Crosses (Fig. 48) between these two varieties were successful 17-100% of the
time with var montanum used as the seed parent and 0-100% of the time with var
siskiyouense as the seed parent. In general, pollen stainability was high, ranging
from 7-100% in the former crosses and 67-92% in the latter.
F1 hybrids were vegetatively vigorous, and, as in var idahoense, the only noticeable
intermediate expression was in the basal leaves (Fig. 49). Herbarium specimens
from the edge of the range of var siskiyouense indicate the intermediate nature of
the basal leaves where var montanum has been in breeding contact with var