tary pores appear more common than multiples. The rays are fine and
inconspicuous. The wood is best identified on the basis of microscopic
features: the rays are narrow, 1–3 (mostly 1 or 2) seriate. Vessels have very
small (3–4 μm diameter) intervessel pits and simple (only occasionally
scalariform) perforation plates. Spiral thickenings are commonly absent,
although sparse spiral thickenings are occasionally present.
There are several other woods of the Rosaceae family that have
anatomical features very similar to those of pear. These include apple
(Malusspp.), hawthorn (Crataegusspp.), and mountain-ash (Sorbusspp.).
Woods ofthis group usually cannot be separated with certainty and are
summarily identified simply as fruitwood.
Lime(Tilia spp.) has neither characteristic visual features nor dis-
tinctive heartwood color. Hand-lens examination of transverse surfaces
shows evidence of growth rings by slightly denser latewood fiber mass,
the growth-ring boundary often delineated by a lighter line of latewood
parenchyma (Fig. 22). Rays are fairly distinct and appear to flare (widen)
as they cross the growth-ring boundary. Sections examined microscopi-
cally show vessels with simple perforations and fairly large intervessel
pits. A key feature is the very thick spiral thickenings, which are conspicu-
ous in the vessels (Fig. 26a). Tangential sections show that the rays are
mostly 1–4 seriate, the ray cells appearing flattened or oval rather than
rounded (Fig. 27c).
Poplaralso lacks distinctive color and visual features. On cross sec-
tions viewed with a hand lens, the appearance of the pores may suggest a
semi-ring-porous arrangement. Pores appear numerous, and multiples are
common; the rays appear extremely narrow and are barely visible (Fig. 23).
Under a microscope, tangential sections show that the rays are exclusively
uniseriate (Fig. 27a). Intervessel pits are large and distinct and rounded or
angular through crowding (Fig. 25a); intervessel pitting is easily found on
tangential sections because of the numerous radial multiples. Vessels lack
spiral thickenings, and the perforation plates are simple (Fig. 24b). Radial
sections show distinctive large ray-vessel pitting in marginal rows of ray
cells (Fig. 28a).
Willowappears confusingly similar to poplar and has many of the
same anatomical features: diffuse-porous to semi-diffuse-porous structure
with moderately fine texture, exclusively uniseriate rays, and vessels lacking
spiral thickenings but with large intervessel pitting and simple perforations.
The only consistent distinguishing feature is that poplar has exclusively
homocellular rays, consisting entirely of radially elongated procumbent
cells, whereas willow has heterocellular rays, which include both procum-
bent ray cells and upright ray cells (Fig. 28b). Viewed radially, upright ray
cells appear more or less square or may be elongated in the longitudinal
direction; they occur mostly in one or more rows along the upper and
lower margins of the rays (compare Fig. 28a and Fig. 28b). The upright
ray cells in willow also have distinctively large ray-vessel pits.Among the woods commonly used in panel paintings, only a few, such as
oak and beech, have visual features that suggest an immediate identification.
For some, such as ash, elm, and chestnut, hand-lens examination of end-
gr ain surfaces may suffice. For most, however, identification is best accom-
plished through microscopic examination of thin sections oftissue. Because
the relatively short list of woods reviewed in this article covers most woodsSummary
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