CHAPTER II 



THE DISTINCTION OF A FLOWERING PLANT 

 INTO ROOT AND SHOOT 



Everyone is familiar with the fact that ordinary flowering 

 plants possess roots, stems, leaves, and flowers. The roots of 

 a plant constitute its root-system, and are usually concealed 

 in the soil; whereas the stems, leaves, and- flowers of the 

 plant together compose the shoot-system, and are generally 

 visible and above ground. But stems and leaves are occasion- 

 ally embedded in the soil ; whilst roots may be found raised 

 above the ground on sub-aerial parts of the plant. Hence we 

 cannot define a root as being the subterranean part of the 

 plant, nor the shoot as being the sub-aerial portion. It will, 

 therefore, be well to consider first what we mean by the terms 

 ".root" and "shoot." For this purpose the seedling of a 

 bean may be examined. The seedling consists of a main 

 axis, which bears certain structures — the lateral members — 

 on its sides. The ascending portion of this axis is the stem, 

 which possesses the flattened leaves as its lateral members. 

 At the tip of the stem the leaves are crowded together to form 

 a bud. The main stem may also produce lateral stems — the 

 branches — which are like itself. The descending part of the 

 main axis of the seedling is the main root, which has no leaves, 

 and therefore, does not terminate in a bud.* The root does, 

 however, bear branches similar to itself which are called the 

 lateral roots. i 



Even inside the seed of the Bean, the young plant, or embryo, 

 displays this distinction into root and shoot. The bean-seed 

 (fig. i) is externally clothed by a shell-like seed-coat termed the 

 testa (ts). The testa has a minute pore ivi) at one end of the 

 scar (hi) on its side. The whole of the space enclosed within 



* The tip of the root is covered by a Httle cap termed the root-cap, which 

 can only be properly seen by the aid of a compound microscope. 



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