BIOLOGY OF HIGHER SEED PLANTS 



which the parts are attached ? This point can be 

 demonstrated by bisecting the bud. See Fig. 2, and 

 Fig. 37 (p. 68) of the text. 



b. Sketch the external surface of a bud and label its parts. 



c. G-rowth of buds. Do all of the buds in the axils of the 



leaves grow each season ? Ex- 

 amine older portions of the 

 branch to determine this point. 

 Are the branches produced each 

 season of the same length and 

 vigor ? Note the forked branch- 

 ing due to the growth of the 

 two vigorous subterminal lat- 

 eral buds. Can you determine 

 the age of the branch you are 

 studying ? Look for the scars left 

 by the bud scales each season 

 (Fig. 1, and Fig. 38 of the text). 



5. The shrubby form of the lilac. Study 



the form of the branch with which 

 you are working, as well as that 

 of lilac shrubs in the field. Is the 

 rounded, shrubby habit of the lilac 

 due to the arrangement and method 

 of bud growth ? For example, sup- 

 pose the lilac shoots had a single 

 continuous terminal bud instead of the two subterminal 

 ones. Would this change the form and habit of the plant ? 



6. Summary of observations. Answer the following ques- 



tions in the form of a summary on your laboratory sheets : 



a. What relation exists between the position and arrange- 



ment of leaves, buds, and branches in the lilac ? 



b. What is meant by the body plan of the plant body ? 



FIG. 2. Vertical section 

 of a hawthorn bud 



br and o, outer and inner 

 bud scales; i, i lt outer 

 and inner leaves ; g, 

 growing point, or meri- 

 stem, of the bud. From 

 Bergen and Caldwell's 

 "Practical Botany" 



