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1896] ROS AMERICANA. 33 
6 Annual stems often transformed into false flower-bearing branch- 
lets with leaves 9 to 11-foliate, or normal flowering branchlets 
densely setigerous - - R. Arkansana Porter 
Annual stems not transformed into false ath ae branchlets ; 
normal flowering branchlets with prickles more or less rare 
R. blanda Ait. 
7 Corolla very small (15 to 20™™ in diameter) ; calyx detaching itself 
in a single piece yop: ba ote: the receptacle open 
at summit RR. gymnocarpa Nutt. 
Corolla more than 20™™ in diameter; sepals erect upon the fruc- 
tiferous and persistent receptacles - - - 8 
8 Upper stipules and bracts narrow; sepals usually silky outside, 
R. Californica Cham. & Schlecht. 
Upper stipules and bracts more or less large; sepals not silky 9 
9 Upper stipules and bracts much dilated ; inflorescences often one- 
flowered ; corolla usually large; fructiferous receptacles large, 
remaining quite dry at maturity, with large akenes; leaflets 
often glandular beneath and with glandular compound teeth 
R. Nutkana Pres] 
Upper stipules and bracts moderately dilated ; inflorescences often 
'many-flowered ; corolla quite small or middle-sized ; fructifer- 
ous receptacles small or middle-sized; leaflets usually without 
glands beneath, and with simple teeth - - - 10 
10 Leaflets oval, more or less rounded at base, with open teeth ; fruc- 
tiferous receptacles often small ; corolla quite small 
R. pisocarpa A. Gray 
Leaflets obovate, narrowed or cuneate at base, with teeth, directed 
toward the apex; fructiferous ee ee or middle- 
sized ; corolla quite large - R. blanda Ait 
11 Paired prickles with tips more or less curved or hooked ; upper 
stipules and bracts narrow; receptacles nearly always smooth, 
R. Californica Cham, & Schlecht. 
Paired prickles straight ; upper stipules and bracts more or less 
dilated, rarely narrow - - - - Te: 
12 Bushes very small, a few inches in height and not surpassing a 
foot ; upper stipules and bracts narrow; corolla very small, not 
exceeding 20™" in diameter; uae often glandular- 
wap R. spithamea Wats. 
