16 



THE PRODUCTION OF SEEDS 



The young plant breaks through the seed-coat and grows upward. 

 At about the same time, three or more roots in the grasses break 

 through and grow downward (Fig. 5). For a few days, the young 

 plant and roots depend on the seed for food. When the plant has 

 reached sunlight with its leaves, a new set of true roots have made 

 their appearance just below the soil surface, and the plant is no 

 longer dependent on the seed for maintenance. When the soil condi- 

 tions are good, the plant is quickly established and only a small 



Fia. 5. Wheat grain in three stages of germination, on the first, second and third days 

 after being placed in germinator (compare with tig. o). 



proportion of the stored food is actually required. When soil condi- 

 tions are poor, the plant may draw on the seed for a long time. The 

 seed alone will maintain the plant for two weeks. Large plump seed 

 is probably more important when conditions are unfavorable, than 

 when conditions are such that the plant can quickly establish on its 

 own roots. 



Large and Small Seeds. Examine a handful of wheat or corn, 

 as harvested, and great variation in size of seed will be noted. In 

 some cases, a part of the seeds will be very much shrunken. The 

 comparative merits of large and small seeds for planting are often 



