80 WEEDS OF THE FARM AND GARDEN 



European weeds are, however, great pests. Tumble 

 weeds (Cycloloma atriplicifolium and Corispermunt hys- 

 sopifolium) and ragweed (Ambrosia trifida) may be men- 

 tioned among the troublesome weeds of the West. The 

 preponderance of these weeds is possibly due to the new- 

 ness of the country, or it may be because of the plasticity 

 of the plants themselves or on account of certain climatic 

 conditions. In southern Atlantic states there is a sur- 

 prising number of weeds that are of tropical origin. 

 Among these are the spiny amaranth (Amaranthus spino- 

 sus), Mexican tea (Chenopodium ambrosioides), senna 

 (Cassia occidentalis), common morning glory (Ipomoea 

 purpurea) and I. hederacea. Quite a number have come 

 from India, as Jimson weed (Datura Stramonium), helio- 

 trope (Heliotropium indicum), etc. Others are European. 



Turning to the weeds of the Pacific coast, it may be 

 said that its weed flora is entirely different. Dr. Hilgard, 

 in an interesting series of .articles, "The Weeds of Cali- 

 fornia," in Garden and Forest, says : 



"The broad fact in the premises that first strikes the 

 newcomer in California is that a number of plants that 

 are subjects of careful culture east of the Rocky moun- 

 tains, as well as in Europe, and which quickly succumb 

 when deprived of artificial protection there, are here 

 among the most persistent and obnoxious weeds ; while 

 very many of those that are troublesome in the Atlantic 

 region are conspicuously absent on the Pacific side. Rad- 

 ish, beet, celery, carrot, are conspicuous weeds. The 

 smartweeds (Polygonum) are almost entirely absent on 

 the Pacific coast. Amaranths flourish. Pusley, so 

 troublesome in eastern states, has appeared in but few 

 localities. As- yet it has made no headway as a trouble- 

 some weed. Bur clover (Medicago dcnticulata), so 

 troublesome in South America, was one of the earliest of 

 European introductions in California, and is a great 

 pest." These illustrations suffice to show the differences 



