42 



THE FERN BULLETIN 



the difficulty seems almost insurmountable since the 

 immense distance enters into the matter. Fern spores 

 are light, however, and capable of remaining in the 

 air a long time. Nevertheless it must have been one 

 chance in many millions that enabled a single spore, 

 after travelling half way around the earth to find the 

 exact combination of soil, moisture, shade, tempera- 

 ture, climate, and elevation to allow it to establish a 

 colony. 



FERNS OF SAN DIEGO COUNTY, CALIFORNIA. 



BY LAURA F. KIMBALL. 



It may interest the readers of the Fern Bulletin to 

 have a short account of the ferns of San Diego County, 

 California, as collected by me. (There are other kinds 

 growing in the eastern part of the county, about 60 

 miles from here, that I have never collected). Our 

 fern season is from February to the middle of May, 

 varied as we have more or less rain. 



There are four stations where we find quite a num- 

 ber of ferns, and a few others grow by the roadside 

 as we go to these places. The stations are "Old Mis- 

 sion Dam," about twenty miles from National City, 

 San Miguel Mountain 12 miles, Otay Canon twelve 

 miles, and Sweetwater Dam seven miles. The ferns 

 found by visiting the four, are as follows : Poly- 

 podium Calif or nicum, Gymno gramme triangularis, 

 Gymno gramme triangularis, var. viscosa, Notholaena 

 Nezvburyi, Adiantum emarginatum, Chilanthes Cali- 

 f arnica, Cheilanthes Clevelandii, Pellaea ornithopus, 

 Pcllaca andromcdaefolia, Dryopteris rigida arguta, 

 Asplenium vcspcrtinum, Selaginella Bigelovii, Sel- 

 agineUa cinerascens. I found Azolla HUculoides. 

 Lam. not far from the base of San Miguel Mountain 



