FRUITS AND THEIR USES 121 



Figs. 3 and 4. The Bean. This is a typical dry fruit with several seeds, 

 which opens to scatter them. 



It consists of the fully developed pistil, the bulk being the greatly enlarged 

 ovary, with the stigma reduced to the tapering tip, and the stigma usually 

 fallen off in a fully matured pod. 



The "string" which we remove in preparing for food, is a duct bundle that 

 brought nourishment to the ovules and reached each by way of the hilum. 



The point of attachment to the pod is the placenta, (P) and shows in both 

 drawings. 



The pod is the thickened ovary wall (O), and at its base the shriveled calyx 

 is sometimes found. 



The cross section shows a seed cut across, displaying the seed coats (C), 

 and the two cotyledons (Cot.). 



relatively large amount of room. Evidently, then, the seeds must 

 be scattered if they are to survive, and usually those plants pro- 

 ducing most seeds or needing most room best attend to this matter 

 of seed dispersal. There is scarcely a more interesting chapter in 

 biology than this one which deals with the wonderful adaptations 

 by which seeds, though having no power of locomotion, still manage 

 to transport themselves long distances and in great numbers. 

 Plants use the wind, water, animals, and various mechanical 

 schemes to scatter their seeds. Sometimes it is the seed by itself 

 which is transported, sometimes the whole fruit, but the end is the 

 same, to get a new place where there shall be space, food, light, 

 and moisture for the development of the waiting embryo. 



Adaptation for Wind Dispersal. Adaptations for wind dispersal 

 are found in the tufts of down on thistle and dandelion fruits and 

 milkweed seed, in the wings on the fruits of elm, ash, or maple, or 

 on the seeds of the catalpa or pine. 



Adaptations for Dispersal by Animals. Burs and hooks, as in 

 burdock and " pitchforks," enable the fruits to steal rides on 

 animals and man, and get themselves picked or shaken off at great 

 distances. The delicious flesh of peach or apple, grape or berry is 

 merely a sort of bribe to reward some animal for carrying off the 

 fruit. The seeds of all such are indigestible and so are carried far 

 from the parent plant. It is noteworthy that unripe fruits are usu- 

 ally poisonous or bad tasting. Thus they are not eaten before 

 the seed is ready for dispersal. 



