294 RANUNCULACEAE 



Beaks of the achenes minute or none. 



Petals 5-7 mm. long, broadly obovate; stamens many. 



Primary divisions of the leaves 11.5 cm. long, rather rigid, scarcely col- 

 lapsing when withdrawn from the water. 3. B. trichophyllum. 

 Primary divisions of the leaves 1.5-3 cm. long, flaccid, collapsing when 



withdrawn from the water. 4. B. flaccidum. 



Petals less than 5 mm. long, oblong-obovate; stamens 5-12. 

 Stem slender, but not capillary; leaves not very flaccid. 



5. B. Drouetii. 



Stem capillary-filiform ; leaves very flaccid. 6. B. confervoides. 



Upper leaf-blades floating, reniform, merely cleft or toothed, the rest submersed and 

 with capillary divisions. 7. B. Grayanus. 



1. B. Porteri Britton. Stem 1 m. long or more; leaves all submerged; peti- 

 oles 1-2 cm. long, dilated at the base; blade 4-5 cm. broad, repeatedly ternately 

 divided, with narrowly linear, attenuate divisions; petals 3-4 mm. long; achenes 

 6-12 in a head, obliquely oval, nearly 2 mm. long, almost beakless. In water: 

 Henry's Fork, e Ida. 



2. B. longirostre (Godr.) F. Schultz. Stem very leafy and branched; 

 petioles very short; blades 2-4 cm. broad; petals broadly ovate, 5-7 mm. long; 

 head of fruit globose; achenes many, about 1.5 mm. long. Ranunculus circin- 

 alus A. Gray, in part, not Sibth. Ponds and slow streams: Ont. N.Y. N.M. 

 Utah S.D. Plain. Je-Au. 



3. B. trichophyllum (Chaix.) Bosch. Stem 3 dm. long or more; petioles 

 1-1.5 cm. long; blades 2-3 cm. wide, usually with spreading divisions; petals 

 about 8 mm. long; head of achenes globose, 4 mm. thick; achenes many, about 

 1.5 mm. long. Ponds and slow streams: N.S. N.C. Calif. B.C.; Mex.; 

 Eurasia. Plain Mont. Je-S. 



4. B. flaccidum (Pers.) Rupr. Stem long and slender; leaves rather distant; 

 leaf -blades 3-5 cm. broad, with usually ascending segments; petals 5-8 mm. 

 long, white; head of fruit about 4 mm. wide; achenes often nearly 2 mm. long. 

 In streams, rarely in ponds: Lab. N.C. L. Calif. Wash. Plain Mont. 

 My-S. 



5. B. Drouetii (F. Schultz) Nym. Similar in habit to B. trichophyllum, 

 but more slender; leaf-blades 1.5-3 cm. wide; petals 3-5 mm. long; head of 

 achenes about 4 mm. thick, globose; achenes about 1.5 mm. long. In streams: 

 Vt. R.I. N.M. -L. Calif. Alaska; Eurasia and Africa. Plain Submont. 

 Je-S. 



6. B. confervoides Fries. Stem 1-2 dm. long, very slender; leaf-blades 

 2-4 cm. wide; petals about 3 mm. long, oblong; achenes about 1 mm. long. In 

 cold pools and lakes: Man. Colo. Alaska; Eu. Mont. Au. 



7. B. Grayanus (Freyn) Rydb. Stem long and slender; submerged leaves 

 short-petioled, finely dissected into capillary divisions, 3-8 cm. in diameter; float- 

 ing leaves with petioles 2-3 cm. long; blades reniform, 1-3 cm. broad, 3-cleft; 

 middle lobe cuneate, usually 3-lobed; lateral lobes broadly cuneate-obovate, 

 usually twice 2-lobed; petals 5-7 mm. long, obovate; achenes hairy, nearly 2 mm. 

 long. Ranunculus aquatilis A. Gray, not L. R. Grayanus Freyn. In water: 

 Alaska Mont. Calif. Submont. Ap-Jl. 



10. RANUNCULUS (Tourn.) L. CROWFOOT, BUTTERCUP. 



Annual or most all of ours perennial herbs, with a cluster of fleshy-fibrous 

 roots. Leaves alternate, entire, lobed, divided or dissected. Flowers solitary 

 or cymose. Sepals mostly 5, deciduous. Petals 5 or more, in ours yellow, each 

 with a nectariferous pit and a scale at the base of the blade. Pistils several or 

 many, 1-ovuled. Achenes flattened, smooth, papillose, or echinate, tipped with 

 the style, not striate. 



Achenes smooth. 



Leaves linear to oval, entire, or merely denticulate or crenate, none divided or cleft. 



I. FLAMMULAE. 

 Some of the leaves at least cleft. 



Sepals black-hairy. II. NIVALES. 



Sepals not black-hairy. 



Some of the basal leaves entire. 



Basal leaves linear or divided into 3 linear divisions. V. DIGITATI. 



