Fig. 3. Self-supporting and lianescent xylem anatomy.
(a ) Stem cross-section showing self-supporting xylem
(SS) , characterized by small radially arranged vessels formed
only by the fascicular cambium, opposite to protoxylem poles (black
arrows), and a high proportion of fibers. The beginning of the
lianescent xylem (L) is marked by the concomitant production of several
large vessels (white arrows) not restricted to radial files and the
reduction of fiber amount. The large vessels are associated with small
vessels and comprise a larger proportion of the xylem in this phase.
(b ) Longitudinal radial section of the xylem. Ray composition
changes from upright cells in SS to mainly square and
procumbent cells in L (white arrows). Septate fibers
(arrowheads) are found in both phases. Vessel (v). (c )
Self-supporting and lianescent xylem vessel diameter classes
distribution. Scale bars: (a) 125 μm; (b) 100 μm.
This
analysis highlights the distinct characteristics of self-supporting and
lianescent xylem, including the broader distribution of vessels in the
later phase, no longer restricted to the fascicular regions. The
production of large vessels in the lianescent phase significantly
increased water potential specific conductivity and reduced the number
of cells per area.
Table 1. Quantitative characterization of self-supporting and
lianescent xylem.