TRbooora 
JOURNAL OF 
THE NEW ENGLAND BOTANICAL CLUB 
Vol. 24. April, 1922 No. 280. 
THE ATLANTIC COASTAL PLAIN ELEMENT 
IN THE FLORA OF THE GREAT LAKES. 
DoNarp Curnoss PEATTIE. 
Ir has long been known that the flora of the sand dunes and shores 
of the Great Lakes, and particularly of those at the head of Lake 
Michigan, contains some remarkable elements, for the vegetation of 
this area is often in sharp contrast to that of the bordering forest and 
prairies. It has further been known that many specics are of coastal 
plain derivation, and this fact is so anomalous in the Middle West 
that for some time it has struck the attention of observers. 
It is hardly to be supposed that the presence of the coastal plain 
flora in the neighborhood of the Great Lakes is to be explained on 
the basis of any accidental or deliberate introduction. Few of the 
coastal plain plants are of an aggressive or weed-like nature. There 
is no evidence that plants of conservative habits and habitats, such as 
Rynchospora macrostachya, Drosera longifolia, Polygala cruciata or 
Utricularia gibba follow the footsteps of man or occur as casual weeds. 
Therefore, the presence in the flora of the Lake Michigan region 
alone of some sixty species of plants which are not found, or are but 
rarely found elsewhere off the true coastal plain, has long awaited 
some sort of explanation. With the plan of solving this problem, I 
went into the field in Indiana and Michigan in the summer of 1920 
and collected as many coastal plain and other types of plants as I 
could. But in work at the Gray Herbarium of Harvard University, 
it at length became evident that the problem of this anomalous dis- 
tribution could not be solved without reference to the flora of the Great 
Lakes as a whole and accordingly a study of the costal plain element 
of the other lakes was undertaken. 
