THE SPKING FLORA 159 



GYMNOSPERMS (SOFTWOOD TREES) 



THE PINE 



1. Habitat. 



a. What is the nature of the habitat of the pines of your 



region as regards soil, drainage, and climate ? Do 

 pines grow best on lowlands or on well-drained 

 slopes and uplands? What is the distribution of 

 pines in the United States ? What is their natural 

 habitat as regards soil and climate ? Are they 

 mesophytic or xerophytic in general habit ? How 

 do you explain the apparent discrepancy between 

 habitat and habit in the pines ? Consult the text, 

 manuals, and assigned readings on the above points. 



b. Summarize the above points in your notes under the 



following headings: 



(1) Habitat : local geographical 



(2) Habit : mesophytic xerophytic 



(3) Discrepancy between habitat and habit 



2. Habit. 



a. Form and body plan of the pine tree. 



Eeview the text discussion of the body plan and 

 mode of growth of the pine tree in Part I of the text. 

 Consult also Fig. 10. Be able to account for the 

 erect conical form, the excurrent trunk, and the 

 false whorls of branches of common pines. Why 

 is the trunk excurrent ? What determines the cone- 

 like form of the entire tree? How do the false 

 whorls arise ? Is the entire leafage well exposed to 

 light ? What factors determine this light exposure ? 

 Is it due to the form of the tree, to tropisms of 

 leaves and branches, or to other factors ? 



