Transverse sections of ectomycorrhizae associated with <i>E. grandis</i> X <i>E. urophilla</i> hybrids analyzed by SEM.

<p>(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 <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0067685#pone-0067685-g002" target="_blank">Figure 2c</a> (concretion) showing carbon, oxygen and calcium peaks. (e) Single crystal sand analysed by SEM (arrow). Scale bar = 5 µm. (f) Elemental spectrum of <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0067685#pone-0067685-g002" target="_blank">Figure 2e</a> (crystal sand) showing carbon, oxygen and calcium peaks.</p>