242 Sornu: List OF PLANTS COLLECTED ON PIKES PEAK 
Rhodiola integrifolia Raf. and R. polygama (Rydb.) B. & R. 
are separated with difficulty. While the extremes seem to be 
distinct, there are, on this mountain at least, many intermediate 
forms, some dioecious others polygamous, which seem to merge 
the two species into one. Plants that are polygamous one year 
may bear either staminate or pistillate heads alone the next 
season, and polygamous heads were found upon plants which I 
know bore unisexual flowers the year before. 
Rubus strigosus Michx. occurs well above the timber in many 
places. But while it blossoms freely it rarely matures fruit 
on account of the early frosts and the depredations of the birds, 
which no doubt have brought the seeds of the existing plants up 
from below. 
Salix brachycarpa Nutt. is the prevailing willow above the 
timber line, occurring as dwarfed shrubs well up toward the summit. 
COLORADO SPRINGS, COLO. 
