Pore aperture/guard cell pressure relationships for a barley stomatal FEM model in which the SCs have been digitally ablated, leaving the isolated GCs. With cellulose anisotropy maintained as in the original FEM model, pore aperture increases as GC pressure increases (yellow line) but the initial pore aperture at low GC pressure is larger than that in the intact reciprocal pressure FEM model (response curve in black, as shown in A). When anisotropy is removed from the isolated GCs and stiffness set at a relatively low level in the FEM model, the aperture/pressure response curve is similar to that observed with anisotropy present (green line). As GC wall stiffness is increased in the isolated GCs, the aperture/pressure response curve shifts downward, with pore aperture remaining large at low GC pressure (dotted green line).
