180 MORPHOLOGY AND LIFE HISTORY 



length each year? Find evidence that they 

 do not. 



(b) Compare the number of needles borne by each 

 dwarf branch. Is the number constant? On 

 what/part of the branch are they borne? 



(c) Note the bud-scales, some of which form a 

 sheath about the bases of the needles. 



4. The Foliage-leaves. 



(a) Describe their shape. Are they differentiated 

 into petiole and blade? 



(b) Make a drawing, natural size, of an entire leaf, 

 and a diagram (X 10) of a cross-sectional view. 



5. The Terminal Bud. 



(a) Describe its color, coverings (bud-scales), 

 and shape. Draw (X 3). 



(b) With the scalpel remove one of the bud-scales 

 at its base. Describe and draw (X 5). 



(c) Now remove, one at a time, the remaining bud- 

 scales, having care not to break or injure the 

 tender inner tissues. 



(d) Describe the place and mode of attachment 

 of the scales. 



(e) Explain how they are adapted, in structure and 

 position, to protect the bud. From what do 

 they protect it? 



(/) Describe the color of the inner tissues. Can 

 Pinus form chlorophyll in the dark? Explain. 



(g) Make a drawing (X 5) of the bud after the 

 scales have been removed. 



(h) With a sharp scalpel make a median longi- 

 tudinal section of the bud. Observe the central, 

 conical axis, bearing thin membranous scales. 

 In the axil of each scale find a small knob-like 

 outgrowth. 



