168 BOTANICAL GAZETTE [MARCH 
gressive movement of them all out into the lake. As a whole 
the three beach zones slope gradually and somewhat evenly 
upward, toward the dunes or bluffs beyond; depressions, how — 
ever, are not at all uncommon, and at times they reach downto — 
the water level, so that a beach pool results. 
The life conditions are much less severe than on the middle — 
beach, and chiefly because of the freedom from the wave action 
of the winter storms. The exposure to the sun is almost a 
great as on the lower zones, but there is more protection from 
the wind because of the abundance of driftwood. The protec — 
tive influence exerted by piles of débris is finely shown on the | 
beach at North Manitou island. The upper beach along the 
south shore of the lake is usually very sandy and comparatively 
free from driftwood, while the North Manitou beaches are col 
posed chiefly of gravel and shingle with heaps of driftwood piled 
about in the greatest confusion. The North Manitou flora is one 
of marked luxuriance, compared with the more southern typ: 
and many mesophytic species are able to get a foothold in a q 
more genial conditions there obtaining. The decay of the drift- | 
wood may also add no inconsiderable portion to the food mater 
ials of the beach plants. 
The flora of the upper beach is much richer than that of the 
middle beach, both in species and in individuals, but here # 
there the vegetation is so sparse that the tone to the landscape 
is given by the soil. Inthe region as a whole the most chara 
teristic species of the upper beach are Artemisia caudata and 4: 
Canadensis 3 
At nearly all places visited between Chicago 4 
island Artemisia was present and commonly in abundant’ 
Another plant associated almost everywhere with Artem® 
is Cnicus Pitcheri; this thistle is seldom so common as pei 
but scattered specimens are pretty sure to be discovered or 
* Typical forms of both Artemisias have been found, as well as all ee 
gradations, and it is all but hopeless to try to determine which is the mo pubes 
without careful examination of all the plants in time of fruit. Both species 
cent in beach and dune habitats, although A. Canadensis is the more 5 
nd Beavel 
