RECOGNITION OF CHARACTER OF SOILS. 



507 



as well as, frequently, from that of the adjacent uplands; and 

 though level and fair to see, these hammocks are usually un- 

 thrifty and last but a short time under exhaustive cultivation. 

 Accordingly, their forest growth is prevalently that of the 

 poorer class of uplands, viz., small-sized post and black-jack 

 oaks, and in the low ground depauperated water oak, or less 

 commonly willow oak, of the low, stunted type indicative of a 

 a soil of inferior productiveness. The luxuriant growth of the 

 present alluvial bottom is often seen within a few feet of the 

 unthrifty vegetation of these hammocks. It is usually only in 

 the limestone regions, and in the lower course of the larger 

 streams, that the hammocks or second bottoms are found to be 

 of good fertility. 



The Tree Growth of the First Bottoms. The Cypress. 

 Among the trees occupying the low ground of the first bottom 

 in the southern Mississippi states, the deciduous cypress ( Tax- 

 odium distichmn) deserves special mention as an example of 

 extreme variation in form. In sloughs and swampy tracts, as 

 is well known, the cypress grows with roots submerged 

 throughout the season, excepting only the excrescences known 

 as " knees," which project above the water, probably perform- 

 ing some function in connection with the aeration of the root, 

 which is essential to the root functions in all plants. The 

 trunk rising from the water is supported by numerous pro- 

 jecting buttresses for from 8 to 15 feet above the water: higher 

 up it becomes cylindrical for a height of from 40 to 70 feet, 

 then divides up into a few widely spreading, thick, almost 

 conical branches, whose twigs and foliage form an almost level 

 surface to the head. This level-topped forest growth char- 

 acterizes at once the submerged areas of the river and coast 

 swamps. 



But the cypress is by no means confined to the swamps and 

 sloughs; it is also found occupying the better class of hammock 

 lands, u or i^ feet above water level. In this case, however, 

 the tree assumes a shape and growth so wholly different from 

 that described above as to lead to a popular assertion of a dif- 

 ference of species. As a matter of fact, however, the cones of 

 these upland cypresses, when dropping into the water be- 

 low them, reproduce exactly the common swamp form. The 

 extraordinary difference in the aspect of the tree under these 



