THE SPERMAPHYTES. 



207 



THE PINES. PRACTICAL STUDIES. 



1. Examine any Pine tree as it grows. Is the stem 

 excurrent, i.e., does it rise as a central main shaft, or is 

 it deliquescent, i.e., does it divide 

 and subdivide into branches ? Are 

 the branches arranged in any par- 

 ticular way on the stem? If so, 

 state what the arrangement is. 

 Examine the apical bud at the end 

 of each branch ; also around its base 

 several lateral buds. The apical 

 bud develops into the shoot of the 

 next season ; the lateral buds de- 

 velop into the new branches. Start- 

 ing with the top of a young Pine, 

 can you tell how much is this sea- 

 son's growth? Can you trace the 

 growth of the different years down 

 the stem ? Cut across the stem 

 where it is at least half an inch in 

 diameter. Count the . number of 

 rings of annual growth. How does this number com- 

 pare with the age as determined by tracing the growth 

 of the different years down the stem ? Notice the color 

 of the bark. Is the bark on the stem and also on the 

 branches smooth or rough? Observe the scale leaves on 

 the branches. Notice that the foliage leaves are produced 

 on short dwarf branches. Describe the surface of the 

 dwarf branches. How many leaves grow on a branch ? 

 Notice the sheath at the base of the leaves. Examine 

 different Pine trees. Is the number of leaves on a dwarf 

 branch the same in the different species? Identify the 

 species studied by consulting Gray's "Manual." 



FIG. 133. Longitudinal sec- 

 tion of the nucellus of 

 the naked ovule of the 

 Gymnosperm, Juniperus 

 Virginiana. p is a pol- 

 len grain which is send- 

 ing its tube down into 

 the ovule. (After Stras- 

 burger.) 



