﻿LIVING PLANTS 



pondweeds, bladderworts and stoneworts 

 which root in the mud at a few feet below the 

 surface. With the approach of autumn the 

 tips of the stems grow in the form of a thick 

 shoot with short, crowded leaves which are 

 termed hihernacula. The hibernacula finall\' 

 break loose from the stem, which dies, and 

 sink to the bottom before ice formation sets 



%^ 



c. 



Fig. 9. — a. Hibernaculwni ot Utricnlaria in October, b. Ter- 

 minal portion of stem in swmmer. c. Hibernacnlum of Philo- 

 tria Canadensis (Elodea Canadensis), d. Terminal portion of 

 stem in summer: photographed in the air. 



in, and lie quiescent during the winter. After 

 the spring thaws, if one rows over the shal- 

 lows near a lake shore, he may see the hiber- 

 nacula resting on the bottom, and as soon as 

 the sun's rays have warmed the water suf- 

 ficiently to allow growth, a few rise to the 

 surface, and all begin to send out roots from 

 the lower end, and stems form at the upper 



