CHAPTER XLV. 



SEEDLINGS. 



582. An interesting period in the life of plants is during germination, when 

 the embryo plant comes out of the seed and lifts its leaves and stem above the 

 ground. In the germinating corn plant the young leaves are wrapped around 

 one another and enclose the stem, form- 

 ing a long, slender, pointed sheath, if it 



may be so called. As this pushes its way 

 through the soil it stands erect, with the 

 pointed end uppermost. Because of its 

 form and the compactness with which the 

 leaves are wrapped together, it easily 

 wedges its way through the soil, with no 

 harm to the tender leaves and stem. 



583. The pea seedling comes out of 

 the ground in a very different way. By 

 the swelling of the two thick cotyledons 

 the outer coat of the' seed is cast partly 

 off, the root emerges on one side, and the 

 short stem is curved between 



the cotyledons in the form of 

 an arch. The cotyledons re- 

 main in the soil, while the 

 arched stem, as it elongates, 

 pushes its way 

 through the soil. 

 The leaves of 



Fig. 401. 



How the garden bean comes out of the ground. First the looped hypocotyl, then the 

 cotyledons pulled out, next casting off the seed coat, last the plant erect, bearing thick 

 cotyledons, the expanding leaves, and the plumule between them. 



307 



