6 OUTLINE OF STRUCTURAL BOTANY 
This tap root may continue as the principal axis, taking often the 
form which we see in the beet or carrot (Fig. 4), in which case it 
is said to be a fleshy root, or it may maintain a more slender form. 
In many cases roots become reservoirs of nutrient materials, in 
which cases they are thickened and fleshy, as in 
the case of the sweet potato, the peony and others 
(Fig. 5). These are tuberous roots, which differ 
from the tubers like the common potato in that 
this last uniformly bears buds or eyes, and is 
therefore a part of a modified stem. In the ma- 
jority of plants whose leaves are net-veined, 
branches diverge from the tap root which may 
equal or exceed it in size and importance and the 
root then divides like the branches of a tree, in 
which case it is said to be ramose. 
This is the form assumed by most. 
shrubs and trees and by a great num- 
ber of herbs. 
rot of Apion” ~—-« If we examine a young root more in 
detail we find that at its very extremity 
it is terminated by a little cap. This cap may be seen Fis. 6-Two 
plants of 
without the aid of a glass in the little thread hanging Lemna about 
three times 
from the body of the duckmeat, Lemna (Fig. 6), which enlscaee 
floats at the surface of the water. The of the oe 
cap varies in length and in comparative TD eee 
thickness, but is always present and is 19°t spay 
Mei 7 which is 
the advancing organ in the process of ord tee 
rrowth. Ab i c= ticeable in 
g ove the cap, with some ex pe gaat 
ceptions, appears a more or less ex- plant than 
tend . : E in most 
ended ring of fine hairs, the pilose _ others. 
portion of the root (Fig. 7). It is by way of 
these hairs and not by way of the cap that such 
nutritive material as is taken from the soil, the 
water or the air, through the root is introduced 
into the circulation of the plant. As the root 
Kia. Mouue ees in length these hairs disappear above 
Morning Glory. and new ones appear, maintaini » Ti i 
eer gg ea ppear, maintaining the ring in 
cotyledons or about a constant distance from the terminal cap. 
“seed leaves” is f . ; : 
aes the eehaatl Above the ring of hairs the root assumes a 
i lumule , s9TANeA aa : 
‘Along. the course Siooth appearance. In the case of the roots of 
of the branching net-veinec Tht ‘ Ss 1 ¥ ' . 
roots the “ pilose ed leaved plants the young rootlet ap 
portion” is shown. pears to enter the root by an opening, as there is 
