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TEXTBOOK OF BOTANY 



and the primary leaf, push their way out through the surrounding 

 tissues. First to break out, usually, is the root. As soon as its tip 

 is free, it turns downward and grows into the soil. Next the primary 

 leaf pushes out its tip ; it grows forward beneath the parent plant until 

 it reaches the .notch at the growing point ; then it turns upward and 

 forms a flat green blade, which is much simpler in outline than are 

 the blades of the leaves formed later. 



Thus far the embryo has remained connected with the parent plant 

 by means of the foot, and dependent upon the parent for food ; but 



FIG. 58. A, the young asexual plant of a fern still attached to the 

 sexual plant ; the primary leaf and the primary root are both fully formed. 

 B, a portion of the young asexual plant, removed from the sexual plant 

 and considerably enlarged; a, the foot, by which the asexual plant is at- 

 tached to the sexual plant ; b, the young stem ; c, the base of the primary 

 leaf ; d, the upper part of the primary root. 



now, having a root pushing into the soil and a leaf exposed to the air 

 the young plant can obtain or manufacture all its food. The sexual 

 plant by this time has given up most of its available food ; it withers 

 and dies, but what is left of it remains for a time attached to the young 

 asexual plant.- The stem of the asexual plant is the last of the four 

 embryonic parts to develop. For some time it is merely a bud-like 

 swelling at the base of the leaf; but after the primary root and the 

 primary leaf have begun to supply food for the plant, this bud grows 



