466 Ranunculaceae Ranunculus 



margined at the base, the beak about half the length of the body of the 



achene 1. R- flabellaris. 



Leaves of submerged plants on petioles more than 1 cm long, the segments obtuse; 

 achenes not margined, the beak about a third as long as the body of the 



achene. (See excluded species no. 241, p. 1049.) R. Purshii. 



Flowers white. 



Leaves petiolate, 2-2.5 cm long, collapsing when taken from the water 



2. R. trichophyllus. 



Leaves sessile or nearly so, usually 1-1.5 cm long, not collapsing when taken from 



the water 3. R. longirostris. 



Plants terrestrial, growing in springy places and lowland, and on dry, wooded slopes; 

 leaves not finely dissected; achenes not wrinkled. 

 Radical and stem leaves all entire or dentate. 



Radical leaves ovate or oblong; stem leaves linear or lanceolate; blades generally 

 less than 6 cm long and 1 cm wide; annuals. 

 Plants glabrous, erect at first, then trailing; petals 1-5, about 1.5 mm long; 



stamens 3-10; achenes brown, beakless 4. R. pusillus. 



Plants sparingly appressed-pubescent, erect; petals 5, 3-7 mm long; stamens usu- 

 ally 20-25; achenes greenish; beak about 0.2 mm long. . . .5. R. oblorigifolius. 

 Radical and stem leaves lanceolate or the lowest ones oblong, generally all den- 

 ticulate; blades mostly 6-12 cm long and 5-30 mm wide; plants ascending 



and rooting at the lower nodes, glabrous ; perennial 6. R. ambigens. 



Radical and stem leaves not all entire or dentate. 



Achenes less than 1.7 mm wide, without a distinct margin, the style very short, not 



over 0.4 mm long; petals generally very small, shorter or not much longer 



than the sepals. 



Plants glabrous (sometimes a few hairs on the stipular sheaths at the base of 



the leaf) ; annuals. 



Radical leaves mostly crenate, sometimes 3-lobed or 3-parted, conspicuously 



cordate; calyx glabrous; petals shorter than the reflexed calyx; heads 



subglobose; achenes mostly 1.2-1.7 mm wide, the stigmas nearly sessile; 



plants of various habitats, the stems solid 7. R. abortivus. 



Radical leaves all lobed or parted, not conspicuously cordate; calyx pubescent; 

 petals about equaling the calyx; heads cylindric; achenes mostly 0.8-0.9 

 mm wide, the stigmas nearly sessile; plants of springy or very wet places, 



the stems hollow 8. R. sceleratus. 



Plants more or less pubescent. 



Roots not thickened; annuals; plants of springy or very wet places; stems 

 hollow, usually 3-9 dm high; heads of fruit cylindric; achenes many. 



8. R. sceleratus. 



Roots thickened; perennials; plants generally of the crests of wooded ridges 

 or of wooded slopes; stems solid, generally less than 3 dm high; heads 



subglobose; achenes few 9. R. micranthus. 



Achenes more than 1.7 mm wide, with a distinct margin, the style more than 0.4 

 mm long; petals rather large except in nos. 11 and 12 (R. recivrvatus and 

 R. pennsylvanicus) . 



Base of stem swollen, bulbiike; introduced plant 10. R. bulbosus. 



Base of stem not swollen, not bulblike. 



Flowers small; petals generally less than 3 mm long, shorter than or scarcely 

 exceeding the sepals. 

 Stems solid, with a spreading pubescence; none of the radical or stem 

 leaves divided to the base; mature heads globose; mature styles (beaks) 



hooked 11. R. reciirvatus. 



Stems hollow, hispid-pubescent; some or all of the radical leaves and usually 

 some of the stem leaves divided to the base into 3 parts, the parts 

 stalked; mature heads longer than wide; mature styles straight. 

 12. R. pennsylvanicus. 



