Anatomical Analysis of Bark Structure of Toxicodendron vernicifluum with Different Amounts of Lacquer Production

Abstract

Anatomical features of the inner bark of three clones of urushi trees (Toxicodendron vernicifluum) with different amounts of lacquer production were investigated with light microscopy and cryo-scanning electron microscopy. All of trees showed a similar structure of inner bark. They formed longitudinal resin canals and traumatic resin canals close the cambium in the inner bark. Cryo-scanning electron microscopic images showed that all of longitudinal resin canals and traumatic resin canals were filled with resin. Trees of clone with higher amounts of lacquer production formed wider inner bark, higher number of resin canals and larger cross-sectional area of resin canals than those with lower amounts of lacquer production. In addition, trees of clone with higher amounts of lacquer production formed more traumatic resin canals close to the cambium than those with lower amounts of lacquer production. Our observations suggest that the structure of inner bark, in particular the quantity and size of resin canals, might be suitable anatomical index for the clonal selection of trees that produce higher amounts of lacquer.