Dispersal of fungal spores by gravity currents

Spore is an asexual reproduction unit of fungi, also often found in plant kingdom. The physics behind spore dispersal of the Basidiomycete fungi or more known as mushroom will be the main focus of our study in this paper. We hypothesize that the spore dispersal is driven by the gravity current under the mushroom cap due to the density difference between the spore air laden and ambient air. Here we show that the gravity current is present when the gap under the mushroom cap is small i.e.  12 mm. We validated that the dispersal length is inversely proportional to the shorter dimension of the mushroom cap and directly proportional to the gap under the mushroom cap. Furthermore, our results demonstrate that there are other possible contributors beside gravity current that help the spore dispersal. We anticipate our work to be a starting point for more study in finding the other possible driving force of the spore dispersal. This is important as we might be able to understand why mushrooms excel at spore dispersal. Two possible future works are: looking at the temperature gradient of the air under and surrounding the mushroom cap, and looking at the role of water evaporation from the mushroom cap. Dispersal of fungal spores Spore dispersal plays a vital role in the survival of the Basidiomycete fungi or more known as mushroom because they are completely immobile. Wind is widely known to be the main driving force of spore dispersal of Ascomycete fungi as the aerial hyphae grows upward thus completely leaving them exposed to wind. In contrast, Basidiomycete fungi cannot rely on the wind as they often do not grow tall enough to avoid the boundary layer of still air next to the ground or under the mushroom cap. Furthermore, they also often grow on top of each other thus only leaving small gaps under the cap. These two features are the main obstacles causing the spores fail to disperse further from its parent fruiting body. In this paper, we will take a look at how does Basidiomycete overcome these obstacles with a hypothesis that gravity current is the driving force for the spore dispersal.