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1899] DUNE FLORAS OF LAKE MICHIGAN 187 
the small inland lakes and worked over by the winds, exactly as 
described in the preceding pages. The dune-forming winds at 
Crystal lake are easterly winds, chiefly because the source of sand 
is on the west side of the lake, and it is on the west shore that the 
dunes are located. There are typical Ammophila dunes at this 
point. Among the other plants growing here are Artemisia, 
Cnicus, Populus, Cornus, Prunus, Lathyrus, GEnothera, Corisper- 
mum, Calamagrostis, Elymus, and Juncus. At no place on Lake 
Michigan was a more typical and varied beach and beach dune 
flora observed than on the west shore of Crystal lake. 
2. Dunes of slow growth (secondary embryonic dunes). 
Dune formation is by no means confined to the upper beach, 
Dut may take place anywhere that the sand is able to collect, 
Provided the plants at that place are fitted to be dune-formers. 
The formation of dunes on the dune-complex and on rejuvenated 
ee is essentially like that on the upper beach, and will be 
Hiscussed later. New dunes of a very interesting type are in 
Process of formation on many fossil beaches and on the gravel 
terraces. As has been previously stated, the terraces and fossil 
eee better protected from the wind than is the upper 
‘ga there is in consequence not only a more luxuriant 
bee As also a different plant assemblage. The sand which 
ously ce these places, though less in quantity and less furi- 
Proper = nevertheless is capable of dune formation if the 
a amy Species are present. Several of the beach dune: 
Up smal] °ccur on the terraces and fossil beaches, and build 
runus ws: ‘Among these are Ammophila, Calamagrostis, 
» and Populus, 
ne Bee ime-formers on terraces and protected fossil 
iS grass = the most interesting is Andropogon scoparius. 
already eae Ws in tufts and is very abundant, as has been 
Collecteg. A “Saag each tuft a mound of sand has often 
‘tea of fan tograph showing the striking appearance of an 
*pPearance is pe omes was unfortunately spoiled, but its 
uch like that of an area of roches moutonnées, as 
