Most of the weedy plant species in California, however, are 

 not derived from native species but have been introduced from 

 elsewhere. About seventy-five percent of the weeds of California 

 are of European and western Asian origin, which is not surprising 

 since these regions have been cultivated and inhabitated for very 

 long periods of time and have offered the proper habitats for the 

 origin of weeds for centuries. About 10 percent of the weeds of 

 California are of South American origin, and the remainder form 

 a miscellany from elsewhere in the world. The Gramineae and 

 Compositae together are responsible for about forty percent of 

 the weed species in the state. 



126 



