Davis : RANUNCULI OF NORTH AMERICA. 463 



papillose or spiny, borne in a head or spike ; styles minute or 

 elongated. 



In 1886 A. Gray wrote a revision of the North American 

 Ranunculi found north of northern Mexico. This was pub- 

 lished in Proc. Am. Acad. 21 : 363-378. In Syn. Flora I : 

 20-39, tne ^vision is brought down to 1895. Since that date 

 the list of species has rapidly increased and since Gray's first 

 revision two new North American genera have been segregated 

 from this one. In 1892 N. L. Britton discussed six species 

 " R. repens and its Eastern North American allies," Trans. N. 

 Y. Acad. Sci. 12 : 2-6. Britton and Brown's 111. Flora gives 

 31 species in eastern United States and Canada. In 1880 J. 

 Freyn gave a long treatment of about ten species in Flora, 63 : 

 179. 



The present treatment includes 96 species, eighteen of which 

 are found only in Mexico and south of there. 



TENTATIVE KEY TO SPECIES AND GROUPS OF SPECIES. 



A. Sepals and petals deciduous (except in 77) ? petals yellow or 

 white, with nectary on the claw covered by scale; sepals 5, 

 (rarely only 3 or 4) ; petals 5 or more; carpels not utricular 

 when mature, usually somewhat compressed. Sec. EURANUN- 

 CULUS, Gray. 

 B. Leaves, at least some of them, lobed or divided. 



C. Flowers yellow (except some cultivated forms of 31). 

 D. Plants terrestrial. 



E. Plants not spreading by rooting branches or stolons, ex- 

 cept in 12, 26 and 27. 

 F. Sepals glabrous or pubescent but not densely clothed 



with black or brown wool. 

 G. Akenes armed or clothed with prickles, spines or 



prominent papillae i. arvensis;2. muricatus; 



3. parviflorus ; 4. hebecarpus ; 5. Galeottii. 

 GG. Akenes nearly smooth or pubescent. 



H. Leaves, at least some of the radical ones, divided, 



the leaflets either sessile or stalked. 

 I. Radical leaves with some of the leaflets stalked. 

 J. Petals short, about the length of the sepals, 

 or shorter. 



K. Head of fruit globose 6. alceus. 



KK. Head of fruit oblong to cylindric. 



7. Pennsylvanicus. 

 JJ. Petals longer than the sepals. 



