126 ROSACEAE 



Prickles of the inflorescence not flattened, straightisli; leaflets dark 

 green above, acuminate, with small teeth; stem usually dark bluish, 

 with a bloom. 9. B. occidentalis. 



Prickles of the inflorescence strongly flattened and curved; leaflets 

 yellowish green above, acute, with coarse teeth; branches usually 

 straw-colored. 10. B. leucodermis. 



Inflorescence racemose; fruit red; leaves, when having more than 3 leaflets, 

 pinnately compound. 

 Plant not at all glandular-hispid; inflorescence with weak prickles, 

 villous. 11. iJ. melanotrachys. 



Plant more or less glandular-hispid, especially in the inflorescence. 

 Sepals narrowly lanceolate, gradually acuminate; leaves glabrate 

 beneath in age. 

 Stem sparingly bristly; leaflets neither strongly pUcate nor 



strongly veined. 12. B. peramoenus. 



Stem densely bristly; leaves strongly plicate and strongly veined. 



13. B. viburnifolius. 

 Sepals ovate or ovate-lanceolate abruptly acuminate. 



Young stems, petioles, and irflorescence neither densely tomen- 



tose nor puberulent. 14. B melanolasius. 



Young stems, petioles and inflorescence densely tomentose or 

 pubenilent. 15. B. dcalyphaceus. 



Carpels coherent to the fleshy receptacle; plant dioecious with decumbent stems 

 and 1-3-foUolate green leaves. 16. B. macropetalus. 



36. ROSA (Toiu-n.) L. Rose. 



Pistils numerous; styles as well as the upper part of the hypanthium persistent; sepals 

 in fruit erect or ascending, persistent. 

 Infrastipular prickles not present; branches mostly unarmed and young shoots bristly, 

 but not prickly. 

 Inflorescence corymbose, terminating the stems (or rarely the branches) ; plant 

 suftruticose; stem usually dying back to near the ground; leaflets 9-11. 

 Leaves glabrous or nearly so. 



Leaflets mostly 2-5 cm. long, not glaucous, decidedly acute; plant 3 dm. 



high or more; flowers corymbose. 1. B. arkansana. 



Leaflets rarely more than 2 cm. long, mostly rounded at the apex, some- 

 what glaucous beneath; plant 1-2 dm. high; flowers 1-3. 



2. B. Lunellii. 

 eaves densely pubescent, especially beneath. 

 Upper stipules and bracts not densely glandular; leaflets 1.5— J cm. long; 



plant 3-5 dm. high. 3. B. suffuUa. 



Upper stipules and bracts densely glandular; leaflets seldom more than 

 1.5 cm. long; plant 1-3 dm. high. 4. B. alcea. 



Inflorescence of solitary or few corymbose flowers at the end of lateral branches; 

 plant shrubby; leaflets usually 5 or 7, or 9 only on the young shoots. 

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

 tinct neck at the top. 

 Sepals rarely more than 1cm. long; bark yellowish green. 5. B. collaris. 

 Sepals 2-3 cm. long; bark brown. 



Leaflets con.spicuously glandular-granuUferous, but scarcely at all hairy 

 beneath, rounded-oval, double-toothed. 6. B. Engelmannii. 



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

 uliferous beneath, mostly elliptic, simple-toothed. 



7. B. acicularis. 

 Hypanthium subglobose, almost without a neck. 8. B. 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. 



Hypanthium densely prickly. 9. B. MacDougali. 



Hypanthium not prickly or rarely slightly so. 



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

 ous beneath; stipules and rachis glandular. 

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



not miu:iculate beneath. 10. B. nutkana. 



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

 muriculate beneath. 11. B. muriculata. 



Leaflets simple-toothed, puberulent but not glandular-granuliferous 

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



Prickles more or less distinctly curved. 

 Hypanthium prickly. 



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



13. B. Underwoodii. 

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



2 cm. long. 16. B. aciculata. 



Hypanthium smooth. 



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



14. B. Durandii. 

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

 spicuously glandular, mostly glabrous. 



Leaflets perfectly glabrous or merely glandular-granuliferous be- 

 neath. 



