13, 14.] THE STAGES OF PLANT LIFE. 15 



and fruit, and having more points of resemblance than 

 of difference throughout. Thus, the genus Clover (Tri- 

 folium) includes many species, as the White Clover 

 (T. repens), the Red Clover (T. pratense), the Buffalo 

 Clover (T. reflexum), etc., agreeing in floral structure 

 and general aspect so obviously that the most hasty 

 observer would notice their relationship. So in the 

 genus Pinus, no one would hesitate to include the 

 Wl^ite Pine, the Pitch Pine, the Long-leafed Pine 

 (P. strobus, P. rigida, and P. palustris), any more than 

 we would fail to observe their differences. 



30. Thus individuals are grouped into species, and 

 species are associated into genera. These groups con- 

 stitute the bases of all the systems of classification in 

 use, whether by artificial or natural methods. 



CHAPTER III. 



THE STAGES OF PLANT LIFE. 



31. In its earliest stage of life, the plant is an 

 embryo sleeping in the seed. It then consists of two 

 parts, the radicle or rootlet, and the plumule. Both 

 may be seen in the Pea, Bean, or Acorn. Besides the 

 embryo, the seed contains also its food in some form, 

 provided for its first nourishment. 



32. When placed just beneath the surface of the 

 soil, it absorbs moisture, which, with the genial warmth 

 of Spring, awakens the embryo, and it begins to feed 

 and grow. The radicle protrudes (Fig. 2, r), turns 

 downward, seeking the dark damp earth, avoiding the 

 air and light, and forms the root or descending axis. 

 The plumule, taking the opposite direction (Fig. 3, p), 



