plants "like" their native climate better than the relatively gentle 

 climate of Stanford. There is a difference of four months between 

 the time of flowering of the Big Horn Lake plants at Stanford and 

 their time of flowering at Timberline. The early flowering at 

 Stanford is probably a result of the fact that the plants can de- 

 velop sufficient food reserves during the mild winter to produce 

 flowers in early spring; at TimberHne, the plants require about 

 two months to produce flowers after the snow leaves the ground. 

 Presumably flowering in August is generally early enough to 

 develop seeds before the first killing frost of autumn, although 

 there must be numerous years when seeds do not develop because 

 of early severe freezes. 



The observations of the Carnegie group on Achillea and some 

 other, unrelated plant species that are also widely distributed in 

 California suggest that each of these species is able to occupy a 

 wide range of habitats not because of the great plasticity of a 

 single genetic type, but because each of these species is subdivided 

 into a number of local, climatically adapted, genetically different 

 races. These climatic races are called climatic ecotypes, in the 

 same way that serpentine-tolerant and -intolerant races of Gilia 

 capitata are called edaphic (soil) ecotypes. 



The Carnegie group concluded that in California ^c/2///efl is 

 made up of eleven statistically different climatic ecotypes that 

 occur along the 200-odd mile (322 km) transect running from the 

 Pacific coastline to the eastern boundary of the state. They sug- 

 gested that there are probably hundreds of ecotypes oi Achillea 

 over its entire range in Europe and North America. To para- 

 phrase some of the major conclusions of the Carnegie workers 

 based on their transplant work: 



1 . There is an intricate balance between a plant and its en- 

 vironment. 



2. Species consist of ecotypes, each of which is in equilibrium 

 with its environment. (However, their transplant work indicated 

 that there was a fair amount of variability of response within 

 each population. While the figures given in the table above are 

 averages, they are averages of a range of responses. This variabil- 

 ity suggested to Clausen, Keck, and Hiesey that each of the 



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