While up in Lockett Meadow last weekend, I came across a cup fungus of the genus Peziza. This rubbery brown fruiting body superficially resembles a wood-ear fungus, Auricularia auricula, but is much thinner and flimsier. It is an ascomycete that is actually more closely related to the morel (Morchella spp.)
As an ascomycete, its reproductive spores are produced in sacs called asci at the surface of the brown lining inside the cup. Many ascomycetes, including Peziza, have evolved highly sophisticated spore dispersion mechanisms. These typically involve a violent dehiscence of the ascus and ejection of the spores into the air in response to a stimulus such as a raindrop or change in air pressure. This clever adaptation ensures that the spores will be discharged at a time when the chance of successful spore dispersion is maximal.
For fun, I sat on the log beside the fungus and put my phone in video mode. Sure enough, whenever I blew on the brown cups, they would respond with a noticeable discharge. You’ll see in the video below that these are not loose spores on the lining of the cup that are immediately blown up into the air. Instead, there is a lag time of a second or two, at the end of which the dehiscence of the asci is completed, and the spores are ejected several centimeters upwards like a puff of smoke.
You can see this interesting effect even more clearly in this similar video found on YouTube: