STRUCTURE AND WORK OF PLANTS 



23 



the ovule. While still within the ovule wall, the root, stem, 

 and leaves of the new plant are formed. The ovule wall be- 

 comes hard, and, with the new plant within it and with more 

 or less stored food, constitutes the seed. During the time when 

 the seeds are developing the ovary also may grow (Fig. 15). 



FIG. 17. Growth of new plants from seeds of the beech tree 



At the left are very young seedlings, one of which shows only the seed leaves 



(cotyledons) , the other showing between the seed leaves a slender stalk which is 



the beginning of the stem. In the plants at the right the seed leaves still are 



present, but other leaves and the stems have grown considerably 



23. Flowers and seeds: the fruit, and seed germination. 

 When the seeds are ripe they may fall from the ovary, or 

 with one or more of the structures about them they may com- 

 pose the so-called fruit. 



Under favorable conditions the young plant within the 

 seed bursts the seed coat and begins its growth. It pushes 

 out its roots, stem, and leaves, and soon assumes the ap- 

 pearance of the kind of plant that formed it (Figs. 16 and 17). 



Details regarding the parts of the plant and the work they 

 do will be treated in later chapters. 



