AMERICAN CINQUE-FOILS. 197 



ican naturalists, please verify, or look out for, the corresponding 

 American species. 



On the Alpine summits of the White Mountains, and far to the 

 north again in the Labrador region, there grows abundantly a little 

 matted mountain plant, not recognized by the scientific world at large 

 as a potentilla at all, and known by the name of Sibbaldia procumbens. 

 But you may call the plant whatever you like without altering the 

 undeniable fact that it is in all essentials a dwarfed and depressed 

 mountain potentilla, with the flowers so reduced by chilly conditions 

 that very few stamens or carpels remain, and with the usual dense, 

 spreading, tufty habit common to all Alpine vegetation. It is clearly 

 descended from a high hill-side potentilla not unlike the white P. 

 tridentata of Mount Willard aforesaid (only with yellow flowers), for 

 it has the same type of tre-foil leaves, with each leaflet three-toothed 

 at the end, and the same general aspect and habit. Both plants, I do 

 not doubt, are common descendants of a single antique Arctic ancestor. 

 But little Sibbaldia has grown so very small and degraded in time 

 that its flowers have dwindled away almost to nothing ; the green 

 calyx forms its most conspicuous part ; the pale-yellowish petals are 

 very tiny, and in many cases are entirely wanting. In the States 

 Sibbaldia is confined to the higher summits of the White Mountains ; 

 but in the Scotch Highlands, as in the far north of British America, it 

 often constitutes for miles together the main element of the low and 

 matted mountain greensward. 



Last among your American potentillas I may mention the wild 

 strawberries. Though these at first sight seem somewhat different 

 from the rest of the group, I have not the slightest hesitation in say- 

 ing that to the evolutionary botanist they can not but appear as closely 

 related species of one and the same natural genus. For the straw- 

 berries are only potentillas in which the receptacle of the fruit, instead 

 of remaining hard and dry, swells out into a colored and pulpy mass, 

 attractive to birds, who thus aid in dispersing the tiny "achenes" or 

 nutlets (commonly, and for all practical purposes correctly enough, 

 described as seeds). To us in Europe, the essential identity of the two 

 types is made all the more evident, because we happen to possess a little 

 three-leafleted white potentilla {P. fragariastrum) so exactly like a 

 wild-strawberry vine in foliage and flower that few save botanists or 

 close observers of Nature ever adequately distinguish between them. 

 This white potentilla is, in fact, a strawberry in everything essential 

 except the fruit ; and the succulence of the fruit (or rather receptacle) 

 is after all a matter of comparatively little importance except to the 

 men and birds who eat it. I am fully convinced that if the straw- 

 berry had not been an edible berry it would always have been classed 

 merely as a potentilla, and considered as very closely analogous to the 

 P. fragariastrum or " barren strawberry " of Northern Europe. It 

 is hardly more, indeed, than a mere variety. 



