THE ORGANIZATION OF THE PLANT 83 



the flowers of monocotyledons there are normally three parts 

 in each circle, or whorl, or if there are more than this, the num- 

 ber is some multiple of three. The iris has three sepals, three 

 petals, three stamens, 

 and a pistil composed 

 of three carpels; the 

 lily has three sepals, 

 three petals, six Sta- FIG. 73. Plans of three typical flowers 



meilS and a three- The ^ rst a monocotyledon, the other two repre- 

 senting four-parted and five-parted dicotyledons 



parted pistil. I he 



flowers of dicotyledons are usually distinguished from those 

 of monocotyledons by having four or five parts in each circle, 

 though they often exhibit a much wider range of variation. 



The fruit. The fruit results from the ripening of the pistil, 

 or carpels, often in conjunction with other parts of the flower. 

 Its development is one of the results of pollination. Flowers 

 that fail to secure pollination are usually cut off and fall from 

 the plant soon after blooming. There are many exceptions to 

 this rule, however. All seedless fruits, among which may be 

 mentioned navel oranges, seedless grapes, bananas, the currant 

 of commerce, pineapples, and seedless or coreless apples and 

 pears, must of course be produced without pollination. The 

 secondary effects of pollination and the resultant fertilization 

 are often far-reaching, and may extend not only to the ovary, 

 or carpel, but to the receptacle and other parts as well. Fruits 

 that develop as the result of incomplete pollination often lack 

 the flavor of the seeded forms, and by their incomplete develop- 

 ment indicate the fact that they have failed to receive sufficient 

 pollen. In a majority of fruits the pistil alone is represented, 

 as in peas, beans, plums, and tomatoes. In the apple, pear, and 

 similar fruits the core, only, represents the pistil, the fleshy 

 part being the receptacle that has grown up around it. 



The fleshy part of the strawberry is also a receptacle, and 

 all the seedlike parts upon it are the remains of tiny pistils, 



