292 BOTANICAL GAZETTE [APRIL 
fig. 13 shows the encroachment of a low dune upon a sedge 
swamp. The beachlike fringe of sand at the base of the dune 
is peculiar to dunes that encroach on swamps. Considerable 
sand rolls or is blown beyond the base of the steep slope. Under 
ordinary conditions this sand is blown away, but as soon as it 
reaches the wet, swampy ground, it becomes moist, and hence 
remains for a time as a fringe to the dune. The plants of a 
sedge swamp are unable to adapt themselves to a dune environ- 
ment, and quickly succumb. Fig. 74 shows a dune advancing on 
a more mesophytic flora and on a group of pines. The effect 
here is also destructive, in the main. An interesting pocket i 
the dune, in which there is a group of pine trees, appears it 
this figure. 
One of the most remarkable phenomena seen in the dune 
region is shown in fig. 75. A dune about twenty five meters 
in height is advancing with considerable rapidity upon a bulrush 
swamp. This swamp is more or less continuously surrounded 
by a marginal fringe of willows and dogwoods. The bulrushes 
are quickly destroyed, but the dogwoods and willows have thus 
far been able to remain not only alive but luxuriant. In ordet 
to keep above the sand, these plants are obliged to lengthen : 
stems far more than is ever the case under normal cone 
Already some of these plants have twice and three times vi 
normal stem height. The buried portions of the stems, ag? 
larly of the willows, send out roots almost as soon as wee 
buried. These plants, therefore, become more and more ! 9g 
pendent of the deeper soil in which they first grew, oe ook 
one of the greatest dangers that was mentioned im ores: 
with many tenants of the embryonic dunes. : dapt them 
Three species have been found that are able to aéap 
selves almost immediately to a dune environment, shrubs 
phylla, S. adenophylla, and Cornus stolonifera’ The tars gai 
Some of the Cornus stolonifera may prove to be C. Baileyi. pace 
certainly intergrade in the dune region. The pubescence peenort iad 
tion of habitat. The best determinative character is the mga © 
nearly all specimens examined, whether from the swamps OF 
C. stolonifera. See Bor. Gaz. 15: 38, 86-88. 1890. 
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