Responses of agaric fruit-bodies to light and gravity: growth straight downward in response to light from below

Fruit-bodies of Agaricales are known to show positive phototropism during the early stage of development, but negative gravitropism at the later stage after the onset of basidiospore formation. However, when exposed to light from below, the fruit-bodies ofTephrocybe tesquorum andCoprinus spp. grew downward through all stages of development, even after the onset of basidiospore formation. Primordium formation, fruit-body development and basidiospore formation were not disturbed under such conditions. In these downward-growing fruit-bodies, gills stood straight upward. InT. tesquorum, caps often became swollen and stipes sometimes became twisted anticlockwise, contrary to those in light from above, while such behaviours were not observed inCoprinus spp.