432 GEOGRAPHICAL DISTRIBUTION [CHAP. VI 



Letter 330 winter in the greatest abundance. Perhaps the barberry 

 belongs to a warmer country than north of Europe, and 

 finds itself more at home in our sunny summers. Yet out 

 of New England it seems not to spread at all. 



Manila Cotula.fide Engelmann, is a scattered and rather 

 scarce plant in Germany. Here, from Boston to St. Louis, 

 it covers the roadsides, and is one of our most social plants. 

 But this plant is doubtless a native of a hotter country than 

 North Germany. 



St. John's-wort (jHypericum perforatuni) is an intrusive weed 

 in all hilly pastures, etc., and may fairly be called a social plant. 

 In Germany it is not so found, fide Engelmann. 



Verbascum Thapsus is diffused over all the country, is 

 vastly more common here than in Germany, fide Engelmann. 



I suppose Erodium cicutarium was brought to America 

 with cattle from Spain : it seems to be widely spread over 

 South America out of the Tropics. In Atlantic U.S. it 

 is very scarce and local. But it fills California and the 

 interior of Oregon quite back to the west slope of the 

 Rocky Mountains. Fremont mentions it as the first spring 

 food for his cattle when he reached the western side of 

 the Rocky Mountains. And hardly anybody will believe 

 me when I declare it an introduced plant. I daresay it is 

 equally abundant in Spain. I doubt if it is more so. 



Engelmann and I have been noting the species truly 

 indigenous here which, becoming ruderal or campestral, are 

 increasing in the number of individuals instead of diminishing 

 as the country becomes more settled and forests removed. 

 The list of our wild plants which have become true weeds 

 is larger than I had supposed, and these have probably 

 all of them increased their geographical range at least, 

 have multiplied in numbers in the Northern States since 

 settlements. 



Some time ago I sent a copy of the first part of my 

 little essay on the statistics J of our Northern States plants 

 to Triibner & Co., 12, Paternoster Row, to be thence posted 

 to you. It may have been delayed or failed, so I post 

 another from here. 



This is only a beginning. Range of species in latitude 



1 " Statistics of the Flora of the Northern U.S." (Sillimaris Journal , 

 XXII. and XXIII.). 



