Chapter Eight 

 STEMS AND BUDS 



The stem is the structure, usually above the ground, 

 which bears the leaves. It develops from the plumule part 

 of the seed (Plate 1) . The tomato seedling at the left shows 

 only a bud-like plumule which develops into the shoot in the 

 other two stages. There are a few underground stems such 

 as the white potato tuber and the rhizomes of quackgrass 

 and ferns. 



The nodes of stems are usually swollen areas from which 

 the leaves grow. The above plate shows a node with its com- 

 pound leaf, and the buds which appear just above the leaves 

 develop into branches (Plate II). The two growing buds 

 may be seen just above the lower compound leaves; the 

 upper one is a sizeable branch. The length of internode, 

 which is the distance between two nodes, depends largely on 

 the growth conditions at the time of development. If they 

 are too long the plant probably lacks light, has too much 

 water, or nitrogen. The cabbage plants shown in Plate III 

 were grown with light and minerals limited to starve them. 

 They show many leaf scars very close together because the 

 internodes are short. 



Stems of garden plants are of two kinds, first monocoty- 

 ledonous, such as corn and lily, which usually grow in length 

 chiefly at the base of the internodes, branch sparingly, in- 

 crease in diameter only a little, and have the woody fibers 

 scattered more or less evenly through the pith. The second 

 are dicotyledonous plants, such as tomato and all broad- 

 leaved trees, which differ in all these particulars. They grow 

 in length just back of the terminal bud, branch more freely, 

 increase in diameter by adding cells at the cambium layer, 



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