334 



FRUITS AND SEEDS 



F. Self-planting Fruits. — Certain fruits have the in- 

 teresting habit of planting themselves. The fruit of the 



peanut, which is a pod, 

 is an example of this. 

 The flowers of the peanut 

 plant are borne under the 

 leaves, near the ground. 

 After fertilization, the 

 flower stalks begin to grow 

 again, and downwards. 

 They thrust the young 

 pods beneath the soil, and 

 there the seeds ripen and 

 germinate. (See Figure 



*47-) 



The fruit of the porcu- 

 pine grass (Stipa spartea) 

 plants itself after it is 



Fig. X47. - Peanut plant showing the down- ated from its nt 



ward growing stems which thrust the pods r r 



when young beneath the soil. The roots It bears a long, Spirally- 



bear numerous tubercles. See page 377- twisted appendage, the 



awn. (See Figure 148.) This awn absorbs moisture at 

 different rates in its different parts. This causes it to twist 

 and untwist as atmospheric conditions change. The twist- 

 ing process tends to drive the heavier, sharp-pointed part 

 of the fruit down into the soil, and the upward pointing 

 bristles prevent it from being withdrawn when untwisting 

 occurs. These fruits bore their way through paper or cloth. 

 They will make their own way out of a pocket or envelope 

 in which they may be placed, and they have even been 

 found deep in the flesh of grazing animals. The fruit of 

 the stork's-bill (Erodium) has similar powers. 



