Jan. 1901.] BOTANICAL SOCIETY OF EDINBUKGH 21 



the shores in remote places would seldom if ever have 

 taken place before the introduction of potatoes. In forming 

 an opinion as to certain doubtful plants being indigenous 

 in any locality or the reverse, it is necessary to know the 

 manner in which the inhabitants carry on their cultivation. 

 On finding a plant such as Galium AjKirine or Polygonum 

 Fersicaria on some remote part of the shore, it is apt to be 

 at once taken as being of the same class of plant as Fcstuca 

 ovina, or any other undoubtedly native species. After an 

 examination for some years of the distribution of the 

 Galium, I have come to the conclusion that it not a native 

 of this coast. It is very common on shingly shores, the 

 locality evidently being most suitable for it, but it is always 

 most plentiful on the shores near houses and waste places, 

 and decreases in proportion to its distance from them. 

 Taking this into consideration, with the fact that it is a 

 common weed of cultivation — and I have evidence of its 

 introduction to an island by this means — I cannot regard 

 it as having the same locus standi in the flora of the district 

 as a plant about which there is no doubt. It will at times 

 be found in remote places on the shore, but comparatively 

 rarely, and stray plants of oats and potatoes can also be 

 found in such places. I have given the Galium as an 

 instance of the care which should be taken in forming an 

 opinion as to plants being indigenous in any locality, as 

 this species seems so much at home on the shingle, and 

 occasionally forms a distinct habit. Many of our species, 

 usually regarded as native, must be placed in the same 

 category as the Galium. They differ from the ordinary 

 native vegetation in that their migration bears distinct 

 marks of an introduction by man's agency, though probably 

 often remote : but they are not colonists in the sense of the 

 word as used by Watson, as they have now found a suitable 

 place of growth independent of agricultural operations. 



The date of the introduction of cornfield weeds must 

 always be a matter of conjecture, as agriculture has been 

 carried on before there were historical records. Some light 

 is thrown on the subject through observations by former 

 writers. We learn that there was no change of seed when 

 sowing bear, rye, and oats — the only crops of the Highlands. 

 This would prevent the introduction of fresh weeds. Some 



