42 MEMOIRS FROM THE DEPARTMENT OF BOTANY OF COLUMBIA UNIVERSITY 
P. paradoxa. Only the basal leaves have several more or less distant pairs of leaflets ; 
the lower stem leaves have generally two approximate pairs, and the rest are ternate. It 
is a rather rare plant. The following specimens have been examined : 
North Dakota: C. A. Geyer ( Nicollet’s Exped.), No. 361, 1888 (type ). 
Missouri: B. F. Bush, 1890, 1893. 
Towa:  Hiteheock. 
15. Potentilla rivalis Nutt. 
Potentilla rivalis Nutt.; Torr. & Gray, Fl. N. Am. 1: 487. 1840. 
Dietr. Syn. Pl. 3: 178; Walp. Rep. 2: 31; Ann. 2: 515; Lehm. in Otto, Gart. & 
Blumenz. 7: 350: Ind. Sem. Hort. Hamb. 1851: 10; Linnaea, 25: 313; Rev. Pot. 196. 
Gray, Pl. Fend.,in Mem. Am. Acad. 4: 42; Torr. Pac. R. R. Rep. 5: No. 4, 34; 
Gray in Ives’ Rep. App. 11; Wats. Proc. Am. Acad. 8: 552; Porter & Coult. Fl. Colo. 
36: Brewer & Wats. Bot. Cal. 1: 178; Wats. & Coult.in Gray, Man. Ed. 6: 159; K. 
Brandegee, Zoe, 2: 383; Rydb. Fl. Neb. 21: 17; Bull. Torr. Bot. Club, 28: 260; Brit- 
ton & Brown, Ill. Fl. 2: 218. 
InLusrratrons: Lehm. Rey. Pot. pl. 61. Puare 7, f. 1; dissection of flower, f. 2; 
pistil, f. 3; fruiting hypanthium and calyx, f. 4. 
Stem erect and simple, branched above, often tinged with brown or purple, villous- 
hirsute, leafy. Stipules broadly ovate, 1-2 cm. long, often coarsely toothed. Lower 
leaves pinnate with two pairs of approximate leaflets, the upper trifoliolate, sometimes all 
trifoliolate. Leaflets 2-5 em. long, obovate, incised. Cyme leafy, branched, with ascend- 
ing branches. Flower on short pedicels, less than 5 mm. in diameter. Hypanthium 
hirsute in age, about 5 mm. in diameter. Bractlets oblong, obtuse or acute, rather shorter 
than the ovate acute sepals. Petals cuneate, much shorter than the sepals. Stamens 
about 10. Pistils numerous; style terminal, fusiform. Achenes smooth. 
This differs from the preceding by its upright habit, cymose inflorescence, small petals 
which are scarcely half as long as the sepals, and achenes without any swelling on the 
inner side. ‘The leaves are generally pinnate with two pairs of approximate leaflets, ex- 
cept the upper ones, which are ternate. Occasionally, especially in depauperate speci- 
mens, all the leaves are ternate, when it is very difficult to separate it from the next. 
The range is from Oregon and Saskatchewan to Mexico. I have seen a single specimen 
from. the stockyards of Chicago. All specimens named P. rivalis from the prairie States 
that I have seen belong to the following species. 
A form of P. rivalis with a large cluster of basal leaves with rounded, coarsely cre- 
