Feb., 1905.] Hibeniacula of Ohio Water Plants.. 
291 
For the species of Mononyx, tables will be found in Montan- 
don’s paper; the Mexican and Central American forms of Pel- 
ogonus are tabulated in Vol. II, Rhynchota of Biologia Centrali 
Americana, but there is no work on Gelastorcoris outside of the 
notes under the species in the last mentioned work to help in 
separating them. 
New York City. 
THE HIBERNACULA OF OHIO WATER PLANTS. 
H. York. 
Many aquatic plants that root at the bottom of streams and 
lakes die down in the autumn and pass the winter by means of 
tubers, bulbs and rhizomes, while others have developed a 
peculiar type of winter propagative buds at the tips of the stems. 
These curious buds are found in many of the pond weeds, stone- 
worts and bladderworts. In the late summer and early autumn 
the plants turn brown and die except at the tips of the stems 
which remain alive. The tips of the stems cease to lengthen 
out and are enclosed with dark green leaves which become 
crowded and folded so closely as to form egg-shaped bodies. 
They remain on the stems for some time but finally become 
detached and sink to the bottom of the water where they escape 
the cold of winter and are scattered in various directions thus 
becoming a means for vegetative propagation. These buds are 
much shortened stems and are termed Hibernacula. 
A somewhat careful study was made of the hibernacula of 
Utricularia vulgaris since they are quite large and easily obtained. 
They begin to appear in the latter part of August and are formed 
in the manner already described, the leaves being crowded so 
closely and overlapping each other as to form green ball-shaped 
buds that are quite compact. The air spaces in the stems and 
leaves become much reduced and the cells are packed with starch 
granules which cause the buds to sink when they are detached 
from the stems. When the hibernacula first begin to develop, 
the tips of the stems and leaves secrete a mucilaginous substance, 
which surrounds and permeates the buds when they are formed. 
In the spring when the ice has melted and the sun’s rays 
begin to warm the water, the buds commence to grow. The 
starch grains that were stored up in the preceding autumn are 
used in the building of the new stem. Bubbles of gas are set free 
which are held in the mucilaginous covering and cause the buds 
to rise to the surface of the water. The hibernacula have 
changed somewhat in appearance from that in the fall as they 
