GENERAL PAPERS 145 
species grow. It is interesting, though, to note the occurrence 
together of such characteristically upland trees as Celtis occi- 
dentalis and Quercus Muehlenbergii with their characteristic- 
ally bottom-land congeners, C. Mississippiensis and Q. pago- 
daefolia, 
So far as can be seen, this Pulaski County station presents 
a natural extension of the recognized range of Castanea den- 
tata, though for some reason the tree is not known to extend 
beyond this single grove, less than a mile from the Ohio 
River. How it crossed the river is a matter for conjecture 
only, but propinquity suggests the belief that it entered the 
State from Kentucky. 
Quite apart from the general consideration here presented 
it may be noted that, as would be expected, no signs of the 
chestnut blight were found in the Olmstead grove. 
DWARF SHORE FLORAS 
H. Wa.LrtTon Cuiark, U. S. BIOLOGICAL STATION, FAIRPORT, IA. 
Among the areas characterized by well-marked plant asso- 
ciations or societies recognizable by ecologists, two, the tem- 
porary woodland ponds and the low area along shores of rivers 
and lakes, resemble each other in that their members generally 
represent remarkable adaptability in their relations to water 
supply, and both are accordingly regions of polymorphic or 
dimorphic species. Along shore-lines of permanent bodies of 
water stratified polymorphism, or variation of the same plant 
in different levels is frequent, as exemplified in the water 
plantain, Alisma plantago-aquatica L. and several Potamo- 
getons which have three forms of leaves, the thin semi-trans- 
parent submersed, or often linear phyllodes, the flaccid floating 
leaves and stiff erect aerial ones, or which is exhibited most 
strikingly by the water parsnip, Siwm cicutaefolium Gmel. with 
its finely cut lower leaves, serrate medium leaves, and almost 
entire upper ones. Dimorphic forms such as the water Star- 
Grass, Heteranthera dubia (Jacq.) MacM. are also present. 
In the temporary woodland ponds, although stratified varia- 
tion is present, the water parsnip being a member of the pond 
region also, there is a more marked tendency toward seasonal 
