Sunshine, Rain, and Wind 



the identical climate which their ancestors have endured 

 for many generations.^^ But the environment may 

 change altogether even in the same place. When, for 

 instance, an open rough hillside is planted with young 

 spruces, the conditions are entirely altered as soon as 

 the trees become tall and bushy enough to overshade 

 the ground. At first there may have been an abundance 

 of grasses, quantities of red campions, foxgloves, blue 

 bugles, brambles, and raspberry bushes, and in the more 

 open places the dog violet (Viola canina). 



As soon as the young trees begin to close in over the 

 soil, many of these plants vanish. The brambles and 

 roses will try to become climbers, straggling over the 

 branches. The campions and other herbaceous plants 

 will not flower but produce runners or tubers of some 

 kind. Dr. Krasan declares that under these conditions 

 Viola canina becomes Viola Riviniana,but it is dangerous 

 to agree with him, for most British botanists would 

 emphatically protest. 



Such a thoroughgoing change as this affects every 

 plant in the wood and even the young spruces them- 

 selves. Many plants of the ground flora vanish or 

 retreat into underground reserve stores. Of those that 

 remain, none can be unaffected either in external form 

 or in internal structure.^^ 



Even in one and the same valley there may be lime- 

 stone outcrops or other special and peculiar soils. In 

 that case one may discover closely allied species in- 

 habiting the same valley, but keeping strictly to their 

 own territory. Soldanella minima, for instance, occurs 

 on chalk in central Europe, and S. pusilla replaces it 

 on other rocks. Such replacing species are supposed 

 to be parallel forms derived from some common type. 

 (The usual German term for such species is vicariirender, 

 which might be best translated as curate species, for the 



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