LEITNERIA FLORIDANA. i pi 
perhaps slenderer. In a letter accompanying this note, 
Mr. Hemsley states that he also suspects that all of the 
Leitneria material is of one species. 
Dr. Chapman informs me that in Florida the original 
stations of the species on the coast have long since been 
washed away, but he afterwards found it inland, where, 
nevertheless, its distribution is not known to be more than 
very restricted. Whether the Texan material referred to 
above was actually gathered along the Brazos, or possibly 
further east, where Drummond also collected extensively, 
the.occurrence of Leitneria in Missouri is, therefore, very 
remarkable. But the investigations of Mr. Bush have 
shown that this part of our State is a meeting-point for the 
floras of the Middle States, the eastern Gulf region and 
Texas.* 
The reason for the extension of the Gulf Flora noted, 
appears to lie in the deep swampy character of much of 
the land along the general course of the Mississippi River 
in southern Missouri and northern Arkansas as well as 
further toward the Gulf. This entire region is noted for 
the present fluctuations in its water level, due to artificial 
elevation of the immediate bounds of the great river and 
its tributaries, some of which nevertheless are destroyed 
almost every year during freshets; but presumable natural 
changes, and the large measure of success which has been 
reached in confining the streams to their channels and 
inducing a more rapid flow near the mouth of the Missis- 
sippi, have resulted in lowering the maximum average level 
of the water in case of inundation, and a far more per- 
fect drainage of the lowlands than formerly, during the 
season of low water. This seems to be indicated quite 
clearly by a study of the cypress trees of the region. I 
believe it is generally admitted that the level to which the 
root knees of the cypress rise in wet cypress swamps cor- 
responds closely with the normal flood water level. This is 
* Fifth Garden Report, 140. 
