74 FORAGE PLANTS AND THEIR CULTURE 



have never been improved by artificial selection. As a 

 general rule, locally grown seed is likely to be most satis- 

 factory, but this is by no means always the case. The 

 reasons for this phenomenon are not clear, but it is com- 

 monly believed that all plants become better adapted to 

 the conditions of culture, or the climate and soil of the 

 region in which they are grown a long time, by the gradual 

 elimination of such individuals as do not thrive. 



In North America the seeds of most forage crops are 

 grown in the same general region in which they are cul- 

 tivated, but the exceptions occur to this in case of alfalfa, 

 vetches and many grasses of minor importance. In 

 Europe, on the contrary, there is a relatively much greater 

 importation of grass and legume seeds from foreign sources, 

 so that much experimentation has been devoted to deter- 

 mining their relative crop-bearing capacities. 



It is usually possible to determine the origin of any lot 

 of forage crop seed by the presence of characteristic weed 

 seeds. Thus, if orchard-grass is found to contain seeds 

 of Lepidium virginicum, Panicum dichotomum or Carex 

 cephalophora, it certainly was grown in North America; 

 if it contains Danthonia pilosa, Danthonia semiannularis, 

 Sporobolus indicus, Hypochceris radicata and others, it in- 

 dicates New Zealand origin. If alfalfa seed contains that 

 of Grindelia squarrosa, it is probably from the western 

 United States ; while Argemone alba indicates an Argen- 

 tine origin, and Centaurea picris that it is from Turkestan. 



67. Seed inspection. In recent times the adulteration 

 and misbranding of seeds is becoming less common, mainly 

 due to legislation and the official examination of seeds at 

 special central stations or laboratories. The first of 

 these was established in 1867 at Tharand, Saxony, by 

 Nobbe. At the present time such stations are supported 



