1922] Peattie,—Coastal Plain Element in Flora of Great Lakes 61 
ENDEMIC SPECIES OF THE GREAT LAKES. 
Many endemic species, wherever they may occur, are closely and 
obviously related to some other species of characteristic range, so 
that it is common to speak of a given endemic as “derived” from 
some other species. And where a variety of a species is endemic 
there is usually no doubt that the variety is a geographic, as well as 
an evolutionary, offshoot from the true species. 
In the flora of the Great Lakes there are a number of endemic plants 
and around Lake Michigan, where most are represented, some of them 
such as Eleocharis caribaea var. dispar (E. capitata var. dispar) are 
undoubtedly of coastal plain origin. In consideration of their clear 
derivation, it has been thought reasonable to reckon them among 
the total of the coastal plain element in the flora of the Great Lakes. 
Types GENERAL IN AciD Sorr. 
There are a certain number of plants which might by some be 
considered coastal plain species but which are too general in distribu- 
tion off the coastal plain to belong in that category and yet they are 
too restricted to be classed as general types of eastern North America. 
Such a plant is Eriocaulon septangulare (E. articulatum) which is 
found locally on acid, sandy or peaty shores and extends inland 
particularly over the granitic or acid areas of the northern United 
States and southern Canada. "This plant and others like it I have 
called a type general in acid soil and such plants have not been reck- 
oned into the synopsis of inland extensions of coastal plain species. 
ForMER EXTENSIVE DISTRIBUTION OF COASTAL PLAIN SPECIES. 
Trying now to account for the presence in the Middle West of the 
coastal plain flora as we have defined it, we may consider the possible 
methods of distribution by which it could have spread as it has. 
It must be remembered that many of the coastal plain types which 
occur around the head of Lake Michigan make a * jump "—that is, 
they are lacking or almost entirely lacking from the intervening area. 
If such species are found one thousand miles apart, without inter- 
vening stations, it 1s obvious that this remarkable distribution is 
not to be accounted for by that stock method—a most overworked 
and uncritical method—of dispersal by birds!, nor yet by winds. 
Were it by winds, we might expect to find these types as abundantly 
away from the Great Lakes as near them. 
1See Fernald, Botanical Expedition to Newfoundland, Ruopora xiii. 143—145 
(1911). 
