58 Naturalized Plants. [ 



is not especially rare, and it is to be found on the west side of Point 



Loma and at other places about the city. Two other sow-thistles, 



vS". asper^nA S.oleracea are universally prevalent weeds in cultivated 

 ground. 



Coiida australis is found in the south only at San Diego, although 

 not uncommon at the north, whence it has probably reached us. 

 Mr. Cleveland has collected it sparingly in city yards. Its congener, 

 C. coronopifolia is common everywhere, its abundant yellow discs 

 brightening the margins of brooks and ponds. 



Another common northern weed which is known here only at San 

 Diego is the objectionable Centmtrea solstitialis . It is reported as 

 quite common, and is probably destined to become as universally 

 diffused as its ally, C. Melitensis. . - . 



Of the Xanthiums, X. Cajiadetise is a common pest, especially of 

 pastures and the borders of highways. X. spinosum, the Spanish 

 Needle, is as yet fortunately rather rare, but is to be seen here and 

 there by the roadside and is slowly increasing. This may also be 

 said of the handsome but most pernicious Milk Thistle, Silybum 

 Mariamun, so common on the San Francisco sand-hills. Ten years 

 ago I first noticed a half-dozen of these thistles by the Southern 

 Pacific Railway in the San Mateo canon. Their introduction was 

 doubdess due to the railroad. A few years later a single plant ap- 

 peared near Kehls Mills, a mile south of the town of San Bernardino. 

 The mottled foliage of the unknown waif found favor in the eyes of 

 the owner of the adjoining land, who carefully protected it from ac- 

 cidental destruction " to see what it would come to." It came in a 

 few years to occupy the most of the road, and its early protector has 

 paid for his mistaken charity by assiduous but only partially suc- 

 cessful efforts to eradicate it. It is as yet by no means common, but 



It IS to be seen every year in new places and evidently has a future 

 before it, 



^ A thistle of still more recent introduction is Cnicus cdulis, whose 

 indigenous range extends from British Columbia to the bay of San 

 Francisco, but which first appeared here in 1884. In that year a 

 single plant was observed on Arrowhead Avenue, near San Ber- 



s^frn^^r, ^^^.^^'^qf ^ ^°^"^on along this road for nearly a mile 

 south of the original plant. None are to be found north of it a cir- 

 cumstance due to the prevailing direction of the winds during its 

 fmi mg season It is one of the least obnoxious of thistles, and is 

 readily eaten by horses and cattle. 



