492 MINNESOTA BOTANICAL STUDIES. 



mersed leaves ternately decompound into narrow filiform or 

 capillary divisions, flaccid, petioles very short and sheathing ; 

 emersed leaves smaller, and much less dissected, often only 

 3~7-parted into cuneate lobes, petioles often longer than blades; 

 young leaves from nodes taking root on muddy banks, still less 

 lobed and divided, their petioles and under sides hairy : petals 

 deep yellow, 5 to 8, broadly obovate, 4 to 6 lines long, exceed- 

 ing the sepals : akenes rather turgid, obliquely ovate, hardly i 

 line long, becoming callous-margined on base and ventral edge ; 

 beak half their length, straight, compressed : head of fruit glo- 

 bose or oblong. Quiet water, and muddy ditches and banks. 

 North Carolina to northern Canada, west to British Columbia 

 and California. Also Siberia. 



71. R. Purshii RICHARDS, Frankl. ist Journ. 741. 1823. 

 R. pusillus LEDEB. Mem. Acad. Petrop. 5: 546. 1812. 

 R. Gmclini DC. Syst. 1 : 303. 1818. 



R. Langsdorfii DC. Prod. 1 : 34. 1824. 



R. limosus NUTT. ex Torr. & Gray, Fl. I : 20. 1838. 



R. radicans REGEL, Bull. Soc. Nat. Mosc. 34 : pt. 2 : 

 44-5. 1 86 1. Not Mey. 



R. multifidus var. limosus LAWSON, Rev. Canad. Ranunc. 

 47. 1870. 



R. multifidus var. repens WATS. Bot. King Exp. 8. 1871. 

 Stems slender, rooting at lower nodes and creeping, in muddy 

 places, pubescent on younger parts : leaves slender-petioled, 

 3 to 12 lines broad, palmately divided into obtuse lobes and seg- 

 ments : petals yellow or whitish, i to 3 lines long, ovate ; sepals 

 smaller, falling early : akenes smooth, y 2 line long, no cal- 

 loused margin ; style persistent, slender, shorter than the body : 

 head of fruit smaller than in R. del-phinifolius , Bogs, ditches, 

 etc. Arctic America to Northern Michigan, west to British 

 Columbia and Washington, south to New Mexico. 



72. R. Missouriensis GREENE, Erythea, 3: 20. 1895. 

 Much like R. Purshii in habit and leaves : differs in being 



sparingly pubescent : leaves wider than long, i to 3 inches 

 wide : head of fruit more oblong : akenes prominently callous- 

 margined up one edge, sides wrinkled ; style subulate, y 2 as 

 long as body. Missouri to New Mexico. 



73. R. aconitifolius LINN. Sp. PI. 551. 1753. 



Plant pubescent, y 2 to 3 feet high, branched : leaves pal- 



