The structure of reaction wood as indicated by scanning electron microscopy

Abstract

Scanning electron microscopy was used to investigate the structure of normal and reaction wood of Cupressus arizonica Greene, Pinus canariensis C. Sm., and P. radiata D. Don. The wood of P. radiata was examined before and after various chemical treatments. These included chlorine water-sodium hydroxide, glacial acetic acid-hydrogen peroxide, sodium hydroxide-sodium sulphide, 17.5 % sodium hydroxide, 78 % phosphoric acid, 72 % sulphuric acid, 1 % osmic acid, and 2% potassium permanganate.

The helical ribs of the S2 layer in reaction wood cells appeared to be multistranded. Warts tended to become fewer and restricted to the grooves in the S2 layer during the change-over from normal to reaction wood cells. The origin and chemical composition of the warts and associated membrane are considered.