Volvariella volvacea

Key to Gilled Mushrooms Key

This is a key to gilled mushrooms, that is, mushrooms having a definite cap with a fertile surface consisting of gills. The fruiting body usually also has a stem, although that may be lateral or absent (usually, then, the mushroom is growing from wood). You can use this key to identify mushrooms that you find.

Agaricales Order

With a saccate volva, or cup, at the base of the stalk
On a variety of substrates
Cap typically (but not in this picture) bluntly conical, not umbonate or convex

Big Volvariella Section

Cap typically more than 2" across

Volvariella volvacea (Bulliard: Fries) Singer

Here are the characters that distinguish this species from the others in its group. For its more general characters, see higher up on the page.
If there's just a few words or a microscopic feature here, a more thorough description can be found above.

Diagnosis

Cap up to 4" across; brownish grey; with blackish virgate streaks
Volva large; brownish, at least towards the top
On organic debris in greenhouses or other situations where it can be warm all year

Microscropic Characters

Spores 7-10 x 4.5-7 µm
Pleurocystidia 52-105 x 7.5-15 µm
Cheilocystidia 30-60 x 8-18 µm

Comments

This is the "straw mushroom", cultivated in tropical Asia and only common in tropical climates. But it can occur wherever it gets shelter somehow from the winter
My dad and I were fortunate enough to find tremendous fruitings several years in a row in New York, on a huge leaf-pile where a hospital dumped all their yard waste. Apparently the heat of decay kept the interior of the pile warm enough for this mushroom to thrive

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Volvariella volvacea

Fruiting body containing fibers (usually in the stalk)

Spores pink or reddish

Gills free Often growing on wood