Printing101 - All about mushroom spore prints

You can also get spore prints from the other fungi that release their spores forcibly. The spores may be released actively or passively. In the former the fungus, through its own actions, ejects the spores from the basidia or asci with considerable force. In the latter the fungus relies on some other agent to release the spores from the fruiting body. The agents are varied - wind, impact, water, insects. Note that after the initial release, some other agency may be responsible for further dispersal of the spores. When a spore is mature it is forcibly shot from the basidium, into the air space between the gills. While the spore is ejected horizontally with considerable force (up to 25,000 times the force of gravity), air resistance stops the spore in a fraction of a millimetre. The air in the space between two gills is still, so after coming to a stop the only influence on the spore is gravity and the spore falls downward.

Once the spore has fallen below the bottom edge of the mushroom cap, and is clear of the gills, it strikes air that is not still. Even on what looks like a windless day, there are always slight breezes. While a human may not feel them, they are usually strong enough to be felt by a spore that is only about a hundredth of a millimetre long. These micro-breezes may pick up the spore and carry it higher into the air and away from the parent mushroom. The spore may come to rest a metre or a kilometre or even further away from the mushroom.