THE methods by which the spores of fungi are dispersed are both interesting and varied. Normally the spores are small and can travel long distances by air, and such distribution is only prevented by the natural barriers of mountains and seas. Small areas of water usually form no hindrance to travel.
The normal method of dispersal of spores of toadstools is by means of air-currents. The spore-bearing surface forms a lining to the gills on the underside of a toadstool and the spores are first shot from the surface into the tiny space between neighbouring gills. The spore then begins to fall vertically under the influence of gravity until outside the
region of the cap where it is taken up by air-currents. It will be seen that it is important for a toadstool to maintain a perfectly erect, otherwise a spore on its downward journey might foul a portion of an adjacent gill. The discharge of spores from an ordinary toadstool may continue night and day for a week or more.
Some of the hard bracket-fungi which grow out like shelves from the sides of trees are perennial and instances are known where a fungus has developed year after year in the same place for over eighty years. In fungi of this type the spore discharge may proceed continuously for perhaps a month every year. The total number of spores discharged reaches colossal figures. The number of spores that may be produced by a common mushroom averages about fifteen million million. In some fungi even higher figures than these are obtained, figures with such amazing rows of noughts that they seem to have strayed from an account of the national debt.