Arabidopsis thaliana sepals grow to the same shape and size consistently, allowing them to function properly to protect the immature flower. Cell growth rate and direction is heterogeneous during sepal development, but heterogeneity accumulates over time to be more uniform across the tissue. The ftsh4-5 mutant has a loss of robust development of sepal size and shape which is caused by decreased heterogeneity in cell growth rate and direction, leading to uneven accumulation of growth. Elevated levels of reactive oxygen species (ROS) cause this phenotype, but the mechanism by which ROS affects growth heterogeneity is unclear. It is possible that a feedback loop is involved in growth heterogeneity, connecting ROS, microtubules, and cell growth direction, and mechanical stress. I find that the microtubule arrangement is disrupted in ftsh4-5, with an increase in areas of dense microtubule signal, areas of intense microtubule crossover, and overall signal intensity as compared to wild type. These results suggest that the microtubules of ftsh4-5 are more highly bundled than wild type and are likely less able to reorient during development, which would affect averaging of growth direction. I also find that ftsh4-5 produces increased ROS after mechanical stress, to a greater extent than wild type. This result suggests that the elevated ROS levels in ftsh4 may be partially due to an over-active response to mechanical stress. These results are consistent with my hypothesis that a feedback loop controls robust development and suggest that the overactivity of this feedback loop may disrupt development, resulting in the ftsh4-5 phenotype.