56 ‘ERYTHEA. 
have not a doubt that these represent species distinct from 
each other and from the eastern original. If it were in the 
genus Hupatorium a half dozen species would be considered 
firmly established upon differences such as these exhibit. 
IMMIGRANT PLANTS IN LOS ANGELES 
COUNTY, CALIFORNIA.—I. 
By AnstRuTHER Davrpson, M. D. 
To the botanical student in Southern California few things 
seem more remarkable than the number of immigrant plants 
that, not only maintain their established footing, but in many 
instances increase their range with a rapidity and certainty 
that precludes the possibility of their extinction under any 
change of circumstances. While some of these have been 
primarily introduced in the interest of the agriculturist, the 
greater number are weeds accidentally imported. 
Careful reference to the Botany of the State Survey, by 
Brewer and Watson, illustrates the great change our flora 
has undergone in the last thirty years in respect to intro- 
duced species. Many then rare are now common, some then 
adventive have since become established. 
A few years ago Mr. Parish of San Bernardino published 
some interesting notes, entitled, “Naturalized Plants of 
Southern California,” but from lack of opportunity this 
county had not been much explored by him, and his list and 
notes as relating thereto are necessarily incomplete. It is 
my intention in these notes to make good the omissions, and, 
while reviewing the whole ground of the immigrant plants 
of Los Angeles County, to endeavor to convey some idea of the 
comparative scarcity of the different species. To further 
this purpose I have discussed those of each family in the 
order of their relative frequency. 
Brassica nigra, Koch, extends all over the county, and 
eee 
Pe hes Se ey i 
