16 BOTANY 



rounded fleshy mass of the stem exposes much less 

 surface for evaporation than would the laminae of 

 ordinary leaves, and the plant is thus able to inhabit 

 very arid regions. 



A great contrast to the Cactus, with its pudding-like 

 stem, is the delicate Creeper that is not strong enough 

 to stand alone. Here the leaves, instead of being re- 

 duced, have additional work to do, for when a plant 

 economises in the tissue it puts into its stem, and has 

 a slender axis requiring support, it may call on its leaves 

 to assist it in attaching itself. The Sweet-pea does 

 this, and at the ends of its compound leaves several of 

 the leaflets are reduced and modified into tendrils, 

 which are sensitive and motile and cling to any support. 

 The well-known creeper, the Ampelopsis, is another 

 example of this, in which case the whole of one leaf 

 in each pair is modified to form several tendrils, each 

 ending in an adhesive disc. 



One of the strangest modifications of leaves is that 

 in connection with the capture of insect prey. The 

 Sundew (Drosera) with its red leaves covered with 

 sparkling tentacles, the sickly yellow leaves of the 

 Pinguicula, and the strange and elaborate Pitcher 

 plants of all sorts have modified and elaborated their 

 leaves to produce traps for the insects they capture 

 and use as food. 



Though the leaves naturally are supported by the 

 stem, there are not wanting cases where the leaves 

 have become the support of the whole plant, as, for 

 instance, the great Stag's-horn fern, which is attached to 

 tree trunks, and, with its large shield-like leaves, forms 

 a bracket which catches fragments of soil and holds 

 the water, forming a kind of flower-pot in which the 

 roots ramify. Even more specialised " flower-pots " are 



