98 Thorny and Climbing Plants. (A walk) 



and when this support is found in the shape of a 

 convenient tree trunk little roots begin to grow all up 

 one side of this stem. These roots grow away from the 

 light, as all roots do (see Chapter V), hence they grow 

 towards the tree trunk, of which they take firm hold. 

 The ivy like any other plant draws all the food it wants 

 from the earth and air, so that it draws no nourishment 

 from the tree up which it grows. Nevertheless if it is 

 allowed to go on growing unchecked it will soon cover 

 the trunk and will seriously weaken the tree by keeping 

 light and air from it. A good landowner is therefore 

 careful that his trees are occasionally freed from all ivy. 

 A large number of climbing plants (including under 

 certain circumstances the ivy itself) have twining steins 

 which grow round and round any support they meet, 

 and so hold themselves upright. In other cases the leaf 

 stalk is twisted like a corkscrew and the plant climbs 

 by its help. To the first of these classes belong scarlet 

 runner beans and hops, to the second the clematis. 

 Other climbers again, as the bryony and the various 

 vetches, make use of long curly organs called tendrils 

 which are really different parts of the leaves or stem 

 converted specially for this purpose. 



PRACTICAL WORK. 



You will be taken for a walk and must notice in the woods and 

 hedgerows the various plants mentioned in this lesson. Notice the 

 conditions under which they grow. Collect any thorny, spiny, 

 prickly, or climbing plants that have not been used in your lesson 

 (e.g. mahonia, barberry, robinia, blackthorn, convolvulus) and take 

 them home. 



