OF ARTS AND SCIENCES. 337 



4. R. minutifolia. 



5. R. Carolina. 



6. R. humilis. (i?. lucida, R. mtida.) 



7. R. foliolosa. (R. iMexicana.) 



8. R. setigera. 



9. R. gymnocarpa. 



A synopsis of tlie grouping and differentiation of the species, as here 

 adopted, may be made as follows, exceptions being disregarded : — 



Synopsis of Species. 



I. — Sepals connivent and persistent after flowering. 



A. — Without infrastipular spines ; acicular prickles often present. Pedicels 



and receptacles naked. 

 * Fruit oblong. Arctic, 



1. R. AcrcuLARis. Stipules dilated ; leaflets usually 5, obtuse or cordate at 



base, not resinous : flowers solitary ; sepals entire, not hispid. — Northern 



Alaska. 



* * Fruit globose. More southern. 



2. K. BLAXDA. Prickles usually few or none : stipules dilated ; leaflets 5 or 7, 

 cnneate at base and petiolniate, simply toothed, not resinous ; flowers corym- 

 bose or solitary; sepals hispid, entire. — Newfoundland to Lake Superior. 



3. R. Sati. Very prickly : stipules dilated ; leaflets 5 or 7, sessile and obtuse 

 or subcordate at base, resinous and doubly toothed : flowers solitary ; outer 

 sepals laterally lobed, not hispid. — Colorado to British America and Lake 

 Superior. 



4. R. Arkaxsaxa. Very prickly: stipules narrow; leaflets 7 to 11, sub- 

 cuneate at base, simply tootlied, not resinous: flowers corymbose; sepals not 

 hispid, the outer lobed. — Western Texas to British America. 



B. — Infrastipular spines present, often with scattered prickles. 

 * Pedicels and receptacles naked. Leaflets 5 or 7. 

 •1- Sepals entire. 

 ++ Flowers and fruit large, solitary. Stipules dilated. 



5. R. Ndtkana. Spines stout, straight or recurved : leaflets rounded at base : 

 fruit globose. — Alaska to Oregon and Idaho. 



++ ++ Flowers and fruit corymbose or solitary, smaller. Stipules short and 



narrow. 



6. R. pisocARPA. Spines straight, slender, ascending or spreading: leaflets 

 rounded or subcuneate at base: fruit globose, small. — Oregon and Washing- 

 ton Territory. 



7. R. Califorxica. Spines stout, straight or recurved : leaflets obtuse at 

 both ends, often villous, as also the pedicel and receptacle : fruit ovate, with a 

 prominent neck. — Oregon to Lower California. 



8. R. Fexdleri. Spines straight or recurved : leaflets cuneate at base, not 

 villous : fruit globose. — From the Sierra Nevada and Cascades to the Rocky 

 Mountains. 



VOL. XX. (x. s. XII.) 22 



