and Laboratory Methods. 2623 



1. Study and sketch a branch of the Austrian pine, showing scale leaves, 

 dwarf branches, and foliage leaves (needles). How old is the branch studied ? 

 What two ways of telling the age ? Are the foliage leaves deciduous ? How old 

 are the dwarf branches before they are self-pruned? Where do the ordinary 

 branches originate, and when ? 



2. Draw a dwarf branch, with scale leaves and foliage leaves, of the Aus- 

 trian pine, Scotch pine, pitch pine, and white pine. Note the peculiarities of 

 each dwarf branch. 



3. Under low power, without cover-glass, draw part of the foliage leaf of 

 the Austrian pine, showing the stomata. How are they arranged? Draw a 

 scale leaf from the ordinary branch and one from the dwarf branch. Note the 

 difference between the foliage leaves and the scale leaves. 



4. Cut cross sections of a foliage leaf, mount and study under low power. 

 Draw and note the following tissues : epidermis with sections of the stomata, 

 heavy-walled hypodermal tissue, green mesophyll with a number of resin-ducts, 

 and the light-colored central region with two vascular bundles. 



(b) Other Conifers. 



Collect branches of the following: Pinaceae — the European larch {Larix 

 decidiia Mill.), Norway spruce {Ficea excelsa (Lam.) Link.), Canadian hemlock 

 {TsHga canadensis (L.) Carr.) ; Juniperaceae — arbor vitae {IViiija occiden talis L.). 



L Sketch the larch branch, showing the large dwarf branches. Compare 

 with Ginkgo and Pinus. Note that the foliage leaves are deciduous annually, 

 and that the dwarf branches may develop into ordinary branches. Are the 

 dwarf branches deciduous (self-pruned)? 



2. Sketch a short branch of the Norway spruce and note a slight tendency 

 to bilateral symmetry, and how the leaves are bent from the under side to obtain 

 a proper I'ght relation. 



3. Sketch a branch of the Canadian hemlock with carpellate cone at the 

 end. Note bilateral arrangement and the light relation of the leaves, especially 

 the small ones on the upper side. 



4. Sketch a small branch of the arbor vitae. Note the flattened condition 

 of the stem and the leaves. Note also that numerous branches of various sizes 

 are self-pruned. 



(c) Structure of White Fine Stem. 



Preserve pieces of branches, five or six years old, in alcohol, and also obtain 

 large, polished cross sections (about two inches thick) of a tree-trunk with bark. 



L With a strong, sharp razor, cut cross, tangential, and radial sections of 

 stems in alcohol, mount, and stain with iodin ; or study prepared slides. 



2. Draw part of a cross section under low power, showing epidermis, cortex, 

 with resin passages, phloem, cambium, xylem in a number of annual rings with 

 medullary rays and resin passages, and central pith. 



3. Radial section. Draw under low power, showing cortex, cambium, xylem 

 (composed of tracheids), and pith. Note the medullary rays passing from the 

 pith to the phloem. 



