Distribution of mechanical stress is not involved in regulating stipe gravitropism in Coprinus cinereus.

Removal of large segments of the apical part of the stipe of Coprinus cinereus (extending to about half its length) affected neither the ability of the stipe to show gravitropic bending nor its ability to compensate the curvature so induced and adjust to the vertical. However, gravitropic reaction time was directly proportional to the amount of stipe removed. Application of lateral loads of up to 20 g had no adverse effects on adjustment of the stipe to the vertical and continued vertical growth. It is concluded that sensing the distribution of extracellular mass and/or mechanical stress is unlikely to be a component of the control of gravitropic bending in C. cinereus stipes.