PLANT SOCIETIES 321 
narrowness of the division permits plenty of light to 
penetrate to the plant’s lower leaves. It is also, doubt- 
less, much easier for leaves like those of the yarrow, the 
dog fennel, the tansy, the carrot, and their like, to with- 
stand the action of 
severe winds, to 
which they are often 
exposed, than it 
would be for leaves 
like those of the jack- 
in-the-pulpit (see 
Frontispiece), the 
trilliums, the lily-of- 
the-valley, and simi- 
lar leaves. 
393. Transition of 
a Plant from Shade 
Conditions to Sun ~ 
Conditions. — It is 
characteristic of 
many kinds of forest 
trees that the young 
seedlings are much 
more tolerant of 
dense shade than the Fie. 227. I, a Shade-Plant (Clintonia) ; II, a Sun- 
Plant, Dog Fennel (Maruta). 
adult trees are. 
Sometimes their seeds will hardly germinate at all unless 
thoroughly shaded, and the young trees for the first few 
years flourish best in the shade. Afterwards most trees 
need a good deal of sunlight, but they may live long 
with a scanty supply of light. The red spruce sometimes 
