* 
TOPOGRAPHIC AND FLORISTIC REGIONS OF 
MISSISSIPPI. 
General Considerations.—The surface of Mississippi pres- 
ents considerable diversity both in elevation and in character 
of soil. The greatest elevation known in the state, in the ex- 
treme northeastern part, is about 800 feet above sea level, 
while a fringe of flat lands five to twenty-five miles wide border™ 
ing the Gulf, is only a few feet above tide water. While this 
difference in elevation is not considered important as a climatic 
factcr in the state, it undoubtedly has an appreciable effect 
upon plant distribution, but the extent of this effect has not yet 
been ascertained. 
The north and south length of the state is somewhat more 
than 300 miles, or nearly five degrees of latitude. This is suffi- 
cient to produce a noticeable difference between the flora of the 
northernmost parts of the state and those parts bordering the 
Gulf; but when are added to this factor of climatic difference 
the ameliorating effect of the Gulf in the southern counties, and 
the greater elevation in the northern, we are prepared to expect 
important floral differences. Comparison of the floral cf the 
Tennessee River region with that of the Gulf region of the state 
reveals a marked dissimilarity. Yet this dissimilarity is due 
very largely to soil differences and other factors as well as to 
jatitude and altitude. 
Topographically and geologically Mississippi has been 
divided into ten more or less distinctly marked regions, and in 
a previous publication (1) I have regarded these as regions of 
plant distribution. Geological structure has such a direct in- 
fluence upon topography and soil, which in turn distinetly in- 
fluence the distribution of plant species, that the regions given 
below (See sketch map), will be accepted here to represent the 
floristic regions of the state. As has already been said, the 
whole state, excepting possibly a small area in the northeast- 
ern corner, lies in the Austroriparian Area; hence the divisions 
given are not major in importance, but are local and subor- 
(1) Miss. Geol. Surv., Bulletin No. 11, “Forest Conditions of Mis- 
sippi,” 1913. Notes on Flora by E. N. Lowe, p. 138. 
