Skirted Stinkhorn

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Skirted Stinkhorn is an easily recognized stinkhorn mushroom. It is the only skirted stinkhorn in North America north of Mexico. It occurs in the United States from Maine to South Carolina, west to Minnesota and Tennessee, in Canada from Nova Scotia west to southern Ontario, and in Great Britain. There are also scattered reports from Europe, Asia, South Africa, Central America, northern South America, and the Pacific Northwest of North America. The reports from Brazil and South Africa are reliable. Those from Europe are suspected of being misidentifications of Phallus indusiatus.

Skirted Stinkhorn is found in summer and fall, alone or in small groups but not clustered (gregarious), in hardwood forests, landscaped areas, gardens, flower beds, and wood chips. It grows on the ground and obtains its nutrients from decayed wood (saprobic).

When the fruiting body first appears, it is whitish to purplish, egg-shaped or nearly round, 1¼″ to 3″ (3 to 8 cm) long, and ¾″ to 1½″ (2 to 4 cm) wide. The “egg” is attached to the substrate by thread-like, branched, white to purplish strands of mycelium (rhizomorphs). Inside the egg there is a brownish gelatinous layer, a dark olive-green spore mass, and all of the fully formed parts of the stinkhorn. As the stinkhorn expands the gelatinous layer mixes with the spore mass producing a slime.

Pressure from the expanding stinkhorn eventually causes the egg to rupture. In one or two days it produces a distinctly phallic structure with a stalk and thimble-like head. The rapid expansion is possible because all of the parts are fully formed and compressed inside the egg, and because the individual cells elongate, rather than new cells being produced. A net-like skirt (indusium) grows from the bottom of the cap.

The mature stinkhorn is cylinder-shaped and 2″ to 6¾″ (5 to 17 cm) long.

The head is broadly cone-shaped and 1¼″ to 2″ (3 to 5 cm) high. At first it appears smooth due to a thick covering of shiny, dark olive-green, spore-bearing slime (gleba). The slime has a strong, putrid odor, repulsive to humans but irresistible to flies, which feed on it, lay their eggs in it, and transfer spores when they fly to other stinkhorns. As it ages, the head develops a circular opening at the top that is surrounded by a white lip. As the gleba is carried off by flies and/or washed off by rain it reveals a whitish, deeply pitted and ridged, net-like (reticulate) surface.

The stalk is hollow, dry, white or whitish, 3″ to 5″ (8 to 13 cm) long, and ¾″ to 1¼″ (2 to 3 cm) thick. The surface is minutely sponge-like with 1 to 2 pit-like depressions per millimeter. At the base of the stalk there is a whitish to purplish, ¾″ to 2″ (2 to 5 cm) high cup (volva), the persistent remains of the egg.

The indusium hangs from the bottom rim of the head and grows slowly. It is white and has relatively small holes. At maturity it is 1¼″ to 2⅜″ (3 to 6 cm) long and flares slightly away from the stalk.

Summer and fall

Sources

24, 26, 29, 30, 77.

Index Fungorum and MycoBank both list Phallus duplicatus as a synonym of Phallus indusiatus. All other sources list Phallus duplicatus as a legitimate species with a shorter indusium and larger spores, and Phallus indusiatus having a range in the Americas extending north only as far as Mexico. This may represent an error in Index Fungorum introduced in 2019 then replicated in MycoBank.

Netted Stinkhorn

This is the “egg” taken the day before, 9/15/2022 at 9 am.

The next day, 9/16/2022. It had erupted from the egg sometime overnight and before 7 am.

Closeup of the cap and indusium.

Different angle with flies attracted to the stinkhorn.

Closeup of the cap showing the foul smelling gleba.

A bald faced wasp attracted to the stinkhorn.

Share your video of this fungus.

Location: Vetsch Park in La Crescent

The next day, 9/16/2022. It had erupted from the egg sometime overnight and before 7 am.

Location: Vetsch Park in La Crescent

This is the “egg” taken the day before, 9/15/2022 at 9 am.