound. 

 - +- Cells of the compound ovary subdivided by partial partitions projecting inward from the back. 



7. Amelanchier. Carpels usually 5. Leaves simple. Unarmed. 



* * Mature carpels very hard and bony, distinct or firmly coherent in the fleshy fruit. 



8. Crataegus. Ovules in each cell either solitary or if 2 unequal, one sessile and fertile, the 



other stalked and sterile. Shrubs and small trees, usually armed. Leaves simple, mostly 

 serrate or dentate, thin or coriaceous. 



9. Cotoneaster. Ovules 2 in each cell, equal. Armed shrub with coriaceous oval crenulate 



evergreen leaves. 



Tribe III. POTENTfLLEAE. Carpels few-many, l(-2)-ovuled, becoming dry achenes, not in- 

 closed at maturity. Chiefly herbs. 



* Styles not elongated after anthesis, mostly deciduous. 

 - Receptacle pulpy and much enlarged in fruit. 



10. Fragaria. Petals white. Leaves 3-foliate. Bractlets alternating with the calyx-lobes. Re- 



ceptacle juicy. 



11. Duchesnea. Petals yellow. Receptacle spongy, not juicy. 



+- +- Receptacle dry or nearly so, not greatly enlarged in fruit. 

 H- Stamens 5. 



12. Sibbaldia. Stamens alternate with the petals. Leaflets mostly 3-toothed at the end. 



13. Chamaerhodos. Stamens opposite the petals. Leaflets cleft into linear segments. 



H- -H- Stamens numerous. 

 = Carpels 1-ovuled. 



14. Waldsteinia. Achenes few, 2-6, rarely 10. 



15. Potentilla. Achenes numerous. Petals 5 (rarely 4), conspicuous. Calyx-lobes as many, 



with an alternating set of bractlets. 



= = Carpels 2-ovuled. 



16. Filipendula. Leaves pinnate ; stipules kidney-formed. 



* * Styles persistent and elongating after anthesis, often plumose or jointed. 



17. Geum. Calyx-lobes usually with 5 alternating small bractlets. Stamens and carpels numer- 



ous ; styles becoming plumose or hairy tails, or naked and straight or jointed. 



Tribe IV. RUBEAE. Pistils several or numerous, becoming drupelets in fruit. Ovules 2 and 

 pendulous, but seed solitary. Perennials, herbaceous or with biennial soft-woody stems. 



18. Rubus. Pistils mostly numerous, fleshy in fruit, crowded upon a spongy receptacle. 



19. Dalibarda. Pistils 5-10, in the bottom of the calyx, nearly dry in fruit. 



Tribe V. POTERlEAE. Pistils 1-4, becoming achenes, completely inclosed in the dry and firm 

 calyx-tube, which is constricted or nearly closed at the throat. Herbs with compound or lobed 

 leaves. Petals often none. 



20. Alchemilla. Calyx urceolate, bracteolate. Petals none. Stamens 1-4. Flowers minute, 



clustered. 



21. Agrimonia. Calyx top-shaped or bell-shaped, with a margin of hooked prickles. Stamens 



5-12. Flowers yellow, in long racemes. 



22. Sanguisorba. Calyx-lobes petaloid ; tube 4-angled, naked. Petals none. Flowers densely 



capitate or spicate. 



Tribe VI. R6SEAE. Pistils many, becoming bony achenes, inclosed in the globose or urn-shaped 

 fleshy calyx-tube, which resembles a pome. Petals conspicuous. Stamens numerous. 



23. Rosa. The only genus. Prickly shrubs with pinnate leaves. 



Tribe VII. PRlTNEAE. Ovary superior and not inclosed in the calyx-tube at maturity. Calyx 

 deciduous, without bractlets. Pistil solitary, becoming a stone-fruit. Ovules 2, but seed 

 almost always solitary. Style terminal. Trees or shrubs, with simple mostly serrate leaves. 



24. Prunus. Flowers perfect. Petals and calyx-lobes 5. Stone of the drupe bony. 



