TYPICAL SWAMP AREAS. 59 
former tree. The groves of young cypress are not so un- 
mixed in the Bertig region as those of the tupelo. It can 
be seen from the photographs that a considerable amount 
of undergrowth accompanies the cypress; it consists of 
young tupelos, Cephalanthus occidentalis, Mikania scan- 
dens, etc.* (Plate 15.) 
The young trees early acquire the conical butt and the 
roots are soon lifted above the surface of the ground or 
water, forming the conspicuous ‘* knees’”’ of the cypress 
forest. (Plates 16, 17 and 18.) It is very noticeable in 
the Bertig region that the young and middle aged trees 
have the conical base, while the oldest trees have not, 
although in the latter case the knees are enormously 
developed. This is not true of the tupelo, as the base 
continues to increase in size during the life of the tree. 
The enlargement of the base of the cypress does not seem 
to be attended by decay and death, as in the tupelo, but 
this enlargement, as well as the development of the knees, 
accompanies the growth in swamps. When growing in 
dry soil, neither phenomenon occurs. If, as currently 
reported, there has been a general subsidence of these so- 
called «‘ sunken lands,’’ it may account for the fact that 
the older cypresses have not the enlarged base, that is, 
they may have occupied relatively higher and drier ground 
until they were well grown and not subjected to the con- 
ditions which cause the enlargement of base. After sub- 
sidence the newer roots might have developed the knees 
which are now present. When the usual waters have sub- 
sided, the writer has observed these upgrowing roots to 
have attained a hight of eight feet above the surface of 
the ground. The general impression exists that these are 
‘< breathing roots’’ and serve the purpose of conveying 
oxygen to the parts submerged in underlying mud. 
* However, near the confluence of the Varner and St. Francis Rivers, 
fifteen miles above Bertig, there are large groves of cypress covering 
many square miles in which very few other trees are found. 
