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The development of the water transporting xylem tissue in plants involves an intricate interplay of Rho of Plant proteins (ROPs) and cortical microtubules to generate highly functional secondary cell wall patterns, such as the ringed or spiral patterns in early-developing protoxylem. Simulation models have been crucial in understanding the self-organisation of the highly dynamic cortical microtubule array, suggesting important roles for microtubule-dependent nucleation and co-alignment of the microtubule array and ROP pattern in speeding up the band formation process. So far, however, no one has been able to reproduce a banded pattern for realistic microtubule behaviour, as past implementations of microtubule-based nucleation created an inhomogeneity problem that has only recently been solved. Here, we study the requirements of protoxylem band formation with computer simulations in corticalSim, extended to include finite microtubule persistence length and a novel algorithm for microtubule-based nucleation that allows for local feedback on microtubule density but avoids global competition for nucleation events. We find that microtubule-flexibility is required to increase the mismatch tolerance of the ROP and microtubule pattern to realistic levels. At the same time, flexibility leads to more catastrophes, both induced catastrophes and catastrophes from the microtubule-hostile gap regions. This effect results in a loss of microtubule density, making it harder to maintain microtubule bands. Microtubule-dependent nucleation helps to counteract this effect by moving some nucleations from the gap regions to the bands once microtubules …