116 Harper: Trip ON WARRIOR AND TOMBIGBEE RIVERS 
The higher numbers for the shrubs and trees in the first column 
are of course due principally to the fact that we traveled 145 miles 
through the Cretaceous and only 116 through the Eocene. The 
slightly greater number of woody plants in the Cretaceous list 
may be due to the same cause, and the excess of herbs in the 
second column to the fact that we landed oftener in the Eocene 
region; but there is also a possibility that this may be a part of 
the general tendency for woody plants to be most numerous in 
climax forests and herbs in pioneer forests —the Cretaceous region 
having of course been above the sea longer than the Eocene. 
A few words on habitats should be inserted here. The favorite 
habitat of the A/nus, Aster, Onoclea, Osmunda, and Adiantum was 
at the line of contact between the Cretaceous and second-bottom 
deposits, where water is perpetually seeping out, on shaded bluffs 
of moderate height. In such places the four herbs just mentioned 
usually hang down against vertical cliffs, which in the case of 
the Oxoclea and Osmunda at least is somewhat of a departure from 
their habit elsewhere. The Diéanthera, Ammannia and several 
Cyperaceae not seen often enough to be mentioned in the above 
table commonly grow on gently sloping clayey Eocene strata near 
the bases of bluffs, where they are usually moistened by trickling 
water from above when the river is low and completely submerged 
when it is high. The Phoradendron seemed to grow oftener on 
Populus than on any other tree. It was also frequent on Acer, less 
so on Betula, occasional on Platanus, but apparently never on 
Salix, Planera, or any of the conifers. 
If the hammock and high bluff plants, which happen to be 
mostly trees, be disregarded, the most striking features of both 
lists are the scarcity of evergreens and the large proportion of 
vines. This seems to be characteristic of most alluvial forests in 
temperate eastern North America, especially those of the Missis- 
sippi Valley type.* A dense tangle of at least half a dozen species 
of vines was nearly always in sight, giving the banks in some 
places, especially where low and swampy, somewhat the appear- 
ance of the proverbial tropical jungle. (Many of the species, 
curiously enough, have near relatives in tropical America.) 
The parallel column arrangement brings out the relatively 
*See Ann. N. Y. Acad. Sci. 17: 69-73. 1906 ; Torreya 10: 62. Mr IgIo. 
