56 MISSOURI BOTANICAL GARDEN. 
its maximum mark, observations were begun. In open 
spaces where the water is sufliciently quiet, the Polygonum 
densiflorum seems to be the first in order of succession of 
those plants which obtain a foothold in the soil and lift 
themselves out of the water. A large proportion of the 
river bottom is covered with Myriophyllum, Ceratophyl- 
lum, Potamogeton and Cabomba, and this filling up of the 
channel and consequent slowing down of the current ren- 
ders it possible for such amphibious plants as Polygonum 
and Zizaniopsis miliacea, which succeeds it very closely, to 
secure a foothold. (Plates 11, 12, and 13.) 
In a similar locality on the Varner River, near Kennett, 
Missouri, the Polygonum was found and associated with it 
Typha latifolia and Peltandra undulata. In many quiet 
places clearof larger growth, the waterisliterally covered with 
Azolla Caroliniana, with a considerable amount of Lemna 
minor and occasional plants of Ricciocarpus natans. Going 
shoreward the Polygonum still persists in abundance, Pel- 
tandra increases, Saururus cernuus appears and is almost 
equally represented. Sium cicutaefolium appears in this 
zone also. A willow undergrowth marks the beginning of 
what may beconsidered the next zone, and, quickly follow- 
ing the willows, one notes the Cephalanthus occidentalis 
which soon becomes conspicuous. Where the underbrush 
is interrupted, immense areas of Nelumbo are found inter- 
spersed with Nuphar advena, the great leaves*crowded 
together in dense masses. In this zone closely following 
the button bush and willows the tupelo gum (Nyssa uni- 
flora) and the bald cypress (Taxodium distichum ) first 
make their appearance, and the characteristics of these two 
trees and their relations to the swamp lands are worthy of 
a thorough investigation. 
Nyssa uniflora. 
In very early spring when the areas in which the tupe- 
los are growing are flooded, one may find the inch long 
