10 



The loruicntillac are.a small group, characterized by the more or 

 less spreading, prostrate or creeping stem and long-pedicelled, ax- 

 illary flowers. The original Tormentillae have 4-merous flowers, 

 but sometimes, however, they are 5-merous, and other species that 

 have regularly 5-merous flowers have no other character which 

 would warrant the division into two groups, much less into two 

 genera. The group is mainly European, only one species being 

 a native of North America, viz.: 



POTENTILLA CANADENSIS L. Sp. PI. 498. I 75 3- 



It is a very variable plant, and several species have been pro- 

 posed. What I take as the original P. Canadensis is a. less luxu- 

 riant form of what has generally been known as P. Canadensis sim- 

 plex (Michx.) T. & G. [P. simplex Michx.), not that small, simple, 

 more hairy form, only a few inches high, that grows in poor dry soil, 

 which is 



POTENTILLA CANADENSIS PUMILA (Poir.) T. & G. Fl. N. Am. I : 



443. 1840. 



Potentilla pumila Poir. in Lam. Enc. Meth. 5 : 594. 1804. 



P. Canadensis is common from Maine and North Carolina to 

 Indian Territory and Minnesota. I have seen one specimen col- 

 lected in Nevada, but this was undoubtedly introduced. The variety 

 has about the same range, but is rarer. 



Potentilla reptans L. Sp. PI. 499. 1753. 



This European species has been collected by Martindale in 

 1876 on ballast in New Jersey. It differs from P. Canadensis in 

 the creeping and rooting stem, smaller leaves and large, ovate or 

 elliptical bractlets, which exceed the sepals. 



Potentilla nemoralis Nestler, Mon. Pot. 28 and 65. 18 16. 



Tonnentilla reptans L. Sp. PI. 500. 1753. Not Potc.Jilla 

 reptans L. 



Also a European species which has been collected in Labrador. 

 It differs from P. Canadensis in the 4-merous flowers and in the 

 leaves, which are all, except the basal ones, ternate. 



Haematochri. The dark purple- or dark red-flowered species 

 of Potentilla constitute a very natural group, which consist of the 



