SUMMARYAirborne basidiospores released from field-produced basidiocarps ofCryptoporus volvatuswere collected by placing a funnel, equipped with a collection vial, below each of seven developing basidiocarps. Spores collected in the vials were counted every 7 to 11 da until spore release ceased (average 71 da). Spores released per basidiocarp averaged 2.5×109(4.0×108/cm2of pore surface), comparable to spore production by other polypores whose spores are wind disseminated. Spore-release patterns were not affected by rainfall. The unique subtending volva, long considered an adaptation for insect dispersal, appears to be a xerophytic adaptation which protects the hymenophore from desiccation. The volva allows production of airborne spores during the periods of low rainfall and relative humidity often associated with bark-beetle flights in the areas of western North America where this fungus is most common.