LESSON 5.] MORPHOLOGY OF ROOTS. 29 



for the young student to learn them by rote. The student should 

 rather consider the connection between one form and another ; and 

 notice how the one simple plan of the plant, as it has already been 

 illustrated, is worked out in the greatest variety of ways, through the 

 manifold diversity of forms which each of its three organs of vege- 

 tation root, stem, and leaf is made to assume. 



63. This we are now ready to do. That is, having obtained a 

 g neral idea of vegetation, by tracing the plant from the seed and 

 the bud into the herb, shrub, or tree, we proceed to contemplate the 

 principal forms under which these three organs occur in different 

 plants, or in different parts of the same plant ; or, in other words, to 

 study the morphology of the root, stem, and leaves. 



64. Of these three organs, the root is the simplest and the least 

 varied in its modifications. Still it exhibits some widely different 

 kinds. Going back to the beginning, we commence with 



65. The simple Primary Root, which most plants send down from 

 the root-end of the embryo as it grows from the seed ; as we have 

 seen in the Maple (Fig 5 - 7), Morning-Glory (Fig. 8 and 28), 

 Beech (Fig. 14, 15), Oak and Buckeye (Fig. 22-24), &c. This, 

 if it goes on to grow, makes a main or tap root, from which side- 

 branches here and there proceed. Some plants keep this main root 

 throughout their whole life, and send off only small side branches ; 

 as in the Carrot (Fig. 58) and Radish (Fig. 5*9) : and in some trees, 

 like the Oak, it takes the lead of the side-branches for many years, 

 unless accidentally injured, as a strong tap-root. But commonly 

 the main root divides off very soon, and is lost in the branches. 

 We have already seen, also, that there may be at the beginning 



66. Multiple Primary Roots, We have noticed them in the Pump- 

 kin (Fig. 10), in the Pea (Fig. 20), and in Indian Corn (Fig. 42). 

 That is, several roots have started all at once, or nearly so, from the 

 seedling stem, and formed a bundle or cluster (a fascicled root, as 

 it is called), in place of one main root. The Bean, as we observe 

 in Fig. 18, begins with a main root , but some of its branches soon 

 overtake it, and a cluster of roots is formed. 



67. Absorption of Moisture by Roots, The branches of roots as they 

 grow commonly branch again and again, into smaller roots or rootlets ; 

 in this way very much increasing the surface by which the plant 

 connects itself with the earth, and absorbs moisture from it. The 

 whole surface of the root absorbs, so long as it is fresh and new ; 

 and the newer the roots and rootlets are, the more freely do they 



3* 



