126 Muhlenbergia, Volume 5 



are not unlike those of our own Great Plains, and it is in that 

 part of our country that this intruder has given the most trouble. 

 While it has now spread quite generally over the whole United 

 States, it has caused much less damage in other sections. 



In carrying it from place to place, and thus establishing 

 new centers of dispersion, the railways, especially by cattle cars, 

 are thought to be the agents, as they are of the introduction of 

 many other weeds. It was thus, very evidently, that the Rus- 

 sian thistle reached California. It first appeared at Lancaster, 

 Los Angeles county, in Antelope Valley, a region presenting 

 ecological conditions not altogether unlike those of Dakota. 

 Although not brought to notice until 1895, when it had already 

 spread to places ten miles distant in two directions, it was be- 

 lieved to have first appeared only four years before (45). While 

 some efforts have been made to repress it, this weed has now 

 become quite generally diffused throughout southern California. 

 It has not, however, here proved so pestiferous a plant as was 

 anticipated from the ill repute it has acquired elsewhere. 



At San Bernardino I first observed it in 1901, in a stubble- 

 field, where it had probably grown from foul seed grain. It is 

 now to be found throughout the cultivated parts of the valley, 

 mostly by roadsides and in waste places, and to some extent in 

 grain fields. Even there it is not seriously injurious, as the 

 grain is mostly cut for hay before the thistle has developed its 

 rigidity. Indeed were it not for this objectionable quality it 

 might serve as a forage plant, as it has a protein content of 17 

 per cent., indicating a good feeding value. 



Some other Weeds 

 In recent years wild radish {Raphanus sativus) has become 

 a very common weed in grain fields, often quite detrimental to 

 the crop. R. Raphanistrum is just making its appearance, and 

 is as yet rare. Dr. Davidson has observed it at Los Angeles (46), 

 and a few plants have recently been seen at San Bernardino. 



\7>) Davidson, Erythea \\\ 1 ,S' S - 1895; Shinn, Univ. Cal. 

 Agr. Ex. Station Bull. 107: mi 3. [895. 

 Kii Bull. S. Cal. Acad. 2: 29. 1903. 



