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: G. A. Geyer (Nicollet's Exped.), No. 361, 1838 (type). 



Mmouri: B. F. Bush, 1890, 1893. 



foira : Hitchcock. 



15. Potentilla rivalis Nutt. 



PotentiUa rivalis Nutt.; Torr. & Gray, Fl. N. Am. 1 : 437. 1840. 



Dietr. Syn. PI. 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, PI. Fend., in Mem. Am. Acad. 4 : 42 ; Torr. Pac. R. R. Rep. 5 : No. 4, 84 ; 

 Gray in Ives' Rep. App. 11 ; Wats. Proc. Am. Acad. 8: 552 ; Porter & Coult. Fl. Colo. 

 36; Brewer & Wats. Bot. Gal. 1 : 178 ; Wats. & Goult. in Gray, Man. PM-. 6 : 159 ; K. 

 Brandegee, Zoe, 2 : 383 ; Rydb. Fl. Neb. 21 : 17 ; Bull. Torr. Bot. Glub, 23 : 260 ; Brit- 

 ton & Brown, 111. Fl. 2 : 213. 



Illustrations : Lehm. Rev. Pot. pL 61. Plate 7, f. 1 ; dissection of flower, /. 2 ; 

 pistil, /. 3 ; fruiting hypanthium and calyx, /. 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 cm. 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. Starnens 

 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, Avhich are ternate. Occasionally, especially in depauperate speci- 

 mens, all the leaves are ternate, Avhen 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 Ghicago. 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 ere- 



