SHOOTS 
59 
independent plants by the dying of the runners (see Figs. 
47, 48). 
45. The floating type. In this case the stems are sus- 
tained by water. Numerous illustrations can be found in 
small inland lakes and slow-moving streams (see Fig. 49). 
Beneath the water these stems often seem quite erect, but 
FIG. 49. A submerged plant (Ceratophyllum) with floating stems, showing the stem 
joints bearing finely divided leaves. 
when taken out they collapse, lacking the buoyant power 
of the water. Growing free and more or less upright in 
the water, they seem to have all the freedom of erect stems 
in displaying foliage leaves, and at the same time they 
are not called upon to build rigid structures. Economy 
of building material and entire freedom to display foliage 
would seem to be a happy combination for plants. It must 
be noticed, however, that another very important condition 
is introduced. To reach the leaf surfaces the light must 
pass through the water, and this diminishes its intensity so 
