De.nniston—The Larger Aquatic Plants of Lake Mendota. 499 
cryptogamic flora. Third, the aphotic zone, where no light-de¬ 
manding organisms are to be found. 
Magnin (7) names five zones according to the main plants found 
in each. Beginning at the shore, they are: (1) Phragmitetum, 
(2) Scirpetum, (3) Nupharetum, (4) Potamogetonetum, (5) 
Characetum. The first two zones extend to a depth of 3 meters, 
the third to 4 meters, the fourth to 6 meters, the fifth to 12 me¬ 
ters. 
In Lake Mendota there appears very little distinct zonation of 
plants. Except in the bays, they are mostly of the submerged 
type. Near the mouth of Pheasant Branch Creek, Scirpus oc¬ 
curred near the shore, farther out were Castalia and Nymphaea, 
followed by several species of Potamogeton and Najas. These cor¬ 
respond closely with the species found in the four last-named 
zones of Magnin. 
Flowers or fruits were found on all the species of Potamogeton 
with the single exception of P. alpinus. Vegetative methods of 
reproduction are also common, such as runners, winter buds, and 
fragments of stems. All the flowering plants in this list are 
perennials with the exception of Najas flexilis. 
Two of the larger plants found in the lake are usually not at¬ 
tached to the substratum, namely, TJtricularia vulgaris in shallow 
water, and CeratopJiyllum demersum in deeper water. The lat¬ 
ter plant often appears to be rooted when the stems become bur¬ 
ied in the bottom. 
Calcium carbonate was found incrusting the stems and leaves of 
four of the six species of Potamogeton. Pond (5) states that this 
coating probably does not injure the plants and may offer some 
protection from aquatic animals. 
The five most abundant species, in the order of their abundance 
are: Vallisneria spiralis L., Najas flexilis (Willd.) Kostk. & 
Schmidt, Potamogeton Richardsonii (Benn.) Rydb., Potamogeton 
zosterifolius Schumacher, Potamogeton pectinatus L. 
In addition to these there were found in less abundance: Pot¬ 
amogeton luceus L., Potamogeton alpinus Balbis, Potamogeton 
amplifolius Tuckerm., CeratopJiyllum demersum L., Myriophyllum 
verticillatum L. var. pectinatum Wallr., Scirpus validus Vahl, 
Elodea canadensis Michx., Ranunculus aquatilis L. var. capilla- 
ceus DC., Nymphaea advena Ait., Castalia odorata (Ait.) Wood- 
ville & Wood, Lemna minor L., Lemna trisulca L., Wolffla Colum¬ 
biana Karst., TJtricularia vulgaris L. var. americana Gray, CJiara 
species, Cladophora species. 
