BUDS AND STEMS 



107 



another through the open ends of the cells. We find the conducting tubes 

 have quite different functions : Some carry soil water and air up the stem, 

 while others take food material down 

 toward the roots. As the bundles grow they 

 elongate rapidly, but are limited in their 

 growth outward by the hard- walled, woody 

 cells. An old stem of a monocotyledon con- 

 tains more bundles than does a young stem, 

 the bundles growing out into the leaves. 



Monocotyledonous fib ro vascular 

 bundle; p/i, region in which food 

 passes down; d, woody portion 

 or bundle ducts which carry air 

 and water; p, pith cell. 



Summary. — A stem of 

 corn contains pith, dead 

 tissue which is the original 

 soft; spongy material out 

 of which the stem is 

 built, and a great mass of 

 woody cells, many of them 

 tough and fiberlike, serv- 

 ing to support the stem; 

 others are long cells, hol- 

 low and end to end, form- 

 ing tubes which connect 

 the roots with the leaves, and through which fluids pass in both 



directions. 



The stem of corn also contains a supply of stored food. Some 

 of the cells of the pith store food, which is often being made faster 

 than it can be used by the plant. Many monocotyledonous trees 

 which live for long periods of time store food in large quantities 

 in the trunk. The sago palm is an example. 



Palms and palmettos; typical monocotyledonous 

 plants. Scene on Indian River, Florida. 



