LABORATORY EXERCISES 13 



Storage stems (cactus). What is stored? Note the condition of 

 the leaves. Where is the chlorophyll? 



Cladophylls (Myrsiphyllum). What are the small scalelike struc- 

 tures borne by the stems ? What are the leaf-like organs (cladophylls) 

 borne in the axils of the scales? 

 Thorns: 



(a) What are the thorns on the black locust? 



(b) What are the thorns on the holly and barberry? 



(c) What are the thorns on the honey locust? 



Tendrils: Compare the tendrils of the grape and Virginia creeper. 

 Why are they branches? Note how the grape tendril is coiled. 



Modified Leaves 



Scale leaves. Recall various types already studied. 



Tendrils. Compare leaves of the pea, vetch and vetchling. What 



are the tendrils in each? 



Thorns. See paragraph 66, a and b. 



Storage leaves: 



(a) Compare leaves of Portulaca and the houseleek. 



(b) Make a longitudinal section of an onion. What are the scales? 

 (Where is the stem?) 



Traps: 



(a) The sundew (Drosera). Note how the hairs on the leaves react 

 to contact with a gnat or other small insect. 



(b) The pitcher plant (Sarracenia) . What devices are employed for 

 catching insects? 



(c) The Venus flytrap (Dionaea). 



X. Flowers 



A simple type of regular flower (Oxalis). 



(a) Make a diagram of the flower as it would appear in longitudinal 

 section. 



(b) Make a "plan" diagram to show how the parts are arranged 

 around the center. 



(c) Draw one member of each cycle. For terms see text. 



(d) Make a cross section of the ovary. 



A simple type of irregular flower (Swainsona). Study as in 73. 

 Study other more modified types of flowers such as Primula, etc. 



