Transverse sections of ectomycorrhizae associated with E. grandis X E. urophilla hybrids analyzed by SEM.

(a) Two calcium oxalate concretions (arrows) located within cortical root cells. Scale bar = 50 µm. (b) Single crystal sand calcium oxalate (arrow) located within cortical root cell. Scale bar = 2 µm. (c) Single concretion analysed by SEM (arrow) showing its irregular surface. Scale bar = 10 µm. (d) Elemental spectrum of Figure 2c (concretion) showing carbon, oxygen and calcium peaks. (e) Single crystal sand analysed by SEM (arrow). Scale bar = 5 µm. (f) Elemental spectrum of Figure 2e (crystal sand) showing carbon, oxygen and calcium peaks.