Fig. 1

Diagrammatic representation of callose depositions in successive developmental stages of Z. mays (A–J) and V. sinensis (K–M) stomata. Newly formed (A), kidney-shaped (B) and dumbbell-shaped (C–J) stomata of Z. mays as well as newly formed (K), differentiating kidney-shaped (L) and mature kidney-shaped (M) stomata are shown. The cell wall regions rich in callose are marked in red. All the drawings represent stomata in paradermal view, except for (D–F) and (I), (J) that illustrate transverse stomatal sections. (D) shows a transverse view corresponding to the plane I of (C), while (E) a transverse view corresponding to the plane II of (C). The arrowheads mark the terminal thickenings of the central canal. (G) and (H) represent a closed and an open stoma respectively, in which callose is not depicted. CC central canal, DW dorsal wall, PVWE polar ventral cell wall end, SC subsidiary cell, VW ventral cell wall