llii- )<<'>>''l^'ii!^ •"'<1 'lii^ oicliarils, lloiirisli the cosiiKipulitan wctils wliiili loiislil iiU- so 

 large a i>art ol tlu- foreign plant i-opulatioii. Tlu-sc <lt|)ttul upon tin- advani.igcs 

 tlu-y i-njo.v from cultivation and irrigation, and without tluni would disappear; a 

 result wliK-ii may he seen in ahandoiied lields. But the other immigrants which 

 arc ahle to dispense with these aids, anil to compete successfully with the natives 

 uniler tlie unnuulilieil conditions ol nature, have won trom them iiiucli ot tlii' land. 

 It can hardly be thought that the hunch-grasses ami the delicate herbs which once 

 occupied it could ever reclaim it trom the wild-oats and the aggressive bromes 

 now in possession. It would, indeed, remain grass-land, but the primal species 

 could never regain their dominance. 



It may be of interest to note the conduct of these immigrants in their new 

 homes. Some advance slowly, step by step, but persistently; others, once intro- 

 duced, spread with the rapidity oi an epioemic; a few having attained a limited 

 local foothold, do not overpass its bounds. These ditTerences are not entirely de- 

 pendent upon varying facilities for dissemination, important as these are. The 

 effect on distribution of the more strongly marked climates has been already con- 

 sidered; but the aliens share with the natives in their subjection to minor cli- 

 matic and edaphic variations. Some plants of either class abound under the 

 cooler and damper conditions near the seacoast, and one by one disappear as the 

 aridity increases towards the interior. Is'ot always are the limiting causes easily 

 recognized, but it is evident that the ]dant which demands the least delicate 

 adjustment to environment has the best chance for wide difTusion. Vet it can- 

 not be predicted, from the character borne by a weed elsewhere, what future may 

 await its introduction here. Some which have overrun the Atlantic states have 

 liere proven failures. The wild carrot has more than once obtained a foothold, 

 but has not retained it; forty years ago I knew Datura Tatula as an infrequent 

 weed in my neighborhood, and infrequent it still remains. 



EXPLANATIONS 

 Plants in economic or ornamental cultivation and rarely found as temi)orary 

 escapes, arc not included in the following catalogue; nor are those indigenous 

 plants which are among our common weeds of cultivation. General statements as 

 to distribution apply only to the crsmontane region, occurrence in the deserts or 

 mountains being specially noted. Stations are reported, except for the commoner 

 species, and as far as possible chronological data are supplied: in these notes 

 the writer's name as authority is omitted, unless ambiguity might ensue. Notes 

 on distribution in other parts of the state are based on an examination of speci- 

 mens in the herbarium of the State University, and on published records. The 

 bibliograiihy includes all the papers or notices I have been able to find which 

 relate exclusively to the weed flora of the state. In conclusion, I desire grate- 

 fully to acknowledge the assistance I have received, in relation to the plants 

 of their respective regions by notes and specimens kindly communicated by Dr. 

 A. Davidson, of Los Angeles, Mr. I. M. Johnston, of Upland, and Mr. 1". M. Reed, 

 of Riverside. 



SUMMARY 



The number of species and varieties enumerated in the subjoined catalogue 

 is 281; they may be segregated as follows: Naturalized and generally distributed 

 76, naturalized but common only in certain localities 55, naturalized, but no- 

 where abundant 55, adventives, fugitives and waifs 95. The genera are 177; 

 Bromus has 12 species, no other as many as ten. There are 41 families; the 

 Gramineae, with 69 species or varieties, the Compositae, with 49, the Cruciferae, 

 with 21, the Leguminosae, with 16, the Polygonaceae, with 13, and the Caryophyl- 

 laceae and Solanaceae, with 11 each, are the only Families having as many as 

 ten. 



BIBLIOGRAPHY OF THE CALIFORNIA IMMIGRANT FLORA 



Brandegee, K. 



\'erbascum in California. Zoe 5:138. 1901. 

 Davidson, A. 



Immigrant Plants of Los Angeles County. Erythea 1:56-61; 98-104. 1893. 



Immigrant Plants in Los Angeles County. W. Am. Scientist. 4:66-68. 1895. 



The Changes in Our Weeds. Bull. S. Acad. Sci. 9:11, 12. 1910. 



Another Mustard Pest. Bull. S. Cal. Acad. Sci. 12:11. 1913. 

 Davy, T. B. 



Contribution to the History of Achyrodes aureum. Erythea 2:113-119. 1894. 



Solanum eleagnifolium in California. Erythea 4:125. 1896. 



Mentha pulegium. Erythea 4:145. 1896. 



Recent Introiluctions into California. Erythea 4:176, 177. 1896. 



Centaurea solstitialis in Colusa County. Erythea 5:129. 1897. 



Introduced Plants in Calaveras County. Erythea 6:17, 18. 1898. 

 Dewey, L. H. 



The Genus Avena on the Pacific Coast. Erythea 3:29. 1895. 

 Dyer, H. P. 



Some Berkeley Weed Seeds. Rept. Agric. Exp. Sta. Univ. Cal. 1890, 252-266. 1891. 

 Eastwood, A. 



Pelargonium anceps Ait. Erythea 4:34. 1896. 



New Localities for tw'o Introduced Plants. Erythea 4:35. 1896. 



New Station for two Introduced Plants. Erythea 4:99. 1896. 



