Fig. 2

Light micrographs of radial sections stained with acetocarmine (a, b) and iodine–potassium iodide (c, d), showing nuclei (black arrowheads) and starch grains (white arrowheads), just before the formation of new periderm (Stage 0) in Tree A in June, 2016. b, d Higher magnification images of the selected areas in a, c. White arrows indicate the innermost periderms. AP axial parenchyma cell, F phloem fiber, IB inner bark, Pr periderm, Rh rhytidome, RP ray parenchyma cell. The right side of each micrograph corresponds to the outer side of the tree. Scale bars = 200 µm in a, c; 100 µm in b, d