STEMS 125 



What is the effect of this kind of growth on the form of 

 tree trunks ? 



Compare the shoots with sumach, bramble, blackberry, 

 and raspberry shoots. 



Conclusion. As in Experiment 110. 



Note. When a plant makes all its annual growth in the spring, 

 it spends the remainder of the season in making preparation for 

 cold weather. This is accomplished by the production of woody 

 tissue in its stem to the very tip and by the development of bud 

 scales for the protection of future branches and flowers. Such a 

 plant is said to have definite annual growth. 



Many plants, however, keep on growing all summer, and cold 

 weather finds the ends of their stems soft and tender. The first 

 frost kills the tender tips because no wood has had tune to mature 

 within them. Thus if warm weather continues into the autumn, 

 such plants will have long shoots. But should an early frost come, 

 these branches will be much shorter. Such a plant is said to have 

 indefinite annual growth. 



112. TWIGS 



Object. Same as in Experiments 110 and 111. 



Apparatus. Twigs of catalpa. 



Method. As in the preceding Experiments. The catalpa 

 represents a different arrangement of leaves and branches. 

 What is it ? Are the leaf scars alike in size ? If not, which 

 ones are smaller? What does this show regarding the posi- 

 tion of the branch on the parent tree ? 



Conclusion. Similar to preceding. 



Suggestion. Collect twigs of as many common trees 

 as possible. Mount them on cards for comparison. 



Which have opposite branching? 



Which have alternate branching? 



Which have whorled branching? 



