AMERICAN CINQUE-FOILS, 193 



own {Tormentilla reptans of the hair-splitters), which sometimes 

 creeps like the true cinque-foil, and frequently breaks out into five- 

 petaled blossoms. Even Mr. Bentham, that minute and conservative 

 botanist, admits that "intermediate forms" sometimes occur which 

 can not probably be referred to either species. 



And yet, though the tormentil and the cinque-foil are thus inti- 

 mately connected with one another, by imperceptible gradations, so 

 great is the love of petty distinctions in the human breast, that Lin- 

 nasus actually erected this slight, four-petaled variety, not only into a 

 distinct species, but even into a separate genus {Tormentilla). 



Let us return, however, to our immediate subject, the American 

 potentillas. The next species recognized by Asa Gray is the silvery 

 cinque-foil (P. argented)^ a pretty little plant, wdth small, bright-yel- 

 low flowers, confined, for the most part, to very dry, barren, or sandy 

 spots, and with thin, wiry, almost woody stems. It is remarkable for 

 the soft, white, silvery down, that clothes the under side of the five- 

 leaved foliage. The use of this down I do not know, though I suspect 

 it to be a protection from some caterpillar or other insect, which at- 

 tacks leaves on their under surface. At any rate, it is an exaggera- 

 tion of the usual downiness of dry-soil species. The silvery cinque-foil 

 is common to Europe and America, and I do not notice any percepti- 

 ble difference between my English and Canadian specimens. It seems, 

 in fact, to be one of the very few plants which have not altered to any 

 recognizable degree on either side of the Atlantic since the end of the 

 great Glacial epoch. As a proof, however, of the narrow way in which 

 this dry-soil species is restricted and limited to the very sandiest or 

 most barren situations, I may mention that it grows on two spots, and 

 two spots only, within reach of my own home here in Surrey, England. 

 Both these spots are knolls of a peculiarly soft and friable sandstone, 

 into which the rain sinks immediately ; and they are the only two bits 

 of that particular formation (a subdivision of the Folkestone sands) to 

 be found anywhere in the neighborhood. 



I was shown, at Kingston, Canada, a specimen of another more 

 weedy potentilla {P. paradoxa), which has hardly, as yet, made good its 

 place in the Eastern States, but which, nevertheless, possesses a certain 

 interest for naturalists of the Atlantic shore, as a member of the flora 

 by which before long they are almost sure to be overrun. The species 

 belongs to the western half of the continent, but it is already well 

 established as an immigrant along the banks of the Ohio and the Mis- 

 sissippi, and it has been observed near Oneida, and elsewhere on the 

 shores of Lake Ontario. My own specimen was gathered on a com- 

 mon at Kingston, where it seemed to have established itself in full 

 vigor. Now the interest of this species centers in the fact that until 

 lately the weeds of the Eastern States and Canada were almost en- 

 tirely of European origin ; they were the cosmopolitan pests of civ- 

 ilization, which have followed agriculture from Western Asia along 



VOL. XXXII. — 13 



