PLANT STEMS 293 



that in the corn-stalk the woody fibres are scattered 

 irregularly through the pith, while in the tree stem 

 the wood is arranged in circles around the pith. Make 

 drawings of the cross sections to show this. 



Cut the stems into longitudinal sections, and make 

 drawings to show the arrangement of the wood and 

 pith. 



These two kinds of stems represent the two great 

 groups of flowering plants having closed seed vessels 

 monocotyledons and dicotyledons. The corn stem be- 

 longs to the former, and the tree stem to the latter. The 

 grasses, lilies, palms, etc., are monocotyledons, and the 

 trees, most of the weeds and grains are dicotyledons. 



2. Field Study of the Corn Plant 



Go to the nearest corn field, and note your observa- 

 tions on the following points : 



1. How many joints and how many blades have 

 formed on the corn stems? 



2. Would you prefer stalks with short or long inter- 

 nodes ? Why ? 



3. Why do stalks grow tall and slender when planted 

 too thickly? 



4. If the ear has formed, count the number of nodes 

 above and below it. 



5. What height above the ground would you think 

 best for the ear to be ? 



6. Note how the blade is attached to the stem. 



7. Note the stem above the last node. It develops 

 into the tassel. 



