LABORATORY AND FIELD EXERCISES 



c. What relation have the position and growth of buds to 

 the form of the lilac shrub ? Illustrate this point by 

 means of an outline sketch. 



HERBACEOUS PLAXTS 



Use the catnip, ragweed, aster, or similar herbaceous plants 

 for this study. 



1. The main axis. What is the form of the entire central 



axis of the plant, including both stem and root ? Is this 

 central axis me- 

 chanically adapted 

 to the support of 

 the lateral roots, 

 branches, and leaves ? 

 Be able to explain 

 to an instructor. Is 

 the main axis of the 

 stem the same in 

 shape as that of the 

 root ? Is the entire 

 axis divided into 

 nodes and biter- 

 nodes ? Are the in- 

 tern odes of the 

 same length in all 

 parts of the axis ? 



2. Lateral members. Are 



the leaves cyclic or 

 spiral in arrange- 

 ment ? How many 

 of the lateral buds 

 have produced branches ? Have these lateral branches 

 the same plan and leaf arrangement as the main 



FIG. 3. Cyclic body plan and leaf dis- 

 play of the milkweed (Asclepias) 



Note that the cyclic leaf arrangement 

 secures the maximum light exposure. Pho- 

 tograph by Jesse L. Smith. From Bergen 

 and Caldwell's "Introduction to Botany " 



