Series editors' preface - Wood Tools

Figure 2.9 Tangential microscopic view showing spiral
thickening in tracheids in yew. This distinctive feature,
along with the absence of both resin canals and
longitudinal parenchyma, distinguishes yew from other
conifers
Among the hardwoods – the diffuse-porous
hardwoods especially – microscopic analysis
also provides the best means of confirming
many genera, and in most cases, the only way
of separating species within a genus. For
example, in Betula (birch), the multiple grate-
(a) (b)
Wood and wooden structures 71
Figure 2.10 The scalariform perforation plate (the
ladder-like feature also seen in Figure 2.4b) in
combination with the numerous tiny pits (minute
alternate inter-vessel pitting) are distinguishing features
of birch (Betula spp.)
like end walls (scalariform perforation plate)
separating consecutive vessel elements together
with the numerous tiny pits (minute
alternate inter-vessel pitting) laterally connecting
vessels, are distinguishable features of this
genus (Figure 2.10).
Figure 2.11 Radial microscopic views of black walnut: (a) shows crystals in longitudinal parenchyma cells; (b)
shows reticulate thickenings, called ‘gash-like pits’, in late-wood vessel elements. These two features can be used to
separate North American black walnut (Juglans nigra) from European walnut (Juglans regia) as they are present
only in the North American species