70 STUDIES OF THE LEAF 



lateral tendrils occupy the same relative positions on the main axis 

 (or rhachis) of the leaf as what other parts? What is the morphology 

 of the lateral tendrils? What three very distinct and different offices 

 does the leaf of the Pea fulfill ? 



Draw the entire leaf with its parts labeled. Show (by another 

 drawing if necessary) the mode of protecting the bud; indicate the 

 position of the bud by dotted lines. 



EXERCISE XXVI. TYPES OF VENATION 



Consider the character of the veining, and the arrangement or plan 

 of the framework, in the given leaves. 



Compare and assort the leaves. Divide them into groups according 

 to the similarities and differences in these respects. 



Draw the margins and main structure lines of the several leaves 

 (half the leaf will show the points wanted). 



After the notes covering the above, write a concise description of 

 each leaf, under the headings (1) Venation, (2) General Shape, 

 (o) Margin, (4) Apex, (5) Base ; referring to pages 77, 78, and 92-96 

 of this book for the proper terms. 



EXERCISE XXVII. COMPOUND LEAVES 



To which of the types of frame plan, studied in the last exercise, 

 does each of the compound leaves correspond, in the arrangement of 

 its leaflets ? Are the leaflets jointed to the main stalk ? 



Draw the given leaves in simple outline. Label each with the 

 proper descriptive term (see pages 96-99). 



EXERCISE XXVIII. SPECIAL USES OR MODIFICATIONS OF THE 



LEAF 



Barberry. Study the leaves subtending the lateral buds or leaf 

 clusters on a shoot of barberry. What is the use of these leaves ? 



Draw two or three examples to show transition from the foliage to 

 the spinelike condition. 



Onion. The material suggested is the Onion " set," or young bulb, 

 slightly sprouted. Note the outer, thin scales, for what purpose are 

 they formed ? What are they morphologically ? Cut the bulb in half, 

 lengthwise. Study the parts. Note the stem, producing roots, and 

 leaves. Some of the outer leaves are thickened, and do not extend 

 upward. What is their use? 



Draw the longitudinal section of the bulb, somewhat enlarged. 



Foliage of Acacia (Optional). What is the morphology of the flat, 

 green appendages of the stern? Answer after noting (a) their posi- 

 tion on the stem, (&) direction in which the surfaces look, whether to 



