497 
C. Alleghanian—Ozark District. 
Geographically this district comprises the Alleghany Plateau west of the 
Appalachian ranges of mountains, the more level surfaces of Ohio, Indiana, 
southern Illinois, southwestern Michigan near Lake Michigan, and the Ozark 
areas of Missouri with an extension southwestward into northwestern Arkansas, 
Indian Territory, Oklahoma and Texas. Three phytogeographic areas may be 
recognized, viz., (1) the Lacustrine Area comprising western New York 
western Pennsylvania, northern Ohio, northern Indiana, southwestern Michigan; 
2) the Kentucky-Tennessee Area including southern Ohio, Indiana, Illinois, 
nearly all of Kentucky, central Tennessee, northern Alabama along the Tennes- 
see River; (3) the Ozark Area, which includes nearly all of Missouri, north- 
western Arkansas, Indian Territory, Oklahoma, northern and central Texas. 
The flora of this district is prevailingly one associated with the dominance of 
hardwood or deciduous-leaved trees, many species of which form a high forest 
with secondary trees and shrubs and herbs on the ground beneath. 
a) Lacustrine Area. 
This area lies in proximity to and the distribution of its plants is more or 
less controlled by three great inland lakes: Ontario, Erie and Michigan. For 
example, the phyto-geographer finds a difference (amounting to 233 species) 
between the west end of Lake Erie in the neighborhood of Sandusky Bay and 
the east end near the city of Buffalo. 
Thus the following plants found along the south shore of Lake Erie occur farther north than 
en else in this part of the country*). Viola pedatifida, Desmodium (Meibomia) sessilifolium, 
D. illinoense, Baptisia leucantha, Petalostemon candidus, P. violaceus (= u; ), Ammania 
cocceinea, Rotala ramosior, Eryngium yuccaefolium, Aster Shortii, Boltonia asteroides, Eclipta alba, 
Helianthus grosseserratus, H. hirsutus, H. mollis, H. occidentalis, Eupatorium altissimum, Kuhnia 
eupatoroides, Liatris squarrosa, Solidago ER Phacelia Purshii, Gerardia auriculata, Serkieris 
fzelia) macrophylla, Lippia lanceolata, Euphorbia dentata, Populus heterophylla, Smilax bona- 
nox, Smilax Fee Juncus scirpoides, Carex REN C. Shortiana, Poa brevifolia, Equisetum 
laevigatum 
This difference is due to several factors operating; (r) the prevailing south- 
west winds, which traverse the length of the lake and keep Buffalo cool; 
(2) the crowding of the winter ice in the spring at the east end of the lake 
as to prevent navigation three weeks or more after Sandusky is clear; (3) the 
mean temperature in summer is four degrees lower at Buffalo than at San- 
dusky due to the position of the lake; (4) the position of the eastern end of 
Lake Erie is such that it is protected from cold northwest winds of autumn. 
The influence of these three lakes is shown also in New York where with 
the central finger lakes of which Cayuga is the largest the climate is greatly 
ameliorated in their immediate neighborhood. The shore of Lake Erie is 
ı) MoseLey, E. S.: Climatic Influence of Lake Erie on Vegetation. American Naturalist 
XXXI: 60 Jan. 1897. 
Harshberger, Survey N.-America, 32 
