SECTION I. PLANTS AND THE 

 ENVIRONMENT 



A. THE BODY PLAN AND FORM OF PLANTS 

 THE LILAC 



1. Leaves. Do the leaves spring from definite points on the 



axis of the main stem and its branches, or are they 

 irregularly arranged? Are they cyclic (two or more 

 leaves attached at the same level) or spiral in arrange- 

 ment ? Are the leaves so placed as to give the maximum 

 light to each leaf ? Observe the shoot from above. How 

 many rows of leaves are there along the stem ? Be able 

 to explain the light relations of the leaves. Consult 

 Figs. 5 and 6 of the text. 1 



2. Buds and branches. How are the buds related to the leaves 



as regards* position and arrangement on the stem and 

 branches ? Is there a terminal bud in the lilac ? Do 

 the branches have the same orderly arrangement as the 

 buds and leaves ? "Why ? Do branches grow from buds ? 



3. Stem divisions. Is the stem divided into regular divisions 



by the origin of leaves, buds, and branches from definite 

 points ? Consult the text under The Form and Plan of 

 the Plant Body concerning the nature and relation of 

 nodes and internodes. 



a. Sketch an entire shoot of a lilac in outline to show the 

 orderly plan upon which it is constructed. Eemove 

 the leaves on the side of the branch facing you and 



1 All text references are to Densmore's "General Botany." 

 3 



