Puffball Lycoperdon sp. releasing spores
Spore discharge from puff-balls of the Lycoperdon type (Agaricaceae) can be brought about by impact of water drops on the flattened papery top of the endoperidium (the inner of the two layers into which the sack that encloses a mass of spores is divided).
Raindrops of 1 mm. diameter or over, and rain-drip from trees are adequate to operate the mechanism. Analysis of the operation by ultra-high-speed photographs have shown that the puff reaches a height of a centimeter in approximately one-hundredth of a second after impact. The velocity of the puff on emerging from the ostiole (aperture) is of the order of 100 cm/sec.
The endoperidium (sack) is normally water-proof and ejection continues under humid conditions. Estimates, made from meteorological data, show that a fruit body must be operated many thousands of times in a season.
Photo credit: ©Marco Bertolini | Locality: unknown