80 



SEEDS AND FRUITS 



In developing from a single flower but involving a number of 

 pistils, the fruits of the Strawberry and Blackberry are similar 

 and are classed as aggregate fruits. 



Pineapple Type. In the formation of the Pineapple a num- 

 ber of flowers are involved, each of which consists of a small 

 pistil surrounded by large scales and is borne in the axil of a modi- 

 fied leaf. Each ovary with 

 its scales and modified leaf 

 becomes fleshy to form a 

 single fruit. The entire fruit 

 of the Pineapple consists of a 

 number of these single fruits 

 closely packed together on 

 an axis which forms the core 

 of the Pineapple. Since a 

 number of flowers are in- 

 volved, fruits of this type 

 are known as multiple fruits. 

 (Fig. 81.} 



Nut Type. In the nut 

 type of fruit, the ovary is 

 hard and is generally partly 

 or entirely covered by a 

 husk formed by the perianth 

 or by bracts which grow up 

 from the receptacle. (Fig. 

 82.} Notice the develop- 

 ment of the Acorn shown in 

 Figure 83. 



Some Other Familiar Types of Fruits. In many small fruits 

 the ovaries become dry and often hard as the fruit matures. 

 They are the kind which when small and one-seeded are often 

 called seeds. It has been mentioned that the akenes of the Buck- 

 wheat and the cariopsis of the Grasses are fruits with hard ovary 

 walls. In the Clovers, Alfalfa, and Beans the ovary wall becomes 

 dry and hard when mature, forming the structure known as the 

 pod or legume. (Fig. 84.} Many of the so-called weed seeds are 

 dry ovaries. In many cases, however, other structures are joined 

 with the hardened ovary in the formation of the fruit. In the 

 Dandelion and many other plants of the Composite type, the 



FIG. 81. Pineapple. After Koch. 



