314 PLANT LIFE. 



Thistles, and Senecio jacobaea. If allowed to flourish 

 unchecked, Brambles and Raspberries soon form a sort 

 of thicket ; and eventually Hawthorns, Eoses, and 

 Birch, or Ash may begin to try and form a wood. 

 The flora to be observed by hedges and roadsides 

 is well worth study in this connection, and shows 

 the same tendency though it varies with the ex- 

 posure or soil, and is unfortunately continually 

 disturbed by the roadman. 



In some parts of the country, generally at a higher 

 elevation and in more windy places, thickets of Sloe 

 and Rowan replace Bramble and Hawthorn. On the 

 chalk Downs and in less favoured situations, Leguminosae 

 may replace the Rosaceae as in the case of the Whin or 

 Gorse thickets of England, and of the patches of Broom 

 in the Scottish Lowlands. These may be the final 

 effort of nature in places which are incapable of bearing 

 forest until the Broom and Whin have thoroughly 

 enriched the soil ; but they may be equivalent to the 

 Bramble and Raspberry bushes, which occur wherever 

 good land is allowed to revert to its original state. 



If such a woodland marches with different sorts of 

 vegetation, then the intermediate or bordering plants 

 are appropriate to the special conditions. Thus, in 

 Nithsdale, where woods often cover the whole course of 

 a tributary stream, they will be bordered along the 

 riverside by Alders, and occasionally Saughs or Willows ; 

 where it passes through good arable land, Roses, 

 Brambles, and Hawthorn will occur. At a higher 

 altitude. Bracken may cover the hill pasture, where 

 also the Rowan is common. If the wood happens to 

 be near a peat-moss, Sweet Gale, various Salices (not 

 those of the riverside), and Birch may be found ; and, 

 finally, at a higher altitude, where the wood tails out, so 



