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Fall 2011

Urban Jungle

The changing natural world at our doorsteps | Illustration and text by Patterson Clark      

October 25, 2011

Stinkhorns: Rank mushrooms from the mulch

A wet autumn provokes the emergence of mushrooms, the most visually startling of which are the stinkhorn fungi.

Phallus rubicundus commonly occurs in sun-drenched wood-chip mulch, where its mature fungal threads produce an egg-shaped structure at ground level. In the early morning an orange stalk rises from the "egg." The spongy fruiting body lasts for only a few hours, usually collapsing by noon.

The stalk's cap exudes a brown, spore-laden slime that discharges a fetid odor, which attracts flies.

The slime sticks to the feet of the insects, which spread the fungus when they land on damp mulch. But a more effective form of spore dispersal begins when the flies feverishly sponge up the sticky, stinky syrup, consuming as much as 80 percent of their body weight in stinkhorn slime in a single day. The putrid breakfast doesn't sit well with a fly's digestive system. When a bout of diarrhea ensues, intact stinkhorn spores make their exit. Each resulting fly speck can contain more than 22 million stinkhorn spores.

P. rubicundus may employ hapless flies to spread itself locally, but the fungus has found an even more effective vector in human commerce. The transport and sale of wood chips has rapidly expanded the stinkhorn's range from the southern United States into the Northeast and upper Midwest.

The mushroom is not edible.

Phallus rubicundus, a stinkhorn fungus.

SOURCES: Mushroomexpert.com, Journal of Mycology, University of Hawaii Press