REINFORCED FRUITS, CONCLUDED 



285 



abortive ovules. In some oaks, the abortive ovules are near the 

 apex of the seed and in others near the base of it. 



334S. In studying the oak the collector will often find peculiar 

 swellings on the twigs and leaves. These are usually globular, and 

 the largest of them, which are sometimes called "oak apples," are 

 an inch in diameter. A cross-section shows a fibrous or rayed 

 structure. These objects are galls, and are produced by insects, 

 the grubs or larvse of which live in them. 



335. A hickory-nut is drawn, natural size, in 

 Fig. 291. The nut is enclosed in a husk, which 

 splits into four valves. We know that the edible 

 meat of the hickory-nut is the seed, and the bony 

 walls of the nut must be the pericarp, for the 

 hardened remains of the style are persistent at its 

 top. The fruit of the hickory is, therefore, dehis- 

 cent only to the pericarp. What 

 is the morphology of the husk? 



336. The black walnut and 

 the butternut are closely allied 

 to the hickory-nut, but the husk 

 is indehiscent. The pistillate 

 flowers of the butternut are 

 shown in Fig. 292. There are two 

 long stigmas exserted from a flask- 

 shaped body. There are eight 

 petal -like members upon this 

 body, constituting a perianth, four 

 their inside position, we may call 

 outer four sepals. It is the 

 which ripens into the husk of the butternut, and 



Fig. 291. 

 Hickory-nut. 



of which, from 

 petals and the 

 flask -like body 



