HARPER: BOTANICAL CROSS-SECTION OF Mississippr 395 
Relation of flora to precipitation and soil texture. The absence 
of Takodium imbricarium, Magnolia glauca, and other bog plants 
from northern Mississippi is correlated with the seasonal distribu- 
tion of rainfall, among other things. In the greater part of the 
coastal plain, summer is the rainy season; but in the “ Mississippi 
embayment” portion, which is farthest inland, the winters are 
wetter than the summers, just as in the interior hardwood region, 
of which this might be regarded as forming a part. At Water 
Valley, Yalobusha County, which is pretty close to the center of 
the northern half of Mississippi, meteorological records for a 
period of twenty years show that only 30.3 per cent of the normal 
annual precipitation comes in the four warmest months, June to 
September, and 41.9 per cent in the six warmest months, May to 
October.* (March is usually the wettest month and October the 
driest.) 
This type of seasonal distribution of rainfall makes all streams, 
and the ground-water too, high in spring and low in fall; while 
in the pine-barren portions of the coastal plain the greater evap- 
orating power of the sun in summer is largely counterbalanced by 
the increased rainfall at that season, and consequently the water- 
level is much more uniform there, and conditions are favorable 
for the development of peat and of bog plants. Ponds and 
swamps are scarce in northern Mississippi, except in the ‘‘delta,’’ 
where they are caused by the topography, in spite of the climatic 
conditions just described. 
Another factor perhaps still more important in determining 
1820, first met it at Cypress Bend, about 20 miles below the mouth of the Arkansas 
River; and one of the bends near aay is named “Spanish Moss Bend.”” The 
same plant was reported from along the Cumberland River in Stewart County, 
Tennessee, by Dr. J. M. Safford, state ign of Tennessee, in Garden & Forest 
3: Si. 
* For data of seasonal distribution of rainfall in some other parts of the coastal 
Vv. 
plain see Bull. Torrey Club 37: 415~416 (footnote). 
Ann. Rep. 3: 21 5. Iori. The interior hardwood region has been br 
usually a little warmer than April; and furthermore it is usually drier than April in 
the regions that have dry summers, and wetter than April in the regions that have 
wet summers, so that the figures for May to October give greater contrasts than do 
those for April to September. 
