ROOTS. 



Boots. Although popularly so considered, it is by no means 

 the case that all parts of jilants which grow beneath the surface 

 of the ground are roots. There are many stems beneath the 

 surface and many roots above. Eoots have no leaves, and are 

 otherwise simpler than stems. They elongate by a rapid multi- 

 plication and growth of the cells a very short distance (perhaps 

 the one-sixteenth of an inch in case of Indian corn) back of the 

 extreme tip end. At such place, called "primary meristem," 

 the cells rajiidly increase by division, some of which continue to 

 remain small and keep on dividing. 



A portion of stem, on the other 



hand, usually produces leaves 

 buds, and when young elon- 

 gates b}' a multiplication and 

 growth of the cells for a con- 

 siderable portion of its length. 

 The tender, gro>\'ing tip of a 

 root is protected as it pushes 

 along through the soil by a 

 root-crq) consisting of some 

 older and harder cells. As 

 these cells wear off, others 

 crowd forward and take their 



Fig. 1.— Longitudinal section through the places. In grasseS the growth 

 apex of a root of Indian corn, half of ^vhich ^ c c 



represents the cells as empty; a. a. outer and » ,v ririnisrv rnnt i^ «nnn 

 older portion ot the root-cap; above this is 01 tue primar} root Is fcOOU 

 the vounger portion, just above which are , . i j ■ 



verj- small cells that divide and make new overtaken and IS scarcely dlS- 

 cells for increasing the length of the root 

 andreplenislungthe root-cap.-<Sachs.) tinfuishable from the SCCOnd- 



O 



aries or their branches. 



Eoots perforate the leaf-sheaths or rudimentary leaves and 

 spring freely from the nodes or joints of underground stems of 

 June grass, quack grass, and in some instances they grow from 

 the nodes or joints of the stems above grounfl, especially where 

 thev are moist and well shaded. All the secondary roots — branch 



