308 ° BOTANICAL GAZETTE [APRIL 
The most important development of vegetation on the com- 
plex is in the “ blowouts,” or hollows produced by the wind, 
These depressions sometimes reach down almost to the water 
level and may be as much as thirty meters below the general 
level of the complex about them. In these depressions the sand 
is moist and protected from the severest action of the wind, so 
that seeds find ready lodgment and a favorable opportunity for 
germination and growth. The commonest plants observed are 
the annuals and biennials mentioned just above, and the follow- 
lowing perennials : Populus monilifera, Salix longifolia, adenophylla, 
and glaucophylla, Juncus Balticus littoralis. Seedlings of the cot- 
tonwood and the three willows appear by the thousand, anda 
large number survive the rigors of the winter. This is the one 
dune habitat where Juncus and Salix longifolia are at all abun- 
dant. These two species are marvelously well adapted to inaugu- 
rate dune capture. Both of these plants have very extensive 
powers of vegetative propagation. Rootstocks of this last-nantes 
willow often trail along in the sand for ten, twenty, or thirty 
meters. Thus the plants extend their area up the slopes of the 
depression on all sides by means of this vegetative increase 
fig. 18 shows a lee slope on the complex, which has been almost 
entirely captured in this way. The dense clump of narrow 
leaved shrubs at the center is Sa/ix longifolia, probably all — 
from one or two plants that have spread vegetatively. 
broad-leaved shrubs and trees are Populus monilifera. 
THE UNIVERSITY OF CHICAGO. 
[ Zo be concluded. | 
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i 
