Figure 1. 1D, 2D and 3D apical cells.

(A) Schematic diagram of an apical cell with one cutting face (1). (B) Schematic diagram of an apical cell with two cutting faces (1, 2). (C) Schematic diagram of a shoot tetrahedral apical cell of P. patens with three cutting faces; daughter cells are cut off from three rear faces (1, 2, 3) but never the shootward face that caps the shoot apex.