Fig. 4

Schematic layout of a XyDyS simulation. The gradient of signal concentration (blue dots) imposes both cell identities and growth rates. Cells with a concentration above the division threshold (T _d ) have the ability to divide. Cells with a concentration above the enlargement threshold (T _e ) are growing, with a growth rate proportional to the concentration. The zonation is based on cell identity and geometry. Cambial zone (CZ, green): small (L _i <2L _{i n i t} ) growing cells. Enlargement zone (EZ, blue): large (L _i >2L _{i n i t} ) growing cells. Thickening zone and mature zone (TZ + MZ, red): non-growing cells