32 Elementary Work in Botany. 



EXERCISE 20. 



Study of a Woody Stem. Note the arrangement of 

 the leaves; or, if they have fallen, the leaf scars. Hold the 

 stern so that one of the lower leaves or its scar is on the 

 side next to you. Beginning with the next leaf, count 

 upward to the fifth. On what side do you find it ? Count 

 five more. On what side do you stop ? Move your pencil 

 point upward from leaf to leaf the nearest way. Is the 

 spiral thus traced like that of a common screw in direction ? * 



How many turns of the spiral leaf-line from the 

 first leaf to the sixth ? Leaves grow from nodes, and 

 the spaces between leaves or nodes are called inter- 

 nodes. Draw a line directly down the stem from the 

 second leaf to a point opposite the first. In the same way 

 find the point on the first node exactly below the third leaf 

 and so on to the fifth. You- have now on one node four 

 points and a leaf or a leaf scar. Suppose the four inter- 

 nodes which separate the five leaves had failed to grow. 

 Do you see that the five leaves would have formed a whorl ? 

 How many such whorls would the leaves on the stern make ? 

 Do you find buds in the axils of all the leaves ? (Above the 

 leaf scars on a leafless stem.) Which buds are largest ? 

 What can you say of the size of the terminal bud ? Which 

 of the axillary buds were designed to make branches next 

 year? Of what use are the other buds? What is the use 

 of a terminal bud ? Draw the terminal bud and the last leaf 



* If the class have more than one kind of sprout, they should exchange speci- 

 mens and compare. 



