Bickett—The Larger Aquatic Plants of Green Lake. 393 
Potamogeton pectinatus also forms about 10 per cent of the total 
weight of plants. It is distributed unevenly, but is locally very 
abundant. Elodea, Vallisneria, Drepanocladus, Scirpus, and 
Potamogeton zosterifoUus each form between 2 and 10 per cent 
and ail other species less than 2 per cent each. 
In Mendota the situation is entirely different. Chara forms a 
negligible fraction of the vegetation. Vallisneria almost takes its 
place, composing about one-third of all the plants. Several species 
of Potamogeton bulk large,—P. amplifolius about 25 per cent, 
P. Bichardsonii 10 per cent, P. pectinatus 8 per cent. Taken to¬ 
gether the species of Potamogeton total about 50 per cent. Myrio- 
phyllum forms only 4 per cent of the total and Ceratophyllum 
still less. 
It has been remarked already that both Myriophyllum and 
Ceratophyllum are deep water plants, as far as Green Lake is con¬ 
cerned; this may explain their relative scarcity in Mendota, where 
the whole deep flora is so much less luxuriant. The other differ¬ 
ences, however, must be attributed to various factors. Tempera* 
ture may perhaps hold down the Vallisneria in Green Lake, wave 
action the shallow water Potamogetons, and soil differences per¬ 
haps account for the immense development of Chara. 
The distribution of species according to depth is well marked 
in some cases, in others less so. The cases of Ceratophyllum and 
Myriophyllum have been dealt with already. In Mendota the 
greater part of these plants is found in Zone 2. Vallisneria reaches 
its greatest abundance in Zone 2 in both lakes, but is hardly found 
in Zone 3 in Green Lake, while in Mendota about 25 per cent of it 
is found in deep water. Ranunculus reaches deeper water in Green 
Lake, half of it being found in Zone 2, and one-fourth in Zone 3; 
in Mendota it is confined to Zone 1. The same is true of Chara, 
which is nearly evenly distributed between Zones 2 and 3 in Green 
Lake, and between Zones 1 and 2 in Mendota. Potamogeton ampli¬ 
folius and P. zosterifoUus are similarly distributed in both lakes; 
but P. Bichardsonii and P. pectinatus are found mostly in deeper 
water in Green Lake, while in Mendota their greatest growth occurs 
in Zone 1. 
The final averages and totals of course conceal a great deal of 
regional variation. The varying characters of different stations 
may be seen in tables 3, 4, and 5, which present the stations sepa¬ 
rately. Two general kinds of stations may be distinguished. In 
one the vegetation is not very rich and is composed mostly of 
