192 



APPLIED BIOLOGY 



the compound leaf of the pea and of many other members 

 of the bean family there is a tendril in place of the terminal 

 leaflet of the compound leaf (Fig. 58) . There are some plants 

 which have the tips of simple leaves serving as tendrils. 

 In some plants (common green brier or cat-brier) a pair of 

 tendrils are attached at the base of each petiole ; and these 

 are modified stipules of the leaf. It is evident that any 

 part of leaves (petiole, blade, or stipules) may be modified 



FIG. 57. Modified 

 leaf of a sundew. 

 The sticky bristles 

 catch insects. (From 

 Strasburger.) 



FIG. 58. Leaf of pea. Large 

 stipules (ri), leaflets of the 

 compound leaf (6), terminal 

 leaflets modified into tendrils 

 (r). 



to serve as tendrils. It has already ( 172) been pointed out 

 that some tendrils are modified branches. A comparison of 

 position and structure will usually make it easy to decide 

 whether particular tendrils are from leaves or branches of 

 stem. 



Leaves for Food-storage. It has already been stated that 

 the concentric layers of bulbs (onion, tulip, etc.) are the 

 bases of leaves thickened by food stored for use in the next 

 season's growth. The use of the food becomes evident if 

 one plants an onion or other bulb in a pot, for after a time 

 the layers become reduced to thin and dry sheets. The 

 thick cotyledons of bean, pea, acorn, etc., are also examples 

 of food-storage in leaf -like structures. 



Leaves as prickles occur in some plants. Examine branches 



