162 



INTRODUCTION TO BOTANY 



153. Rest period before germination. A few kinds of seeds 

 may sprout as soon as they are ripe ; most kinds need a period 

 of rest and comparative dryness before they will grow. The 



I 



FIG. 144. Seed and seedlings of morning-glory 



A, section of seed, showing cotyledons folded together and inclosed in endosperm ; 



B, seed germinating, the taproot descending and the cotyledons pushed up out of 

 the ground; C, seedling with cotyledons expanded, the plumule showing as a 

 bud at the junction of their leafstalks ; D, seedling further developed ; cot, coty- 

 ledons ; I, first ordinary leaf ; I', second ordinary leaf 



importance of drying seeds is well shown in the case of corn. 

 Kiln-dried corn has, in one instance, been shown to yield sixteen 

 bushels per acre more than air-dried seed of the same variety. 



