The aerial roots of the English Ivy answer another purpose than that of giving nourishment to the plant.  They are used to support it in climbing.  These are an example of secondary roots, which are roots springing laterally from any part of the stem.  The Sweet Potato has both fleshy and fibrous roots and forms secondary roots of both kinds every year.[1] Some of the seedlings will probably show the root-hairs to the naked eye.  These will be noticed hereafter.

[Footnote 1:  Gray’s Lessons, p. 35, Fig. 86.]

[Illustration:  FIG. 11.—­1.  Tap-root. 2.  Multiple root of Pumpkin. 3.  Napiform root of Turnip. 4.  Spindle-shaped root of Radish. 5.  Conical root of Carrot. 6.  Aerial roots of Ivy.]

It is my experience that pupils always like classifying things under different heads, and it is a good exercise.  The following table may be made of the roots they have studied, adding other examples.  Dr. Gray says that ordinary roots may be roughly classed into fibrous and fleshy.[1] Thome classes them as woody and fleshy.[2]

[Footnote 1:  Gray’s Lessons, p. 34.]

[Footnote 2:  Text-book of Structural and Physiological Botany.  Otto Thome.  Translated and edited by Alfred W. Bennett, New York.  John Wiley and Sons. 1877.  Page 75.]

ROOTS.
|
------------------------------------------
|                                        |
Primary.                             Secondary.
|                                        |
--------------------------------                |
|                              |                |
Fibrous.                     Fleshy.         Roots of cuttings
|                                            Aerial roots.
-------------------                           Sweet potatoes.[3]
|                 |
Simple.      Multiple.     Simple.

Morning Glory.   Pumpkin         Carrot. 
Sunflower.                       Radish. 
Pea.                             Turnip. 
Bean.                            Beet. 
Corn.            Corn.

[Footnote 3:  The Irish potato will very likely be mentioned as an example of a fleshy root.  The teacher can say that this will be explained later.]

2. Fleshy Roots.—­The scholars are already familiar with the storing of food for the seedling in or around the cotyledons, and will readily understand that these roots are storehouses of food for the plant.  The Turnip, Carrot, and Beet are biennials; that is, their growth is continued through two seasons.  In the first year, they make a vigorous growth of leaves alone, and the surplus food is carried to the root in the form of a syrup, and there stored, having been changed into starch, or something very similar.  At the end of the first season, the root is filled with food, prepared for the next year, so that the plant can live on its reserve fund and devote its whole attention to flowering.  These roots are often good food for animals.