The Broken Fork
All my ESEM images not only come from fractured wood;
more specifically, they come from in and around the
fracturing of branch junctions. There is an intense zone
of wood with very different qualities than surrounding
wood that forms in the axil of a branch junction and that
is marked externally by that junction's bark ridge. This
wood is much denser, with a higher proportion of wood
fibers and fewer vessels—and it makes tortuous and
interlocking patterns with its wood grain. The specialized
wood that forms in these axils is called axillary wood.
These two images show the 'spine' of tissues one
often finds when breaking apart a young branch junc-
tion; on the left is a larch and on the right, a beech.
For a snapped branch junction, the fracture surface
along the axillary wood is often a mix of fibers snapped
along their length or fibers extracted from the base of
one of the two branches that were previously joined.
Both effects can be seen in these two images: where
fibers are extracted, you get a spur of tissues projecting
from the fracture surface; where fibers were snapped,
you can see their lumen and spirals of cellulose strands
emerging from the fracture surface. Again, to achieve
this, one is snapping some fibers along their length,
which explains how much of the strength of branch junc-
tions is conferred by this centrally-placed axillary wood.
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