CHAPTER IV 



THE LEAF 



1. In chapter ii we spoke of leaves as being either 

 opposite or alternate, but in reality these terms 

 cover a number of slightly differing arrangements. 



Opposite leaves. When leaves are opposite, (i.e. 

 in pairs), the stem is usually, though by no means 

 always, four- sided, and each pair of leaves is then 

 at right angles to the next pair above and below. 

 This arrangement is called decussate. When how- 

 ever the leaves stand out to right and left, with, usually, 

 all the blades in one plane, as often happens with 

 branches that are horizontal, they are said to be 

 bifarious. 



Sometimes we find at a node not two but three 

 leaves, when they are said to be ternate ; and if 

 there are four or more we speak of them generally 

 as being whorled, or ' in whorls ' of four or more. 



Alternate leaves. In grasses and all plants of that 

 kind (e.g. all the cereal crop plants) and in some others 

 as HEDYCHIUM (wild Cardamom), and RAVENALA, the 

 * Traveller's Palm ', the leaves are in two rows one 

 on either side of the stem, and stand out to right and 

 left, but not all round it. This arrangement is termed 



