1899 | ; 
DUNE FLORAS OF LAKE MICHIGAN 38 
I 
uite a 
om ve wee zs normal predecessor of the oak. 
of a more Eeeasiy Ce shown in figs. 9 and 20 may be the relicts 
Be The oak ae flora that has been succeeded by the 
|e ot get a foothold until the dune has become 
are scattered, there i ee we the lake winds. If the pines 
successfully. a Pe i for the oak seedlings to develop 
OU ie. tie fo res are more destructive to the pines than 
sprouts are less likel see are more readily burned, and basal 
oaks. Near Dune oe is is tae afterward than in the case of the 
been burned and re : there is a tract on which the pines have 
One of the m anee by the oaks. 
fin is the ap wy striking landscape features of the Dune Park 
Be), and - anes of the pines at the lower levels (pine 
cd: oes the highest summits. The oaks occupy 
a . a ion as to altitude. The reason for this dis- 
Bi itiois than ioe the pines have a much wider range of 
summits because of : oaks. The oaks are excluded from the 
they are not ee t extreme exposure to wind and cold; 
excluded from ete ytic enough for such a habitat. They are 
| ottoms, because the conditions are too hydro- 
mediate positions — The pines are excluded from the inter- 
bie f°) : ecause of lack of adaptation, but because 
Where the oaks ae one for that position than are the pines. 
pines, while the ae at all, they seem able to drive out the 
oaks. pines occupy areas that are not adapted to the 
that found on sunny 
{3 xerophytic flora 
where the adapta- 
Th 
at of the oak dunes, especially 
resembling i is a true xerophytic flora, bu 
tions are of the more southern type, 
transpiration Guws protect against heat and the excessive 
"ard slopes is eu it chica The flora on northern and wind- 
ora aaa ominantly evergreen, developing into a heath 
actic or Spine — This flora, too, is xerophytic, but of an 
tect against th YPE where the adaptations are developed to pro- 
‘tanspiratio & wind and cold and the dangers of excessive 
n which they bring. The correctness of this view is 
