PLANT LIFE. 49 



the embryo itself we can usually distinguish one or two 

 seed leaves, the beginnings of the next leaves (plu- 

 mule), and the radicle (the part 

 that forms the stem below the 

 seed leaves and the roots). d - 



Germination. When the 



seed is placed where the condi- *^ &^ * 



tions of warmth and moisture 

 are favorable it absorbs water, 

 swells and often bursts its coat. 

 The radicle emerges and turns SEED OF BEAN. 



downward. The Seed-leaveS a, seed coat; &, cotyledon; c, 



may either remain underground SSS^Sfe&f" left 

 in the old seed coat while the 



plumule pulls out and pushes up to the air as in the 

 pea, or the whole seed may emerge from the ground, 

 the seed-leaves opening out and turning green and be- 

 ginning to manufacture food as in the bean, cucumber, 

 cotton, etc. The first few leaves after the seed-leaves 

 are in nearly all cases less complex than the latter ones. 

 Thus the clover leaf that follows the seed-leaves has 

 but one leaflet instead of three. 



Length of Life. After a certain length of time we 

 find that the production of flowers begins. For many 

 plants this terminates the period of growth, death en- 

 suing after the seeds are ripened, but for many others 

 the plant continues to grow, producing flowers and 

 seeds at yearly intervals. From germination of seed 

 until death of the mature plant, may be only six weeks 

 for some desert plants, while many trees do not begin 

 to flower until many years old and live hundreds of 

 years. 



Reproduction of Plants. As a rule most plants are 

 not solely dependent upon seed production for their 

 reproduction, or at least other methods of multiplica- 

 tion can be applied even when they do not occur nat- 

 urally. Thus some plants give rise to new ones at 

 various points on their roots as in the suckers of plums, 

 others have root-stalks (underground stems), which 



