24 TRANSACTIONS AND PROCEEDINGS OF THE [Sess. lxv. 



Eumex dbtusifolius, Senecio Jaeobcea, Ranunculus repens, 

 Stachys 2^cdustris, 8. sylvatica, Veronica arvensis, Cerastium 

 trivicde, G. glomeratum, Stellaria media, Sagina procumhens, 

 Prunella vulgaris, Polygonum Persicaria, P. Hydropiper, 

 and Poa annua. Cerastium triviale is a very common weed 

 of cultivation, unfrequent far from it. It is also found on 

 hill pastures, where it may be native ; but it can be traced 

 up the hills in its following cattle and sheep, and I think 

 it is probably an addition to the flora of the hills of the 

 coast since the introduction of sheep, C. glomeratum is an 

 agricultural weed, with a tendency to spread from waste 

 heaps along roadsides. Sagina p^vcumhens and Poa annua 

 are of a similar class to Cerastium triviale, probably long 

 established near man and animals, but with their distribu- 

 tion increased since the introduction of a greatly increased 

 number of animals, viz. south country sheep, at the end of 

 the eighteenth century. These two species can be traced 

 by following the footsteps of cattle and sheep, as also can 

 Senecio Jacohcea. In autumn, when cattle are feeding on a 

 pasture where there is much Senecio, their necks can be 

 seen to be covered with the seeds, the pappus being con- 

 spicuous ; the seeds are thus carried for a considerable 

 distance, as I have personally observed. The abundance 

 of >S'. Jacolcca is in proportion to its nearness to houses. When 

 the ground has been left undisturbed for many years, as in 

 deserted crofters' holdings, this plant is comparatively rarely 

 seen, being only able to retain its hold in localities where 

 there is little competition, as on rock ledges and seacliffs. 

 The frequency of alien plants occurring on seacliffs is due 

 to the many bare spots left by weathering, which form 

 suitable ground for the species continuing its existence 

 through seeding in fresh spots before being killed through 

 competition with the native vegetation. Pr2incllct vulgaris 

 prefers ground enriched by manure of animals, and although 

 it is doubtless an old inhabitant of the low ground, its 

 occurrence usually in places on the hills affected by sheep 

 show that it must have increased its range with their 

 introduction. The occurrence of Polygonum Persicaria 

 and P. avicidare in remote places on the shore probably 

 has taken place since the introduction of potatoes, as they 

 are particularly weeds of damp potato ground cultivated in 



