114 The Leaf 



at right angles to it (Fig. 57). Thus the leaves grow up 

 the stem in four vertical lines with every other leaf in 

 the same straight line. If the two lowest leaves face 

 north and south the two next ones will face east and 

 west, while the pair above them will be north and south 

 again. In this way each pair gets more light than it 

 would do if overshadowed by the next pair of leaves. 



Where leaves grow alternately you will find that if 

 you draw a line joining all the places where the leaves 

 grow from the stem this line forms a corkscrew, the 

 corkscrew being more or less drawn out according as 

 the leaves grow thinly or thickly on the stem. The 

 shape of leaves often seems particularly suited to the 

 way they are arranged. If they are very small, as in 

 the yew and box, they make up for this by growing 

 close together. Trees with large leaves, on the other 

 hand, like the lime and maple, have their nodes far 

 apart, and the leaves themselves are often, as in the 

 case of the horse-chestnut, cut up into leaflets in order 

 still further to prevent them from keeping the light and 

 air from each other. 



PRACTICAL WORK. 



1. Write down anything unusual you notice about the way the 

 leaves of the eucalyptus grow. What does this tell you about the 

 country from which it originally came ? 



2. You are given several leafy twigs. Fold a piece of paper in 

 columns headed Name, Arrangement of leaves, Internode, Leaf. 

 Now look at your twigs and in the case of each write down the name 

 of the twig, whether the leaves are opposite or alternate, the length 

 of each internode (in inches and tenths) and the length of a leaf from 

 one end to another. 



3. Taking each of the twigs with alternate leaves, draw on it 

 with a pen or compass point a line connecting the points of insertion 



