ON Tin; ( UARACTKIUSTICS OF THE NOUIH AMKItU'AN FJ.OilA. 



5.57 



laiiged 

 vacancy 

 iCurope, 

 d in the 

 always 

 ittingly 

 vhilc au 

 slieltered 

 h them, 

 over the 

 lit them, 

 aspect to 

 t" habita- 

 district 

 oed with 

 blue of 

 lis and at 

 common 

 The tall 

 ew clear- 

 d thistle, 

 veritable 



i by the 



American Iiuliaii ' White-Man's foot,' from its springing up wherever 

 that foot had been planted. But there is some reason for suspecting that 

 the Indian's ancn'stors brought it to this continent, !^^oreovor there is 

 another reason for surmising that this long-accepted tradition is factitious. 

 For there was already in the country a native plantain, so like Flantago 

 iuttjur that the botanists have only of late distinguished it. (I acknow- 

 ledfc my share in the oversight.) Possibly, although the botanists were 

 at fault, the aborigines may have known the difTerenco. The cows ai'c 

 said to know it. For a brother botanist of long experience tells me that, 

 wlici'c tlie two grow together, cows freely feed upon the undoubtedly 

 native species, and leave tlio naturalized one untouched. 



It has been maintained that the rudei-al and agrostial Old World 

 plants and weeds of cultivation displace the indigenous ones of newdy- 

 settled countries in virtue of a strength which they have developed 

 through survival in the struggle of figes, under the severe competition 

 incident to their former migrations. And it does seem that most of the 

 pertinacious ■weeds of the Old World -svhich have been given to us may 

 not be indigenous even to Europe, at least to Western Europe, but 

 belong to campcstrine or unwoodod regions farther cast ; and that, 

 following the movements of pastoral and agricultural people, they may 

 have played somewhat the same i)art in the once forest-clad Western 

 Europe that they have been playing here. I>ut it is unnecessary to build 

 much upon the possibly fallacious idea of increased strength gained by- 

 competition. Opportunity may count for more than exceptional vigour ; 

 and the cases in which foreign plants have shown such superiority are 

 mainly those in which a forest-destroying people have brought upon 

 newly-bared soil the seeds of an open-ground v(-getatiou. 



The one marked exce{)tion that I know of, the case of recent and 

 abundant influx of this class of Old World plants into a naturally treeless 

 region, supports the same conclusion. Our associate, ]\Ir. John Ball, has 

 recently called attention to it. The pampas of south-eastern South 

 America beyonci the Hio Colorado, lying between tlie same parallels of 

 latitude in the South as Montreal and Philadelj)hia in the North, and 

 with climate and probably soils lit to sustain a varied vegetation, and even 

 a fair proportion of forest, are not only treeless, but excessively poor in 

 their herbaceous flora. The district has had no trees since its com- 

 paratively recent elevation from the sea. As ]\lr. Darwin long ago inti- 

 mated : ' Trees are absent not because they cannot grow and thrive, btit 

 bocauso the only country from whi(;h they could have been derived — 

 tropical and sub-tropical South America— could not supply species to suit 

 tlic soil and climate.' And as to the herbaoeous and fruitescent species, 

 to continue the extract from ^Ir. Ball's instructive paper recently pub- 

 lished in the Linnean Society's Journal, ' in a district raised from the 

 sea during the latest geological period, and bounded on the west by a 

 groat mountain range maiidy clothed with an al[)ine flora requiring the 

 protection of snow in Avinter, and on the north by a warm-temperate 

 region whose flora is mainly of modified sub-tropical origin — the only 

 plants that could occupy the newdy. formed region were the comparatively 

 few which, though developed under very difl'erent conditions, were suffi- 

 ciently tolerant of change to adapt themselves to the new environment. 

 The flora is poor, not because the land cannot support a richer one, but 

 because the only regions from which a large population could be derived 

 are inhabited by races unfit for emigration.' 



