Associations between developmental stability, canalization and phenotypic plasticity have been predicted, but rarely supported by direct evidence. Architectural analysis may provide a more powerful approach to finding correlations among these mechanisms in plants. To investigate the relationships among the three mechanisms in architectural perspective, we subjected plants of Abutilon theophrasti to three densities, measured and calculated fluctuating asymmetry (FA), coefficients of variation (CV) and plasticity (PI) of three leaf traits, to analyze the correlations among these variables. As density increased, mean leaf size, petiole length and angle of most layers and mean leaf FA of some layers decreased (at both stages), CV of petiole angle increased (at day 50), and PI of petiole length and angle across all layers decreased (at day 70); leaf FA and CV of traits generally increased with higher layers at all densities. At both stages, there were more positive correlations between FA and CV at lower vs. high densities; at day 50, little correlation of plasticity with FA or CV was found; at day 70, more positive correlations between FA and PI occurred for response to high vs. low density than for response to medium vs. low density, and more positive correlations between CV and PI occurred at lower vs. high densities. Results suggested that developmental instability, decreased canalization and plasticity can be cooperative and the relationships between decreased canalization and plasticity are more likely to be positive if decreased canalization is due to vibrant growth rather than stressful effects. The relationships of plasticity with developmental instability differed from its relationship with decreased canalization in the way of variation. Decreased canalization should be more beneficial for possible plasticity in the future, while canalization may result from already-expressed plasticity.