96 THE FRUIT : DISPERSAL OF SEEDS 



the receptacle, while the ripened gynaecium of the apple is its 

 ' core ' (see p. 404). 



The tomato, vegetable marrow, and cucumber are true fruits, 

 that is, they are the products of the gynaecium only, but are 

 nevertheless popularly designated ' vegetables.' 



The term pseudocarp, or '■spurious fruit,' is frequently used 

 for structures, such as the apple, strawberry, fig, and mulberry, 

 produced from a flower or inflorescence, but which includes 

 something more than the gynsecia and their contents. 



2. A complete satisfactory classification and nomenclature of 

 fruits is still wanting : they may, however, be divided into four 

 groups as indicated below, according to the texture of the 

 pericarp and the manner in which the seeds are set free from 

 the fruit. 



I. Indehiscent Dry Fruits. 



In these the pericarp is dry and woody or leathery in texture, 

 and does not split or open along any definite lines. The seeds 

 are set free by the decay of the pericarp. As the necessary 

 protection for the embryo and its store of food against adverse 

 climatic influences and the attacks of animals, is afforded by 

 tlie strong pericarp, the testa of the seed itself is usually thin 

 in these fruits. 



The following are the commonest forms of fruits of this 

 class : — 



(i) The nut is a one-seeded fruit, with a woody pericarp ; 

 it is developed from an inferior syncarpous ovary. Examples are 

 hazel-nut, beech-nut, acorn and Spanish chestnut. 



The fruit of the horse-chestnut is not a nut, but a berry-like 

 capsule. 



The fruit of the Compositae (Figs. 147, 148) is termed a cypsela, 

 and is a form of nut developed from a syncarpous inferior ovary 

 of two carpels. Its pericarp is thin, and contains within it only 

 one seed ; the calyx is frequently present as a pappus. 



