Fig. 2

Images indicating compression wood severity index, classified according to the grading system of Yumoto et al. (1983) and revised from Timell (1986a, b). A = very faint round cells; B = slightly round cells and slightly thicker cell walls; C = fairly round cells with thicker cell walls; D = round cells with some intercellular spaces and relatively thick cell walls; I = round but not fully circular cell with intercellular space and thick cell walls; S = nearly circular cells with intercellular space and very thick cell walls