THE STEM AND THE LEAF 59 
going to outstrip the corn, but if they are kept down until the 
corn has begun to shade the ground well, there will be little 
further trouble from 
most weeds. If, how- 
ever, the corn is cut 
early for green fodder 
or for ensilage, a rank 
crop of weeds will 
spring up between 
the rows. So foxtail 
and other weeds be- 
gin to flourish among 
the stubble as soon 
as oats, wheat, or rye 
have been reaped. 
The stem, then, by 
lifting the leaves up 
into the sunlight and 
supporting them there 
in favorable positions 
(fig. 39), gives them 
a chance to do pho- 
tosynthetic work, so 
that the whole plant 
prospers. Even climb- 
ing plants like the 
English ivy (fig. 40), 
with stems that bend 
away from the light 
toward a supporting 
rock or tree trunk, 
turn their leaves to 
face the light. There 
are many plants — 
Fic. 40. An English ivy (Hedera) grown in 
front of a south window 
WW, the line of the window casing; all to the left 
of this is unlighted wall. The tips of the shoots (t) 
avoid the light; the young leaves (7) have assumed 
no definite position; the mature leaves are nearly 
at right angles to the light coming from the direc- 
tion of the arrow 
ereeping kinds, like white clover, and those with flattish clus- 
ters of leaves, like the dandelion — which flourish in places 
