LEAVES OF PECULIAR FORMS AND USES. 107 



plants, and those which could develop insect-catching powers 

 would stand a far better chance to exist as air-plants or in the 

 thin, watery soil of bogs than plants which had acquired no 

 such resources. 



132. Leaf Disguises. — Leaves in the form of spines, of 

 tendrils, and of pitchers have been referred to, and it is not 

 uncommon to find leaves in other forms, hardly recognizable, 

 except by the botanist, as leaves. The student has learned 

 to consider bud-scales and the scales on root-stalks and bulbs 

 as leaves (§§ 101, 106). Storage-leaves above ground are 

 common in desert regions and not very unusual in plants of 

 temperate climates. The common century plant is an excel- 

 lent example of food-storage in the leaf, and the aloes, eche- 

 verias and house-leeks are other instances. There is little 

 difficulty in recognizing dwarfed leaves in the little bracts 

 which occur in many kinds of flower-cluster (Fig. 105). 

 Scale-like leaves are found on some stems above ground, as in 

 the case of the curious Indian pipe (Fig. 100), and on young 

 shoots of asparagus in early spring. Leaves forming the 

 parts of the flower will be studied in a later chapter (XVI). 

 The leaf sometimes, though rarely, appears as a wing to aid 

 in the transportation of the fruit, as in the linden (Fig. 173). 



