154 THE FLORA OF MISSISSIPPI. 



topography, however, is due to a peculiarity of the material 

 eroded. For 10 to 20 miles back from the Delta edge a 

 thick deposit of loess silt overlies the surface 30 to 75 feet 

 thick, and forms the basis for the soil and for the peculiar 

 character of erosion into vertical faces. This loess is a 

 fine yellowish calcareous silt containing numerous snail 

 shells, thickest next the river, and thinning rapidly to an 

 edge at the eastern margin of the region. 



On account of the lime content the soil derived from 

 this material is more fertile than that of the plateau farther 

 back, and supports a vegetation somewhat different. In 

 this region the hill flora of the plateau and the lowland 

 flora of the Delta come into competition, with the result 

 that the flora, while of hill type, has some distinct charac- 

 ters derived from the Delta. 



The extent of the region from north to south is such 

 that, while the distinctive features of the flora persist, 

 some species appear in the southern part that are not found 

 farther north. 



The tree flora of the Loess hills is almost entirely of 

 hardwoods. Pines are not at all a common feature, ex- 

 cept as a second growth in old thrown-out fields or other 

 openings. Red cedars {Juniperus Virginiana) are not 

 uncommon on the steep slopes, but was probably not part 

 of the original flora. The gray moss {Tillandsia Msneoides) 

 drapes the trees, being especially abundant in the more 

 southern parts, and gradually disappearing before the 

 northern boundary of the State is reached. Myrica cerijera 

 and Pteris Cretica have been observed toward the southern 

 end of the region, but so far not farther north. Other 

 herbaceous species that have been found in the region 

 not north of Natchez are the following: 



Heterotheca Lamar ckii, Parthenium Hysterophorus. 



Croton Texensis, 



The beautiful white Cherokee rose (Rosa Cherokee) 

 is very common and striking in the southern half of this 

 region, but is also found on the loam soils east of the Bluff 

 region in the same latitudes. 



