124 PLANT LIFE OF ALABAMA. 
and flow of the tide, wind their way to the inlets of the Gulf. The 
fine sand forming the surface as well as the subsoil is closely packed, 
permitting the water to permeate but slowly, and in consequence is 
overflowed after every rainfall. The great poverty of the soil is mani- 
fest in the stunted growth of pines scattered over these flats and the 
dwarfed cypress and white cedar lining the sandy banks of the streams. 
The surface is exsiccated during the dry summer season, and supports 
a scanty growth of poverty grasses, particularly Aristida spiciformis 
and A. palustr/s, and the toothache grass (Campulosus aromaticus), 
with its stout aromatic rootstock deeply buried in the compacted 
sand, with which are found Scleria torreyana and Liliwn catesbaei, 
and, during the late autumnal rains, the rare (yrostachys brevifolia, 
known also from western Florida. 
Paludial arboreal associations (cypress brakes).—The bottom lands of 
the Mobile River and the islands in the delta, overflowed at every 
freshet, are covered with a high forest of deciduous trees, common to 
them and the lowlands of the same character along the Tombigbee and 
Alabama rivers in their course through the Louisianian area. Where 
the banks are almost perpetually submerged they are covered with 
cypress. This largest of the Atlantic forest trees was formerly found 
in the upper part of the river delta in great perfection. The mighty 
trunks rise to a total height of from 100 to 120 feet and over, with a 
diameter, measured above the buttresses which expand the bases, of from 
3 to over 5 feet. The annual rings of growth are extremely narrow 
and difficult to count. On close investigation the age of full-grown 
trees can be estimated to vary between 300 and 500 years. They are 
the sole survivors in this part of the North American continent of an 
archaic type. The assemblage of these monarchs of the-forest in the 
compact cypress brake, surrounded by the peculiar cone-shaped 
excrescences (cypress knees) rising from their roots 1 to 2 feet and more 
above the dark unruffled surface of the water, presents a feature in 
the arboreal flora of the present at once strange and imposing. Asa 
result of the large demand for their valuable timber, the resources of 
these brakes in the delta and on the lower Alabama and Tombigbee 
rivers have been almost exhausted, and in this district the manufac- 
ture of cypress lumber has at present nearly ceased. The supplies of 
this timber neeJed for the manufacture of cypress shingles at Mobile 
are at present mostly drawn from the more remote brakes on the 
rivers named and their principal tributaries along their lower course. 
In these brakes the tupelo gum (Wyssa aquatica) is the only associate 
of the cypress, which it rivals in size, and the Carolina swamp ash is 
the only tree of small size thriving in the gloomy shade beneath these’ 
trees. 
In the mire of the swamps above the level of long-continued overflows 
a variety of hard-wood trees mingle with the cypress and finally super- 
