160 LABORATORY AND FIELD EXERCISES 



b. Summarize the above points under body plan, growth 



methods of buds and branches, and tropistic responses 

 of leaves and branches. 



c. Long and dwarf shoots. 



Long shoots in pines are the main branches and 

 twigs; dwarf shoots are the small structures from 

 which the needle leaves arise in clusters of two, 

 three, or five. 



(1) Study long and dwarf shoots of pines in the field. 



Do the dwarf shoots arise in a spiral or cyclic 

 manner from the long shoots ? Study the naked 

 portions of a twig where the scars of dwarf 

 shoots show their former arrangement. Observe 

 the scalelike leaves on long shoots. What is 

 the arrangement of the scale leaves on the long 

 and dwarf shoots ? Do dwarf shoots arise from 

 the axils of scale leaves like ordinary branches ? 



(2) Buds and growth. Determine the nature and posi- 



tion of buds on long shoots. Are there lateral 

 buds ? Do dwarf shoots arise from lateral buds ? 

 Determine the age of a terminal portion of a long 

 shoot by the rings of bud-scale scars. 



(3) Draw a small portion of a long shoot from which 



dwarf shoots have fallen, to show their arrange- 

 ment on the long shoot and their relation to the 

 scale leaves. Draw the terminal portion of a long 

 shoot to show the shape and character of buds, 

 dwarf shoots, and needle leaves. It is best not 

 to draw more than one or two dwarf shoots on 

 the terminal shoot. 



d. Strobili, or cones (see Fig. 233, p. 379, of text). 



(1) Ovuliferous strobili. Observe the position of the 

 reproductive cones on single long shoots and on 



