A recent paper has revealed yet another ecological function fungal spores may provide, other than the passing of genetic information to subsequent generations. Maribeth Hassett and her team found that airborne spores released from higher fungi can actually kick start the cohesion of water vapor into water droplets on a massive scale. These fungal structures have been present in Earth’s atmosphere for over a billion years, and until now, may have been unknowingly driving rain events.

To understand how a fungal spore may act as a nucleus for condensation, we must first understand how these spores function inside of the fungus. Basidiospores released by gilled and poroid basidiomycete fungi have a fascinating mechanism of initial discharge. The Albert Einstein of mycology, A. H. R. Buller (1874–1944) first described this mechanism in 1922, nearly 100 years ago! First, a droplet of water forms on the slightly protruding hiller appendix. This appropriately named Buller’s droplet accumulates more and more water, while a separate droplet which is more like a blob of water also grows in size. When contact between the Buller’s droplet and the adaxial blob occurs, the water from the Buller’s droplet rushes over the surface of the spore and the spore’s center of gravity is rapidly manipulated. This change in center of gravity generates enough force to displace the spore from the basidium, where it can fall down the gill or pore surface to hopefully catch a rising air current.