292 
The Ohio Naturalist. 
[Vol. V, No. 4, 
are more or less supplied with red coloring matter, probably a 
result of the low temperatures to which they haye been exposed. 
The buds continue to expand and the enclosed stem becomes an 
active, growing plant. Later it may become attached in the 
mud by roots from the basal end. 
The bladders are much reduced, or almost entirely absent 
from the stems bearing the hibernacula. while they are found 
within the buds in an immature stage. The spaces between the 
leaves that go to form the hibernacula. contain various algae, such 
as Oscillatorias, Desmids, Diatoms and other unicellular forms. 
Fig. 1. Two hibernacula of Utricularia vulgaris on a single stem. 
Fig. 2. Longitudinal section through the middle of a hibernaculum of Utricularia 
vulgaris. 
Fig. 3. Longitudinal section of an immature bladder. 
The hibernacula of the Potamogetons, the Myriophyllums 
and Philotria canadensis, are usually more elongated and the 
leaves less crowded than those of Utricularia. The buds do not 
rise to the surface of the water in the spring but remain in the 
mud and develop roots and leafy shoots which grow upward 
toward the surface of the water. 
The Lemnas, Wolffias and Spirodela produce pocket shaped 
buds, which contain the next years’ stem, and like those of 
Utricularia, usually sink to the bottom of the water on the 
approach of winter and in the spring rise again to the surface 
and develop into floating plants. 
