In both of the two falls we've been active at the field station (2007 and 2008), we've been lucky enough to come across giant puffballs Calvatia gigantea (or Langermannia gigantea - I'm no mycologist).

These large fungi easily reach 1 foot in diameter at the field station.  We find them mostly on the forested slopes.  In 2007, we found them starting around October 16th and persisting through mid-November.  I'm not sure if they were coming up earlier in 2008 or if I just spotted them sooner as a result of spending more time at the station.  It is notable that on the Zoology field trip to the Cleveland Metroparks Zoo we spotted some puffballs coming up in some of the planting beds on October 4th, about 180 miles further north. 

Puffballs are a type of mushroom, what the mycologists refer to as a Basidiomycota.  On most mushrooms, spores are produced on structures called basidia which line the edges of the many gills on the underside of the mushroom.  Each basidium produces 4 spores; in most cases the spores drop out of the bottom of the mushroom and are carried on the breezes.  When the spore settles it germinates and grows into a long threadlike mycelium; this is the business part of the fungi and it grows by digesting materials decaying in the soil.  Eventually, two compatible mycelia meet, fall in love, and fuse to form dikaryotic strands that bunch together to form the fruiting structure - a mushroom or puffball.

The puffball has a unique spore dispersal strategy.  Within the spongy interior, the spores are produced by the trillions.  Eventually, the puffball dries and hardens to the point where it is a papery sac filled with trillions of spores.  When an animal comes along and steps on or bites into the puffball the spores are ejected forcibly.  For small puffballs this can even be accomplished by the impact of falling raindrops.

When it is younger and the flesh is firm the puffball is edible. An excellent web page on edible fungi can be found here:

http://americanmushrooms.com/edibles3.htm

Be aware that mature puffballs are not edible, and that there are several other fungi that look a lot like a puffball when the puffball is young - do not eat any wild fungi without first consulting a reputable guide.

http://botit.botany.wisc.edu/toms_fungi/aug98.html

http://botit.botany.wisc.edu/toms_fungi/calvatia.html

Below, 2 views of the same puffball.

October 10, 2008

October 21, 2008