48 MEMOIRS FROM THE DEPARTMENT OF BOTANY OF COLUMBIA UNIVERSITY 



Rydberg, Cent. U. S. Nat. Herb. 3: 157; Bull. Torr. Bot. Club, 23: 262; Fl. Neb. 

 21 : 17; Britton & Brown, 111. Fl. 2: 212. 



PotentiUa rivalis var. pentandra Wats. Proc. Am. Acad. 8: 553. 1873. 



Wats. & Coult. in Gray, Man. Ed. 6: 159. 



Illustrations: Lehm. Rev. Pot. pi. 62, f. 4; Britton & Brown, 111. Fl. 2: /. 1923. 

 Plate 11, f. 1; dissection of flower,/. -2; pistil,/. 3; stamen,/ i; fruiting hypanthium 

 and calyx, / 5. 



Stems stout, very leafy, 3-7 dm. high, erect, often tinged with brown, finely hirsute 

 and much branched above. Stipules broadly ovate-acuminate, 1-2 cm. long, deeply 

 toothed. Lower leaves pedately 5-foliolate, or 3-foliolate with the lateral leaflets 2-cleft, 

 with hirsute petioles 3-8 cm. long ; the uppermost 3-foliolate and very short-petioled. Leaf- 

 lets 2-10 cm. long, oblong to oblanceolate or cuneate, deeply serrate. Cyme very dense 

 and leafy, in age, as a rule, flat-topped. Flowers on short hirsute pedicels, less than 5 

 mm. in diameter. Cup sparingly hirsute and finely pubescent, in age about 5 mm. in 

 diameter. Bractlets oblong, acute, nearly as long as the ovate acute sepals but much 

 narrower. Petals pale yellow, oljovate, scarcely half as long as the sepals. Stamens 

 seldom more than 5, very small, with didymous anthers. Pistils exceedingly numerous; 

 style terminal, short-fusiform and glandular below. Achenes smooth, brownish. 



P. pentandra is characterized by its leaves, which are pedately 5-foliolate or 3-foliolate 

 with the lateral leaflets cleft to near the base, by the exceedingly numerous small flowers 

 in a somewhat flat-topped cyme, by remarkably small petals and generally only five 

 stamens. It is often as stout as P. Monspeliensis and more bush}'. Its range is from 

 ^Missouri and Iowa to Alberta and Arkansas. Specimens studied : 



Mis.^ouri: G. Engelmann, No. 970, 1835 (type); B. F. Bush, 1893, No. 280, 1895. 



loipa: Hitchcock; J. C. xVrthur, 1874. 



Nebraska: H. J. Webber, 1888; P. A. Rydberg, No. 1819, 1893; Fred. Clements, 

 No. 2655, 1893; C. E. Bessey, 1890. 



North Dakota: E. L. Greene, 1890. 



Minnesota: C. A. Ballard, No. 252. 



Manitoba: Macoun, No. 12580, 1896. 



Alberta: Macoun, No. 626, 1885. 



