RANUNCULACEAE (BUTTERCUP FAMILY) lOl 



RANUNCULUS (Buttercup) 



Herbs, annual or perennial, mostly in wet places, sometimes aquatic. 

 Leaves simple or compound. Sepals 5, deciduous. Petals as many as 

 the sepals or more, conspicuous or minute, with a scale at the base of the 

 blade. Stamens several to many. Akenes many; style minute or elon- 

 gated. — (Diminutive of L. rana = a frog; on account of the common wet 

 habitat.)' 



A. Plants aquatic or subaquatic; leaves divided into filiform segments when sub- 

 merged. 



B. Petals much exceeding the sepals; carpels margined toward the base with con- 

 spicuous tumid border. E. R. delphinifoUus (swamp buttercup) 



BB. Petals not much exceeding the sepals; carpels without distinct border, W. C. 

 E. R. purshii (pursh buttercup) 



AA. Plants terrestrial but often of very wet places; leaves never dissected into fili- 

 form segments (except R. sceleratus) . 



C. Leaves entire to crenate or dentate, not lobed nor more deeply separated into 

 segments. 



D. Leaves ovate to cordate, coarsely crenulate to dentate. 



E. Leaves acute, dentate; mature akenes not veined on the faces. E. 



R. gormani 

 EE. Leaves rounded at apex, crenate; mature akenes striate-veined on the faces. 

 W. E. R. cymbalaria (seaside buttercup) 



DD. Leaves either narrower or else merely crenulate or denticulate. 



F. Stem creeping, rooting from the joints. W. C. E. R. flammula (spearwort) 

 FF. Stem erect, not rooting from the joints. C. E. R. alismaefolius 



CC. Leaves or some of them lobed or yet more deeply separated into segments. 

 G. Faces of the akenes smooth or merely pilose; mostly perennials. 

 H. Plants glabrous or nearly so, 3 dm. or less high or long (except R. sceleraius 

 and R. bongardii). 



I. Basal leaves toothed or entire or 2-7-lobed for less than J the distance to the 

 base; stem leaves 2-5-cleft or -parted. 



J. Basal leaves 2-4-toothed or -lobed; carpels forming a globose head. 



K. Blades of basal leaves widest above their middle; petals broadly obovate- 



E. R- glaberrimus 



KK. Blades of basal leaves widest below their middle; petals spatulate-oblong. 



E. R- jovis 



JJ. Basal leaves s-9-lobed at apex, carpels forming an oblong or cylindric head. 



E. R- eximius 



II. Both basal and stem leaves parted or divided or compound. 



L. Leaves ternately divided; the segments linear to linear-spatulate, 1-2 mm. 

 wide. E. R- tritematus 



LL. Leaves not so in every particular. 

 M. Head of akenes globose. 

 W. Beak of the akene hooked. 

 O. Segments of basal leaves again deeply lobed. (See D.) 

 00. Segments of basal leaves not again lobed. E. R. jovis 



NW. Beak of the akene without hook. 

 P. Petals 2-4 mm. long. W. E. — Very poisonous to cattle. 



R. sceleratus (cursed buttercup) 

 PP. Petals 8-13 mm. long. W. C. R. suksdorfii 



MM. Head of akenes 2 or more times as long as wide. 



