50 
FOURTEENTH REPORT. 
INVADING SPECIES. 
Nymphaea americana. 
The CastaMorNym phaea Association. 
This association of rooted aquatics with floating leaves and flowers 
occurs sparingly in the lakes of the region. In the ponds and smaller 
lakes, where the water is quiet, Nymphaea americana and CastaUa odorata 
form their typical zone. In Douglas Lake this association occurs only 
in protected hays, where it is represented by Nymphaea americana grow- 
ing in water two to four feet in depth. The association is very open and 
seedling plants are usually abundant, suggesting reproduction by seeds 
rather than growth of the rootstocks. A number of the rootstocks are 
undoubtedly uprooted by the ice during the winter. The stems catch 
more or less of the uprooted and floating Cliara, Elodea, Potamogeton 
and Myriophyllum — some of which, particularly Myriophyllum and 
Elodea . frequently take root and develop as secondary species. 
In the larger lakes this association is succeeded by the Eeirpus mlidus 
association, or on very shallow shores by the Eleocharis palustris vigens 
association. In boggy situations and in the very small lakes, such asso- 
ciations as the Typha , the Car ex filiform is , the Menyanthes-Eagitta/ria or 
the Ciia maeda phne associations may displace this association, depending 
upon the distribution of seeds or the presence of the plants of these asso- 
ciations in the immediate vicinity. 
List of the Species of the Castal ia-X ym phaea Association: 
DOMINANT SPECIES. 
CastaUa odorata. Nymphaea americana. 
(Cast alia tuherosa. 
SECONDARY SPECIES. 
Elodea canadensis. Myriophyllum spieatum. 
i allisneria spiralis. 
RELIC SPECIES. 
I *o i a m ogeto n na ta ns. 
INVADING SPECIES. 
Eeirpus ralidus. Eleocharis palustris vigens. 
Tli e .1 fe n ya n 1 hes-Eagi t ta ria A ssocia lion. 
This association of aquatic plants is represented very sparingly in 
the region of Bessey Greek, a bog southeast of Douglas Lake and along 
parts of the little streams running thru some of the cedar bogs. As 
a rule it is represented by Eagittaria latifolia, with quite narrow 
leaves. Less frequently the Eagittaria is accompanied by Menyanthes. 
Only in Bessey Creek did Eparganium simplex occur with it. Epargan- 
ium grew out into deeper water than Eagittaria was observed but in 
