Perforation plate:
Opening between two adjacent vessel elements.
Section
r radial t tangential q transversal
Diagnostic
Value
h high me medium mo modest
Simple perforation plate:
Round to oval opening in the end wall of a vessel element.
r
h
Scalariform perforation plate:
The round to oval opening of the end wall of a vessel element is subdivided
by bars. Often all the transition forms from the simple to the scalariform
perforation plates are present.
r
h
Spiral thickenings:
Helical ridges on the internal face of the secondary wall.
r/t
h
Spiral thickenings in fiber-tracheids.
r/t
h
Spiral and annular cell wall thickenings in vessels
of the proto- and metaxylem. These thickenings, which are found in
all the species, are not useful as identification characteristics.
Attention is thus necessary in the identification of twigs.
r/t
mo
Fiber-tracheids:
Fiber-like tracheids in the xylem with thick walls and small bordered
pits (no perforation plates).
r
h
Libriform fibres:
Fibers in the xylem with thick walls and small slit-like pits.
r
me
Septate fibers: Similar to Libriform fibres,
however with thin transversal walls.
