LESSONS IN BOTANY. 187 



portions in different plants ; but in every case they serve to 

 strengthen the plant structure and as a means for conducting 

 liquids from roots to leaves. 



The fundamental system includes all the tissues not found in 

 the other systems, being made up mainly of parenchyma, thick 

 angled tissue, milk tissue, etc. 



An examination of a green stem of Indian corn will give one a 

 good idea of the vascular bundles and the parenchyma surround- 

 ing them. An examination of the leaf stalk of the squash shows 

 whitish bands extending from end to end just beneath the epi- 

 dermis. They are masses of thick angled tissue, which may be 

 torn out, when the stalk becomes weak and flexible. The large 

 pores seen in cross sections of oak, ash and other woods are 

 pitted vessels. 



Plants are made up of the various tissues and systems men- 

 tioned. The lower plants consist mainly of parenchyma, while 

 all three systems unite to form the bodies of the higher plants. 

 Such plants are made up of stem, leaves and roots. 



The typical stem is illustrated in the trunk of a tree or the 

 body of an upright plant, bearing branches and leaves and sup- 

 ported by roots; but it also appears in many other forms : First, 

 as runners, which are slender and weak, creeping along the ground 

 and bearing stunted leaves or bracts, as in the case of straw- 

 berries. Second, rootstocks, scale-bearing underground stems, 

 as in the case of ferns. Third, tubers, scale-bearing, thickened 

 and subterranean, as the potato. Fourth, the cormb, a thick, 

 solid body with thin leaves, subterranean, as the Indian turnip. 

 Fifth, bulbs, small bodies covered by the thickened bases of 

 leaves, as the onion. Sixth, tendrils, slender branches usually 

 destitute of leaves. Seventh, thorns, short, thick, pointed 

 branches without leaves. 



The leaves are broad, flat expansions of chlorophyll-bearing 

 tissue, supported by a framework of fibrous tissue. They may 

 be reduced to bracts, or scales, which have but little chlorophyll, 

 or, modified in form and color, they make up the different parts of 

 the flower, as the sepals, petals, stamens, pistils, and sometimes 



