ballistospore, in fungi, a spore forcibly propelled from its site. The basidiospores of the mushrooms, produced on the gills and on the walls of the spores, are ballistospores. They are shot a very short distance from the vertical walls of the fruiting structure and then drift down. In other fungi, including certain slime molds, they are propelled in other directions by various mechanisms and are sometimes projected a considerable distance from the fruiting structure.