MEMOIRS FROM THE DEPARTMENT OF BOTANY OF COLUMBIA UNIVERSITY 53 
with leaves green on the upper surface, but the two forms grade into each other in so 
many ways that it is useless to try to draw a line between them. 
Potentilla concinna divisa Rydberg. 
P. nivea dissecta S. Wats. Proc. Am. Acad. 8: 559, at least in part. 1873. Not P. 
dissecta Pursh, 1814. 
Potentilla concinna divisa Rydberg, Bull. Torr. Bot. Club, 28: 451. 1896. 
ILLUSTRATIONS: PLATE 14, f. 6. 
Leaflets pinnately divided. In a few specimens the leaves are also pinnate rather 
than palmate. 
Dr. Watson included the first three specimens cited below in his P. nivea dissecta, 
but they are much nearer in every respect P. concinna than P. nivea, the sepals, petals 
and general habit being exactly that of the former. 
Rocky Mountains : Douglas. 
Montana: Howard. 
South Dakota: Jenney, 1875; W. H. Forwood, 1887; P. A. Rydberg, Nos. 672 and 
673, 1892. 
Assiniboia: John Macoun, No. 4541, 1894; Nos. 10468 and 10469, 1895. 
Manitoba: Macoun, No. 12628, 1895.* 
26. Potentilla oblanceolata. 
Stems several from the caudex, decumbent or spreading, about 1 dm. long, with few leaves 
silky-villous. Basal leaves numerous, digitately 5-foliolate, silky and green above, densely white- 
tomentose beneath ; leaflets narrowly oblanceolate, serrate with small upwardly directed teeth, 3-5 
cm. long ; stem leaves trifoliolate or simple. Hypanthium silky and white-tomentose ; bractlets nar- 
rowly lanceolate, nearly equalling the similar sepals. Petals yellow, broadly obcordate, exceeding the 
sepals by about one-third. Stipules brown and decurrent, the free portion long, linear-lanceolate. 
It is nearest related to P. concinna, but differs by its narrower sepals and bractlets, its narrowly 
oblanceolate leaflets and their dentition. 
Mexico, S. W. Chihuahua: Dr. E. Palmer. 1885 (type in U.S. Nat. Herb.). 
27. Potentilla bicrenata Rydberg. 
Potentilla bicrenata Rydb. Bull. Torr. Bot. Club, 28: 481. 1896. 
ILLusTRATIONS: PuLaATE 15, f. 1: dissection of flower, f. 2; pistil, f. 3; stamen, f. 4; 
fruiting hypanthium and calyx, f. 5. 
