Sphaerobolus stellatus has one of the most unusual spore dispersal mechanisms: its base pops up and quickly flings a glob of spores into the air. The fungus forms tiny (no more than 3mm across) star-shaped mushrooms in mulch, which can cause problems for homeowners when the spore globs glue themselves to cars, siding, and the like. S. stellatus’s unique spore dispersal strategy has resulted in a variety of common names, including: “Artillery Fungus,” “Cannonball Fungus,” “Cannon Fungus,” “Sphere Thrower” (which is a literal translation of its Latin name), and “Shotgun Fungus.”
mushrooms with an earthstar morphology
In celebration of last night’s meteor shower, I have chosen to discuss a little star that can be found during the day in some parts of North America: the earthstar Geastrum fornicatum. Earthstars are all very similar: they have a puffball-like center surrounded by several pointed “arms,” grow on the ground, and are brownish in color. fornicatum can be distinguished from most other North American earthstars because its arms lift the circular center well above the ground. For this reason, it is called the “Arched Earthstar” (“fornicatum” actually translates to “arched”). G. fornicatum is most commonly found in Southwestern North America, but can be found elsewhere around the world.
Note: this is an archived post. You can read the current version of this post here. Happy New Year! To celebrate, I decided to use some fungal cannon fire to start 2016 off with a bang! Although it is tiny, Sphaerobolus stellatus gets just about as close as a fungus can to actually being a firework. The tiny, star-shaped fruiting bodies are designed to launch a spherical sac of spores high into the air. This unique spore dispersal strategy has resulted in a variety of common names, including: “Artillery Fungus,” “Cannonball Fungus,” “Cannon Fungus,” “Sphere Thrower” (which is a literal translation of its Latin name), “Shotgun Fungus,” “Shooting Star,” and “Bombardier Fungus.”
This mushroom is one of the most common earthstars and can be found all across the globe. Geastrum saccatum does not have an official common name, although the name “Rounded Earthstar” is occasionally used. Most of the time, it is just called “an earthstar.” Most North American earthstars look very similar to saccatum, but it is possible to tell them apart without running for a microscope.
In celebration of Independence Day, I will be discussing the festively-shaped earthstars. Earthstars are characterized by a puffball-like sphere surrounded by a star-shaped base. The earthstars all have a three-layered peridium (the surface that covers the developing spore tissue). At maturity, the two outer layers split into rays and peel back to form the star-shaped base. The endoperidium (interior layer) then develops an ostiole (pore) ringed by a peristome through which spores are discharged. Earthstars are included in the gastromycetes, which all form their spores internally and cannot forcibly discharge their spores. Instead, like the puffballs, spores of earthstars are forced out of the pore when raindrops land on the endoperidium. All earthstars have capillatum, a network of cells designed to help spores move to the pore when a raindrop strikes the mushroom. If you cut open an earthstar you will find that it looks nothing like the interior of...