VOL. i: Naturalized Plants. 207 
country of any particular one does not authorize the presump- 
tion that it is not there indigenous. Positive evidence, either his- 
toric or drawn from the circumstance of its growth, must be pro-— 
duced to justify its removal from that rank. 
_ Indeed most of the species above enumerated have been regarded 
by botanists as natives of this State. A few, however, have been 
selected, with confidence or with doubt, as introductions. They are 
indicated in the list by italic type. 
The possibility of such an introduction is thus cautiously suggest- 
ed by Gray and Hooker: ‘‘ There are a number of plants indigenous 
to Chili, the presence of which in California, where they are seem- 
ingly no less indigenous, may be accounted for by immigration o¢ 
men and cattle. This may have been the case with Pentaczena, 
Acena, Valerianella samolifolia, Bowlesia, Amblyopappus, Pecto- 
carya, Lastarrizea, and the like.’”’* 
I do not know that any others have expressed this doubt respect- 
ing Pentaceena, Aczena, Bowlesia and Valerianella, and the first 
three are included among our native plants by the Botany of Cali- 
fornia, and the last both in that work and in the Synoptical Flora. 
Regarding the others more uncertainty has prevailed. Thus in 
1876 Dr. Gray mentions the Californian Soliva as S. daucifolia Nutt., 
remarking that it is “much like S. sessz/is of Chili,”’} to which spe- 
cies he afterwards reduced it. In 1881 he questions if it be not a 
“North American species immigrated’’ to Chili.f In 1884 he 
makes the contrary note, ‘‘Chili; whence probably introduced”’ 
into California,§ but includes it among the natives in the enumera- 
tion of genera and species. 
The same distinguished botanist regarded Microcala with like 
uncertainty. In 1876 he says that it inhabits ‘‘hillsides and moist 
meadows about San Francisco, Martinez and Vallejo, where it may 
readily have been introduced. But also on the coast, near Mendo-- 
~ cino, so that it may be indigenous.’’§ In 1878 he says that it isa 
native of the ‘‘Coast of California, from Mendocino southward.” || 
 *Veget. Rocky Mts., I. c. : §Syn. FI., 1, ii, 365. 
TBot,. Cal., i, 405, Bot. Cal., i, 480. 
t{Veget. Rocky Mts., 59. Syn. Fl., 2, 1, 122- 
