BOTANY FOR BEGINNERS 



CHAP. 



few holes in the soil. Plant the mustard seedlings, firmly pressing the 

 soil to the roots. Water the soil ,and place the pot on a window sill. 

 Examine every day, and notice that ther'apex of the stem gives off 

 new leaves, and that these new leaves are very different from the seed 

 leaves. 



EXPT. 6. Take some of the seeds of the Indian Corn used in 

 Experiment 3, and, as before, plant them in a box or plant pot, and 

 notice that 



(i) The plumule is the first part to appear above the soil, and its tip 

 is surrounded by the cotyledon. 



(ii) Carefully remove a plant from the soil ; the primary root or radicle 

 is very short, and from it are produced a very large number of 

 adventitious roots. 



FIG. 9. A Maize seedling, showing 

 roots and leaves. 



FIG. 10. Adventitious roots of a 

 Grass. 



Adventitious roots are those roots which are not produced in 

 regular order. Roots are also given off from the plumule just 

 above the cotyledon. The difference between primary, secondary, 

 and adventitious roots is well seen in the mustard and in the 

 Indian corn. Primary roots are always formed by the elonga- 

 tion of the radicle ; the secondary roots grow from the radicle, 

 in regular order ; but adventitious roots are produced from the 

 stem, or some part of the plant other than the primary root. 



