THE NATURE OF SEEDS 335 



G. Seedless Fruits. — In some plants fertilization is not 

 necessary for the production of fruit. You have noted 

 this in the case of fig, in which not 

 even pollination is necessary. (See 

 page 318.) Usually fruits so produced 

 are said to be seedless, though the rudi- 

 ments of seeds are commonly found in them. 

 Seedle'ss oranges are familiar. The cultivated 

 banana never produces seeds. Certain varieties 

 of grapes, apples, pears, and gooseberries are also 

 seedless. The seedless condition of the fruit may 

 be only an occasional condition, as in the seedless 

 persimmons found growing wild. The seedless orange 

 and other varieties of cultivated seedless plants can 

 be propagated, of course, only by means of cuttings 

 from the parent plant. Seedless varieties have, in 

 some cases, been produced by selecting forms with 

 few and small seeds, and using in propagation only 

 those forms showing the greatest tendency toward 

 seedlessness. 



There is a parasitic flowering plant (Balanopfwra) 

 which, without either pollination or fertilization, 

 produces fruits containing seeds which germinate. 



67. The Nature of Seeds. — As previously stated 



(see page 267), the seed is one of the most complex 



of plant organs, and its nature can- 



FiG. 148. — Mature fruit of not be fully comprehended until 



trrtteTsS those structures of lower plants are 



twisted awn and the upward studied which indicate its cvolution. 



pointing bristles behind the j^. jg ^^ enlarged and matured ovule. 



lower apex of the fruit. ° . 



See context. After fertilization, the ovule, con- 



