1899] DUNE FLORAS OF LAKE MICHIGAN 289 
the entire coast, though their best development is in associa- 
tion with an extensive dune-complex, as at Dune Park or Glen 
Haven. The burial of forests was observed at Frankfort, Mus- 
kegon, and elsewhere, and is a relatively common phenomenon. 
In closing up the treatment of the forests, the general statement 
may be made that an advancing dune destroys the entire forest 
vegetation. Where this rule meets with any exception, it is an 
exception that in no real sense invalidates the main proposition. 
The encroachment of a dune upon a swamp is of less com- 
mon occurrence than encroachment upon forests, because forests 
aéso much more common than swamps along the lake shore. 
The best examples of dunes advancing on swamps were seen at 
Dune Park, where there are a number of swamps that run more 
or less parallel with the lake shore. Fig. 9 gives a good impres- 
sion of the general appearance of things in’the vicinity of Dune 
Park. In the foreground is a pool and bulrush swamp upon 
Which the dune is encroaching. Beyond the wooded ridge at 
the center is another swamp of the same type, which is suffering 
the same fate. In the distance there can be seen the crest of a 
dune, which is advancing upon a chain of forest-clad hills. 
The dune which is shown in the foreground of fig. g encroaches 
“Pena pool in which there is an abundance of aquatic plants, 
such as Nymphaea odorata, Nuphar advena, and Pontederia cordata. 
These plants are soon destroyed, of course, but it is surprising 
how long it is before they die. Leaves of Nymphaea and Nuphar 
have often been seen raised above the sand, a meter back of the 
Present margin of the pond. These plants must have been par- 
ee oo for some weeks, and yet the leaves woe ot 
depth w : all. Indeed, an oak tree buried to an equa hE of 
the ct d have succumbed entirely. Around the epost? 
This ay a luxuriant growth of the bulrush, ee ie 
when oni ‘ee gives up the struggle, etiolation sn a 
ance of : an basal portion of a stem is buried. : Fedge 
there are : sae sshuike ees: pe deiee?” ? of stem 
tags etiolated rings alternating with green rings 
