The west slope of Basin and Castle peaks and the ridge between them displays a wind-generated tree line below 8500 ft, with dry alpine fell-field vegetation above. The butterfly fauna, although depauperate compared to that of the High Sierra farther south, includes some truly boreal elements such as Oeneis ivallda, Plebeius shasta, and Hesperia nevada. These species commonly occur 1500 to 4000 ft higher in the southern Sierra.
Shapiro, Arthur M.
"The alpine butterflies of Castle Peak, Nevada County, California,"
Great Basin Naturalist: Vol. 37
, Article 4.
Available at: http://scholarsarchive.byu.edu/gbn/vol37/iss4/4