80 



SEEDS AND SEEDLINGS 



a white oily mass directly under the seed coats. This mass is called the 

 endosperm. If it is tested with iodine, it will be found to contain starch ; 

 oil is also present in considerable quantity. Within the endosperm lies 

 the embryo, a thin, whitish structure. 



The Uses of Seeds. Not only does a seed serve to continue 

 a species of plant in a certain locality, but it serves to give the plant 

 a foothold in new places. This can be done, as we shall see later, 

 to a limited degree by cuttings, grafting, and in other ways, but the 

 usual way is by the production and planting of seeds. Seeds may 

 be blown by the wind or carried by animals, or by a hundred de- 

 vices work their way to pastures new, there to establish outposts 

 of their kind. 



Immense numbers of seeds may be produced by a single plant. 

 This may be of great economic importance. A single pea plant 

 may produce twenty pods, each containing from six to eight seeds. 

 This would mean the possibility of nearly twenty-five thousand 



plants produced from the 

 original parent by the end 

 of the second season and 

 the rapid production of a 

 source of food for man- 

 kind. A plant of Indian 

 corn may produce over 

 fifteen hundred grains of 

 corn. On the other hand, 

 many weeds produce seed 

 in still greater numbers. 

 A single capsule of Jimson 

 weed has been found to 

 hold over six hundred 

 seeds. A single milkweed 

 The thistle is even more 



Milkweed fruit, showing method of seed dispersal. 



may set free over two thousand seeds, 

 prolific. 



Some seeds, especially those of weeds, are able to withstand 

 great extremes of heat and cold and still to retain their ability to 

 germinate. Some have been known to retain their vitality for 

 over fifty years. In plants, the seeds of which show unusual 

 hardiness, it is found that the food supply is often so placed as 



