4 
LABORATORY EXERCISES 
III. Why is a flower an important structure? Which of the 
parts observed are the essential parts of the flower? Draw a 
flower, showing the parts. 
EXERCISE 4 (Supplementary) 
TYPES OF SIMPLE FLOWERS 
Use simple flowers, such as the snapdragon, petunia, morning- 
glory, sweet pea, and phlox. At least six different flowers should 
be used in this exercise. 
I. Note whether the flowers are borne singly or in clusters. If 
borne in a cluster, what are the characteristics of the cluster? 
II. Compare the floral parts of each flower with those of the 
simple flower which was first studied. Note any peculiar adapta¬ 
tion of parts or any specialization of structures which may be 
present. Determine if possible what relation, if any, each special¬ 
ized structure bears to pollination. 
EXERCISE 5 (Supplementary) 
A COMPOSITE FLOWER 
Use a sunflower, a cosmos, or some similar type of composite 
flower. 
I. Compare this “ flower with the simple flowers previously 
studied, in regard to its size, its position on the plant, etc. Note 
the parts which appear to resemble the floral parts of a simple 
flower. Remove some of the petal-like structures and some of the 
parts nearer the center. Examine the base of each. Note, on an 
older specimen, into what these parts may develop. What is each 
of these parts? What then is the entire flower ” of this plant? 
II. The inner parts are disk florets. The outer are ray florets. 
Study each, determining what floral parts are present. The sepal¬ 
like structures outside the florets are the bracts. The circle of the 
bracts is the involucre. What is the function of the involucre? 
