REQUISITES OP PLANT GROWTH. 147 



numbers on the leaves of all plants. A 

 magnified portion of the leaf of the grape 

 is shown in figure 23. 



466. All plants come from seeds, in the 

 first place, and the farmer usually sows 



or plants the seeds of the plants he wishes Fi 23 

 to have ; but in some cases tubers or bulbs 

 are placed in the ground and new plants spring from 

 them. A tuber is a thickened portion of a stalk or stem 

 under ground, having buds or eyes, as the potato and the 

 artichoke. A bulb is a collection of fleshy scales formed 

 under ground by certain kinds of plants, as the tulip, the 

 onion, and the lily. 



467. Generally the seeds are sown where the plant is 

 to remain. But sometimes they are started in a carefully 

 prepared seed-bed, from which they are transplanted to 

 the field, where they can grow up to better advantage. 

 This is done to bring them forward earlier. 



468. For their complete development, all cultivated 

 plants must have a deep, mellow soil, and care enough 

 to prevent them from being injured by weeds or insects 

 while they are growing. The farmer must also attend to 

 fhe choice of seeds, taking only those which are good and 

 still have the power of germination, and must consider 

 how much seed he is to use, how he should prepare it, 

 the time and manner of sowing, and the depth to which 

 the seed should be covered. 



469. Choice of Seed. An imperfect seed may still be 

 capable of germination and may produce plants, which 

 appear to grow well at first, but such plants will have a 

 sickly and imperfect growth, especially at the time of 

 flowering, and they will produce little grain and that of 

 an inferior quality. 



