Scanning electron microscopy images of various crystals in primary roots collected from <i>Acacia</i> seedlings grown in the glasshouse.

<p>Arrow – crystal; filled arrow head – fibre cell; unfilled arrow head – cortical parenchyma cell; Xy – xylem: pentagon – developing lateral root. (A) Part of a cross section of an <i>A. ancistrocarpa</i> primary root showing crystals mainly in parenchyma cells associated with phloem fibre cells and in xylem fibre cells; (B) Prismatic crystals (filled arrow) in cortical parenchyma cells associated with phloem fibre cells and an amorphous crystal (unfilled arrow) in a cortical parenchyma cell of <i>A. ancistrocarpa</i>; (C) Prismatic crystals in cortical parenchyma cells associated with phloem fibre cells of <i>A. stellaticeps</i>; (D) Part of a cross section of a primary root of <i>A. robeorum</i> showing prismatic crystals mainly in parenchyma cells associated with phloem fibre cells and in xylem fibre cells; (E) Prismatic crystals in cortical parenchyma cells close to a developing lateral root of <i>A. robeorum</i>. Scale bars: (A, D, E) –100 µm; (B) –5 µm; (C) –20 µm.