46 THE STORY OF THE PLANTS. 



ing plants, for example, the leaves are usually 

 opposite, so as to clutch more readily, and they 

 are almost always more or less heart-shaped at 

 the base, as in convolvulus and black briony. 

 The leaves of forest trees, on the other hand, 

 tend to be what is known as ovate in shape, like 

 the beech and the poplar ; while those of the 

 lime are a little one-sided, in order that each leaf 

 may not overshadow and rob its neighbour. This 

 one-sidedness is even more markedly seen in the 

 hot-house begonias. Some leaves, again, are mi- 

 nutely subdivided into leaflets twice or three 

 times over; such leaves are said to be doubly or 

 trebly compound. But if you study plants as 

 they grow (and this book is written in the hope 

 that it may induce you to do so), you will gener- 

 ally be able to see that the shapes and peculiari- 

 ties of leaves have some obvious reference to 

 their place in the world, and their habits and 

 manners. 



I have spoken so far mainly of quite central 

 and typical leaves, which are arranged with a 

 single view to the need for feeding. Rut plants 

 are exposed to many dangers in life besides the 

 danger of starvation, and they guard in various 

 ways against all these dangers. One very ob- 

 vious one is the danger of being devoured by 

 grazing animals, and, to protect themselves 

 against it, many plants produce leaves which are 

 prickly, or stinging, or otherwise unpleasant. 

 The common holly is a familiar instance. In 

 this case the ribs are prolonged into stiff and 

 prickly points, which wound the tender noses of 

 donkeys or cattle. We can easily see how such a 

 protection could be acquired by the holly-bush 



