FRUITS AND SEEDS 111 



from their large size, inferior ovary and thick skin are usually 

 referred to by the special name of " pepo." 



The dry fruits are those in which the fruit is a dry structure, 

 usually known as a pod. If this pod opens and releases the seed, 

 it is dehiscent, but if it does not open until forced open by the 

 germinating seed, it is indehiscent. The term pod., or capsule, 

 is used to indicate any dehiscent fruit, regardless of the number 

 of carpels involved in its formation. The term legume applies 

 to the elongated, one-carpelled pods of many members of the 

 family Leguminosw, such as the pea and bean. 



The most important of the indehiscent fruits (Fig. 80) are: 



FIG. 80. -Types of indehiscent fruits; (a) achene, (6) caryopsis, (c) samara, (d) nut. 



(a) The achene or akene, which is a small dry fruit con- 

 taining a single free pod, such as is produced by the buttercup 

 (Fig. 80, a). 



The so-called seeds of the strawberry are achene fruits resting 

 on a fleshy torus, each achene being derived from a single pistil. 



(&) The samara or key is a fruit a part of which is developed 

 into a thin flat wing, as in the case of the maple (Fig. 80. c), ash 

 and elm. 



(c) The caryopsis or grain is a fruit in which the mature 

 ovary has united with the seed coats, as in the case of many of 

 the grains, such as corn and wheat (Fig. 80, 6). These fruits are 



