MEMOIRS FROM THE DEPARTMENT OF BOTANY OF COLUMBIA UNIVERSITY 119 



Hemsley, Biol. Cent. Am. 1 : 375 ; Don, Gard. Diet. 2 : 559 ; Dietr. Syn. PI. 3 : 89 ; Walp. Ann. 2 : 

 472. 



Potentilla lineariloba Ser. in DC. Proclr. 2 : 582. 1825. 



Lehm. Rev. Pot. 31 ; Don, Gard. Diet. 2 : 560 ; Dietr. Syn. PI. 3 : 189 ; Walp. Ann. 2 : 472. 



Potentilla candicam nana Humb. & Bonpl. ; Nestler, Mon. Pot. 34. 1816. 



Ser. in DC. Prodr. 2 : 582 ; Lehm. Mon. 67 ; Rev. Pot. 31 ; Don, Gard. Diet. 2 : 559 ; Walp. 

 Ann. 2 : 472. 



Potentilla Humboltiana Tratt. Ros. Mon. 4 : 41. 



Perennial from a thick ligneous root and short caudex ; stem from .5 to 3 dm. high with few re- 

 duced leaves, more or less white-silky. Basal leaves numerous, silvery-white, pinnate, with 6-10 pairs 

 of deeply dissected leaflets ; segments narrowly linear and more or less revolute. Bractlets oblong, 

 about half as long as the ovate or broadly lanceolate sepals. Petals yellow, broadly obcordate, a little 

 exceeding the sepals. Style filiform. 



The variety nana is only a depauperate form. The plant grows in mountain meadows of Central 

 Mexico. 



State of Mexico : C. G. Pringle, ISTo. 2923, 1889 ; No. 4176, 1896 ; F. Miiller, ISTo. 617, 1853 ; 

 *Humboldt & Bonpl an d ; *Coulter, No. 69; *Galeotti, No. 563; Schiede ; E. W. Nelson, No. J 97, 

 1894. 



Potentilla candicans crocea Lehm. 



Potentilla candicans crocea Lehm. Rev. Pot. 32. 1868. 



Flowers orange. 



Mexico: Scheide, No. 585. 



2. HORKELIA Cham. & Schlecht. 



Horkelia Cham. & Schlecht. Linnaea, 2 : 26. 1827. 



Sibbaldia Sprengel, Syst. 4 : part 2, 341. In part. ' 1827. 



Ivesia Torr. & Gray, Pac. R. R. Rep. 6 : 72. 1857. 



Hypanthium deeply campanulate to saucer-shaped. Bractlets, sepals and petals 5. 

 Petals of variable form, strap-shaped, oblanceolate, obovate, cuneate or obcordate, often 

 unguiculate, white or light yellow. Stamens 5-20, inserted in the throat of the hypan- 

 thium and therefore separated from the receptacle by a wide open space ; filaments in 

 EuhorJcelia and Horkeliella dilated and petaloid, persistent, triangular or lanceolate with 

 a distinct midrib, in Ivesia filiform. Receptacle in the first two subgenera generally 

 conic or hemispheric with numerous pistils, in the last mostly small or obsolete with 

 3-15 pistils surrounded by a ring of prominent bristles. Styles long and slender, 

 almost fihform, but generally slightly thickened and somewhat glandular below, articu- 



