440 ROSACEAE 



Hypanthium decidedly pear-shaped or elliptic, acute at the base, with a dis- 

 tinct neck at the top. 

 Sepals rarely more than 1 cm. long; bark yellowish green. 5. R. coUaris. 

 Sepals 2-3 cm. long; bark brown. 



Leaflets conspicuouslj' glandiilar-granuliferous, but scarcely at all hairy 

 beneath, rounded-oval, double-toothed. 6. R. Engelmannii'. 



Leaflets densely pubescent, but rarelj slightly if at all glandular-gran- 

 uliferous beneath, mostly elliptic, simple-toothed. 



7. R. acicularis. 

 Hypanthium subglobose, almost without a neck. 8. R. Bourgeauiana. 



Infrastipular prickles usually present. 



Flowers mostly solitary: petals usually 2.5 cm. long or more; fruit 12-20 mm thick. 

 Prickles straight or nearly so. 



Hypantliium densely prickly. 9. R. MacDougali. 



Hypantliium not prickly or rarely slightly so. 



Leaflets more or less double-toothed, more or less glandular-granulifer- 

 ous beneath; stipules and racliis glandular. 

 Leaflets very thin, pale and slightly glandular-granuliferous, but 



not muriculate beneath. 10. R. nutkana. 



Leaflets thicker, dark green on both sides, conspicuously glandular- 

 muriculate beneath. 11. R. muriculata. 



Leaflets simple-toothed, puberulent but not glandular-granuliferous 

 beneath; rachis rarely glandular. 12. R. Spaldingii. 



Prickles more or less distinctly curved. 

 Hypantliium prickly. 



Stem stout, 1 m. high or more; leaflets usually more than 3 cm. long. 



13. R. Underwoodii. 

 Stem low, usually less than 3 dm. high; leaflets usually not more than 



2 cm. long. 16. R. aciculata. 



Hypanthium smooth. 



Prickles very large and flat; twigs densely glandular and pubescent. 



14. R. Durandii. 

 Prickles short and slender, not conspicuously flattened; twigs not con- 

 spicuously glandular, mostly glabrous. 



Leaflets perfectly glabrous or merely glandular-granuliferous be- 

 • neath. 



Stem 1 m. high or more; leaflets usuallj^ more than 2 cm. long, 

 pale or light green, rather Arm, rarely double-serrate, not 

 glandular-granuliferous beneath; calyx not densely glandular. 



15. R. niclina. 

 Stem usually less than 3 dm. high; leaflets usually less than 2 



cm. long, dark green, glandular-double-toothed; calyx usually 

 covered with stalked glands. 16. R. aciculata. 



Leaflets sparingly pubescent beneath. 17. R. oreophila. 



Flowers mostly corymbose, if solitary the petals 2 cm. long or less; fruit rarely 

 more than 1 cm. thick. 

 Prickles more or less curved. 



Leaflets finely puberulent or glandular-granuliferous, or both beneath. 



Hypantliium ellipsoid; young shoots with rather few strong curved 



prickles. 18. R. neortiezicana. 



Hypantliium globose; young shoots with fine, often rather many prick- 

 les. 19. R. puberulenta. 

 Leaflets perfectly glabrous. 20. R. manca. 

 Prickles straight or nearly so. 



Hypanthium globose; neck usually obsolete. 



Stipules, petioles, and rachis conspicuously glandular. 



21. R. Fcndleri. 

 Stipules, petioles, and rachis not conspicuously glandular, usually 



glandless. 

 Leaflets glabrous or nearly so. 



Leaves yellowish green; fruit orange; corymb several-flowered. 



22. R. chrysocarpa. 

 Leaves dark green above, paler beneath; fruit purplish red; 



flowers 1-3. 23. R. Woodsii. 



Leaflets more or less pubescent beneath. 



Leaflets elliptic or oval, equally green on both sides. 



Leaflets broadly oval, thin, 2-5 cm. long; plant nearly un- 

 armed. 24. R. salictorum. 

 Leaflets narrowly oval, less than 3 cm. long, rather firm: 

 plant prickly. 25. R. ultramontana. 

 Leaflets obovate, or if elliptic, .more or less glaucous beneath. 

 Leaflets tliin, very sharply serrate, equally green on both 

 sides; sepals with a few slender bristles near the margins; 

 prickles very slender. 26. R. praetincta. 

 Leaflets firmer, paler beneath; sepals without bristles; prickles 

 stouter. 27. R. Macounii. 

 Hypanthium elongate, pear-shaped, with a distinct neck. 



28. R. pyrifera. 

 Pistils few; styles deciduous with the upper part of the hypanthium, which falls ofif as a 

 ring. 



