CHAPTER XIII. THE FRUIT AND SEED. 



of the Ash, Fig. 316 that of the Elm, and Fig. 306 the double 

 samara of the Maple. 



(5) The G/a/is, or nut. This is a fruit, like that of the Oak 

 or Hazel, with a thick, hard pericarp, enclosed, or partly so. in 

 an involucre, Fig. 317. In the case of the Acorn, the involucre 

 consists of a cup-shaped expansion of the axis covered by 

 closely imbricated scales, and is called the cupule. 



(6) The Cremocarp. This is the peculiar double fruit pro- 

 duced by umbelliferous plants. Each mericarp, or half of the 

 fruit, structurally resembles an inferior akene, but is longitudi- 

 nally ribbed, and there are usually oil tubes between the ribs. 

 Fig. 318 represents the cremocarp of Fennel. By some botanists 

 it is regarded as a variety of capsule. 



Fig. 321. 



Fie. 322. 



Fig. 323. 



Fig. 321. — Tryma of Juglans regia, the English Walnut, with portion of sarcocarp 

 removed. 



Fig. 322. — Fruit of Lemon, cut transversely, illustrating a hesperidium fruit. 

 Fig. 323. — Cucumber, cut transversely, illustrating pepo fruit. 



(7) The Drupe. This is a one-carpelled fruit like that of 

 the Plum, Cherry and Peach, and is often called a stone fruit. In 

 it the wall of the pericarp is differentiated into three portions, 

 the outer or " skin," called the exocarp, the middle or succulent 

 portion the tnesocarp, and the inner portion or hard wall envelop- 

 in/ the seed, the endocarp or putamen. Fig. 319 represents the 

 drupe of the Cherry in longitudinal section. 



(8) The Tryma. This is a fruit structurally resembling the 

 drupe, but the mesocarp is harder, more fibrous, the outer husk 

 in most cases ultimately dehiscent, and the cavity containing the 

 seed is usually more or less distinctly two-celled. The fruits of 

 the Hickory, Walnut and Pecan are illustrations. See Fig. 321. 



