FORM AND STRUCTURE 



Head, is like a spike except that the central axis is so short 



that the flowers form a compact cluster. 

 Strobile, is a compact cluster with large scales concealing the 



flowers. 



FRUIT. 



The Fruit consists essentially of the ripened pistil. After 

 the ovaries have been fertilized the ovary is called a Peri- 

 carp. The following kinds of fruits are those most frequently 

 borne by trees and are the products of a single flower : 



Akene, is a one-seeded, dry, hard, seed-like fruit. 



Samara, resembles an akene except that it has a wing-like 

 appendage. The Ash, the Elm and the Maple produce 

 samaras. 



Glans or Nut, is a fruit with a thick hard pericarp, enclosed 

 more or less in an involucre. The acorn is a nut. 



Drupe, is often called a stone fruit. In it the wall of the 

 pericarp is differentiated into three divisions — the outer 

 or skin called exocarp, middle or fleshy portion called 

 mesocarp, the inner wall enveloping the seed called endo- 

 carp. A cherry is a drupe. 



Tryma, is a fruit structurally resembling the drupe, but the 

 mesocarp is harder, more fibrous, and the outer husk ulti- 

 mately splits open and comes off. A hickory nut is an 

 example. 



Berry, has a thin rind and all the rest of the pericarp is suc- 

 culent. Berries may be one or many-celled. Grape and 

 currant are examples. 



Pome, is a fleshy fruit, the chief bulk of which consists of an 

 adherent fleshy calyx. The apple is a pome. 



Legume, is a dry one-carpelled fruit or pod that splits open 

 front and back. The fruit of the I>ocust is a legume. 



Capsule, consists of two or more united pistils which open 

 and allow the seeds to escape. 



Fruits that are the product of one flower but of more than 

 one pistil are called Aggregated Fruits. Raspberry is an 

 example. Fruits that are the products of flower clusters 

 instead of single flowers are called Multiple Fruits. 



513 



