OS THE CHARACTERISTICS OF THE SOUTH AMERICAN FLORA. 557 



American Indian ' 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 ancestors brought it to this continent. Moreover 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 Plantago 

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

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

 at fault, the aborigines may have known the difference. The cows are 

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

 where the two grow together, cows freely feed upon the undoubtedly 

 native species, and leave the naturalized one untouched. 



It has been maintained that the ruderal and agrestial Old "World 

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

 settled countries in virtue of a strength which they have developed 

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

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

 pertinacious weeds of the Old World which have been given to us may 

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

 belong to campestrine or unwooded regions farther east ; and that, 

 following the movements of pastoral and agricultural people, they may 

 have played somewhat the same part in the once forest-clad Western 

 Europe that they have been playing here. But 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 vegetation. 



The one marked exception 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, Mr. John Ball, has 

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

 America beyond the Rio Colorado, lying between the same parallels of 

 latitude in the South as Montreal and Philadelphia in the North, and 

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

 a fair proportion of forest, ai'e 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 Mr. Darwin long ago inti- 

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

 because the only country from which they could have been derived — 

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

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

 to continue the extract from Mr. 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 

 great mountain range mainly clothed with an alpine flora requiring the 

 protection of snow in winter, 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 newly. formed region were the comparatively 

 few which, though developed under very different 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.' 



