296 . THE AMERICAN MIDLAND NATURALIST 
not even in case of Nuphar variegata, is that the seeds germinate 
above the water line in or on mud. In this case no aquatic foliage 
whatever is produced [e.f.]. The leaves are the usual thick aerial 
ones with short stout petioles. They are even firmer and propor- 
tionately smaller than the floating ones. Even when not germi- 
nating below the water line, but when embedded in mud the 
seeds send out the elongated epicotyl [f.]. MN. advena alone seems 
to have this last environment. ‘The variation of shape in these 
aerial leaves is also a gradual one, the very earliest, however, 
are never as narrow as the younger aqautic ones. In fact should 
the water of a .pond lower and leave plantlets with one or two 
aquatic thin leaves exposed to air, no more aquatic foliage is 
produced, but only aerial thicker leaves. Such changes from 
water exposure to air exposure of foliage and back again are rapid 
and frequent, due to the fact that the rise and fall of the so-called 
“floating islands’. or musk-rat feeding-places occur. These 
animals undermine large patches of root-entangled bottom which 
rises and small islands float about. As the other plants on them 
die these patches often sink again. Around the muskrat “‘runs”’ 
these ‘‘floating islands’’ dip abruptly into deep water, and all 
the stages of Nuphar seedling environment may be found within 
the area of single square yard. 
North Bankson Lake is muddier than the other lake as it 
has in very recent times been cut off, by a sand-bar raised by 
wind and wave action. It is now much more sheltered and has 
rather large areas of these ‘floating islands’’ which have become 
a tangled mass of roots of Carices, Cypert, Scirpi, Junct, Eripohorum 
and principally Rhychospora macrostachya, Dulichium arundinaceum 
Hermicarpha micrantha, Fuirena squarrosa, one or two species of 
Fimbristylis and Eleocharis, many tall grasses Xyris flexuosa, Pel- 
tandra virginica, Sparganium minimum, Eriocaulon septangulare, 
and nearer the water line, Utricularia intermedia and minor growing 
with Nuphar advena seedlings. It is very unsafe to venture upon 
these patches without the aid of planks as they are real floating 
quagmires. Changes in environment to meet rapidly varying 
conditions are so frequent that the Nuphar seedlings accommodate 
themselves apparently to all the habitats in rapid succession. I 
have even found Nuphar advena seeds germinating in the almost 
dry drained bottom of a pond south of South Bend, where the 
older plants deprived of sufficient moisture were rapidly drying off. 
