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Scleroderma polyrhizum

[ Basidiomycetes > Boletales > Sclerodermataceae > Scleroderma . . . ]

by Michael Kuo

In my little Midwestern town, Scleroderma polyrhizum is Nature's way of getting back at urban development. We have a subdivision called "Heritage Woods," built by a developer in the 1970s who leveled acres of natural trees to build split-levels with prominently featured garage doors for middle-class white people ("Heritage") who planted ornamental, non-native, four-foot saplings to decorate their yards ("Woods").

But Scleroderma's Revenge has been popping up all over the place ever since. When young, the tough, baseball-sized mushrooms wreak havoc with lawnmower blades; in maturity they split and spread open, creating unsightly black lawn-sores near sidewalks--plump pustules on patiently preened promenades.

Here's to the dandelions, who will always come back! Here's to Pluteus petasatus, fruiting from buried roots by the dozens, years after the City has removed the tree ("What if my kid touches it?" "The dog ate one!" "How do I kill these mushrooms??!!"). Osama bin Laden has attacked New York; we'd better remove the "Virtual Tour" of the Charleston, Illinois water plant from the Internet, so he can't figure out how to poison us!

And here's to Scleroderma polyrhizum. Identifying features include the baseball-like stature and shape; the tough, thick skin; the hard, black interior that turns to dust in old age; the way the mushroom splits open and peels back (a little like the rays of a star); the smooth to pocked or pitted (but not prominently scaly) surface; and the habitat in grass and disturbed-ground settings.

Scleroderma geaster is a synonym; "Scleroderma polyrhizon" is also probably a synonym.

Thanks to Joanne Bilarczyk for collecting, documenting, and preserving Scleroderma polyrhizum for study; her collection is deposited in The Herbarium of Michael Kuo.


Ecology: Probably saprobic, but possibly mycorrhizal; growing alone, scattered, or gregariously in grass and in disturbed-ground settings; often appearing in urban settings; summer, fall, and early winter; widely distributed in North America.

Fruiting Body: 8-13 cm across before splitting and spreading; round or nearly round; very tough; partially submerged in the ground; surface when young fairly smooth, often covered with whitish down; with age becoming pocked, pitted, or minutely scaly in places, and usually covered with adhering soil and debris; often bruising reddish or yellowish when rubbed; with maturity splitting near the top and peeling back in irregular rays to expose the spore mass; skin to 5 mm thick or more, whitish but blushing pink when sliced; sometimes with white rhizomorphs attached to the base; odor not distinctive.

Spore Mass: Black to purplish black and hard at first, becoming dark brown and powdery; with whitish to pale yellowish threads interspersed.

Chemical Reactions: Fresh surface negative or slightly yellowish with KOH.

Microscopic Features: Spores 7-10 µ; round or nearly so; with very tiny spines (mostly under .5 µ); partially but not completely reticulate.

REFERENCES: (Gmelin, 1796) Persoon, 1801. (Fries, 1829; Saccardo, 1888; Coker & Couch, 1928; Smith, 1951; Guzmán, 1970; Smith, Smith & Weber, 1981; Weber & Smith, 1985; Arora, 1986; Phillips, 1991/2005; Lincoff, 1992; Metzler & Metzler, 1992; Sims, Watling & Jeffries, 1995; Miller & MIller, 2006.) Herb. Kuo 09170501, 01030801.

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Scleroderma polyrhizum

Scleroderma polyrhizum

Scleroderma polyrhizum

Scleroderma polyrhizum

Scleroderma polyrhizum

Scleroderma polyrhizum

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Kuo, M. (2006, February). Scleroderma polyrhizum. Retrieved from the MushroomExpert.Com Web site: