Fig. 2. Light micrographs showing phellogen cells of wound periderm. Arrowheads indicate radial walls. A, Immature wound periderm. B, Mature wound periderm. Bar = 2 µm. Note that the phellogen radial wall of the mature periderm is thicker than that of the immature periderm. Mean phellogen radial wall width for immature periderm = 146 + 27 nm (n = 21) and for mature periderm = 357 + 31 nm (n = 23). Means are significantly different at P = 0·01.