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Agrocybe pediades

[ Basidiomycetes > Agaricales > Bolbitiaceae > Agrocybe . . . ]

by Michael Kuo

This common lawn mushroom frequently comes up after rains in early summer (or nearly year-round in warmer areas), and is also found in pastures and meadows. It has a thin cap, a skinny stem, and a medium brown spore print. Several features of Agrocybe pediades are fairly variable, including its colors and the size of its spores. It is often treated as a species "cluster" in field guides, but recent investigators have been leaning toward defining it as a single, variable species. Agrocybe semiorbicularis, once separated from Agrocybe pediades on the basis of its slightly larger spores and thinly sticky cap, has now been synonymized.

Agrocybe pediades has a partial veil, but it is so ephemeral that you will need to be looking at buttons the size of pencil erasers to see it. Within a few hours, all evidence of the veil has usually disappeared. Collections I have made in California, Colorado, and Illinois have demonstrated a color change to red or pink when a drop of KOH is applied to the cap surface; other Agrocybe species I have tested show no color change or a change to dull yellow.

Description:

Ecology: Saprobic; growing alone or gregariously in lawns, meadows, and other grassy areas (and sometimes on wood chips, dung, or sand); summer (but nearly year-round in warm climates); common and widely distributed in North America.

Cap: 1-4 cm; convex, broadly convex, or nearly flat; yellow brown or paler; smooth; dry or sticky; occasionally with whitish partial veil remnants on the margin.

Gills: Attached to the stem; pale grayish brown becoming brown to rusty or cinnamon brown in maturity; close or, in my experience, often nearly distant; when young covered by an ephemeral white partial veil.

Stem: 2-6 cm long; 1.5-5 mm thick; more or less equal; smooth; colored like the cap; sometimes twisted-grooved.

Flesh: Pale and thin.

Taste: Not distinctive or mealy; odor not distinctive or mealy.

Spore Print: Brown.

Chemical Reactions: Cap surface red to pink with KOH.

Microscopic Features: Spores 9-13 x 6.5-8 µ; smooth; elliptical but slightly truncated. Cystidia 30-70 x 8-15 µ; fusoid-ventricose with pointed or slightly swollen tips.

REFERENCES: (Persoon ex Fries) Fayod, 1889. (Smith, Smith & Weber, 1979; Arora, 1986; Phillips, 1991/2005; Lincoff, 1992; Roody, 2003; McNeil, 2006.) Herb. Kuo 06019512, 06120201; 08060501; 05020601; 05120607.

Further Online Information:

Agrocybe pediades at MykoWeb
Agrocybe pediades at Roger's Mushrooms
Agrocybe semiorbicularis at Roger's Mushrooms

 

Agrocybe pediades

Agrocybe pediades

Agrocybe pediades

Agrocybe pediades

Agrocybe pediades

Agrocybe pediades



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Kuo, M. (2006, September). Agrocybe pediades. Retrieved from the MushroomExpert.Com Web site: http://www.mushroomexpert.com/agrocybe_pediades.html