13 



decidedly lenticular, while in P. Anserina the upper end is thicker 

 and rounded-triangular in cross-section. 



P. Egedii is an arctic species, found from Greenland to Alaska^ 

 and extending southward on the coasts to Maine and Oregon. 



The Fniticosae differ from the other groups of North American 

 Potentillac in the following respects : The style is lateral, ovule 

 ascending, achene hairy and the plant more or less shrubby. The 

 American species are : 



POTENTILLA FRUTICOSA L. Sp. PI. 495. 1753. 



This is a native of the north temperate zone, extending in 

 America from Labrador to Alaska south to New Jersey and Colo- 

 rado. In mountain regions the leaflets are narrower with revolute 

 margins, and this form represents P. floribiinda Pursh, P. fniti- 

 cosa temdfolia Lehm. The extreme is reached by the form col- 

 lected by Watson during the King's expedition and described as 

 P. fmticosa parvifolia Wats. It has nearly linear leaflets and 

 smaller long-pedicelled flowers. 



PoTENTiLLA TRiDENTATA Soland. ; Ait. Hort. Kew. 2: 216. 1789. 



P. retiisa Retz. is generally cited as a synonym of P. tridentata 

 and is much older, but P. retnsa is described as having yellow flow- 

 ers, and in the figure of it in Flora Danica the petals are also yel- 

 low, while in P. tridentata, as is well known, they are white. If 

 made from a specimen of P. tridentata it is, indeed, a very poor 

 one, as it resembles Sibbaldia procumbens more than P. tridentata. 

 It can, however, not represent that species, as the petals exceed 

 the sepals. What P. retusa was, or is, is still a secret. 



P. tridentata extends from Greenland to the mountains of North 

 Carolina and westward to Minnesota. 



Biflorac. This contains only one species, placed by Lehmann 

 with P. fmticosa, P. tridentata and their allies. The style is, how- 

 ever, nearly terminal, and the achenes not hairy. It resembles the 

 Fniticosae in the thickish leaves, whose margins are entire, and the 

 non-emarginate petals. The receptacle has also very long hairs. 



PoTENTiLLA BiFLORA WiUd. ; Schlecht. Mag. Gesel. Nat. Fr. 



Berlin, 7: 297. 181 3. 

 It is a native of northeastern Asia, Alaska and the arctic coast 

 of North America, but a rather rare plant. 



