references of wood anatomy to see how variable or how consistent
different specimens of a species can be.
The equipment necessary for a wood identification procedure
includes a sharp knife or other woodworking tool for exposing fresh wood
surfaces or for removing small specimens, razor blades (single- and double-
edged types) for final surfacing and sectioning, a 10 3 hand lens, a trans-
mission light microscope (capable of magnification up to 400–500 3 ), glass
slides, cover glasses, and an eyedropper. It is preferable that the investiga-
tor have reference samples of the species under consideration so that he or
she can compare key features to those seen in the reference samples rather
than relying on the written material and photographs alone.
As an initial step, a transverse surface of the unknown wood
should be examined with a hand lens to determine whether the wood is a
hardwood or a softwood. If there is any difficulty in establishing this dis-
tinction, a transverse section quickly examined under the microscope will
show the radial rows of tracheids that characterize softwoods or the var-
ied cell types with larger pores characteristic of all hardwoods.
Softwoods
With the hand lens alone, identification of the conifers is tentative at
best, but it is usually worthwhile to evaluate any noteworthy macroscopic
features. Coniferous wood tissue consists mainly of small and indistinct
tracheids, and in transverse view the overall cellular appearance is confus-
ingly similar among all conifers, as shown among the examples presented
in Figures 4–7. Within a growth ring the contrast between earlywood and
latewood may be characteristic. For example, in Scots pine (Pinus sylvestris)
and larch (Larix spp.) there is a rather abrupt transition from the lighter
mass of earlywood tracheids to the darker, denser latewood; in spruce
(Picea spp.) and fir (Abies spp.) there is less contrast between earlywood and
latewood, and the transition from earlywood to latewood is more gradual
than abrupt.
One important feature seen under the hand lens is resin canals,
which are tubular passageways formed by a cylindrical sheath of cells called
epithelial cells. During the sapwood stage, the epithelial cells are living and
exude resin into the resin canals. The resin canals, being three to five times
the diameter ofthe surrounding tracheids, are visible on transverse sur-
faces under a hand lens. Among the conifers covered in this article, resin
canals are present in pine (Pinus spp.), spruce, and larch (Figs. 4–6). Fir,
however, does not contain resin canals (Fig. 7).
In pines the resin canals are large, solitary, and usually conspicu-
ous, relatively numerous, and uniformly distributed in virtually every
growth ring. In spruce and larch the resin canals are smaller and less
numerous, and they tend to occur unevenly. They are apparently absent in
some growth rings but may occur in tangential groups of two or more.
For coniferous woods, observations such as those discussed above
will suggest possible answers, but minute features evident through micro-
scopic examination of tangential and radial thin sections provide the most
reliable basis for identification.
Routinely useful microscopic features include the height and
width of the rays (as determined by cell count) viewed tangentially; in
radial view, diagnostic features include the types of ray cells present, the
shape and number ofcell-wall pits (voids in the cell walls connecting to
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