How Do Inflorescences of Lupinus polyphyllus (Fabaceae) Re-Establish Their Position after Artificial Bending?

The correct position of the inflorescence is vital for pollination success. Many plants have physiological reorientation mechanisms based on the effects of the hormone auxin, which is secreted in apical meristems and induces negative gravitropism. The younger the inflorescence is, the more important it is to restore its vertical position in the fastest possible way to maximize pollination success. Thus, we investigated the effect of the absence of inflorescence’s apical part and inflorescence age on its reorientation and position of bending point. As an object of investigation, the invasive Lupinus polyphyllus was chosen, since the position of the flowers along the axis makes the plant convenient for manipulation. Removal of the apex does not influence the restoration of orientation relative to the ground. Younger inflorescence tends to have a greater part of them reoriented. The reoriented part of the inflorescence mainly contained unopened or partly opened flowers at the moment of the initial bending by the experimenters.