Agaricus micromegathus
What You Should Know
Agaricus micromegathus is a small grass mushroom. It is recognized by a cap with pinkish to purplish fibrils concentrated at the disc. With age, these become brownish and frequently tinged yellowish where handled. Habitat solitary to scattered, sometimes in arcs in the grass; fruiting in late summer in watered areas or soon after the fall rains; uncommon.
Agaricus micromegathus Mushroom Identification
Cap
2-4cm across, broadly convex to convex-truncate when young, becoming depressed centrally when old nearly flat; dry, innately fibrillose, fibrils pinkish red, darkening to gray-brown or dingier, forming appressed to slightly repent fine scales about 0.2cm long and 0.1-0.2cm wide, background whitish to buff.
Flesh
Up to 0.4cm thick; white, unchanging or becoming yellowish, in stem white, to salmon-orange when old, (Kerrigan), thick, white, unchanging, (but also notes all parts of sporophore staining deep saffron-yellow where bruised), (Hotson), thin, fragile; "white, unchanging or bruising yellowish".
Gills
Free, close, up to 0.3cm broad, grayish when young, soon pinkish, crowded, broad, thin; white for a long time, becoming pink then purplish gray, free at maturity, close.
Stem
2.5-3cm x 0.2-0.8cm, equal or very slightly bulbous, narrowly stuffed-hollow, cavity 0.05-0.1cm broad; white, becoming orangish when old or when bruised; finely fibrillose when young, bald when old.
Veils
Sometimes appendiculate, more usually forming a pendant (to intermediate-type), subapical to supramedian white ring, flaring 0.2-0.4cm, partial veil white, loosely interwoven, universal veil a narrow denser zone on ring undersurface, soon becoming orangish, also leaving deciduous fibrils on the stem.
Odor
Almond, distinctly sweet (anise-like or almondy).
Taste
Pleasant and nutty – almond-like.
Spore Print
Chocolate brown.
Microscopic Features
Spores (3.8)4.6-4.9(5.6) x (3.0)3.5-3.8(4.1) microns, elliptic to broadly elliptic, dark brown, hilar appendix fairly prominent, germ pore not evident; basidia 4-spored, 21-25 x 5-7 microns, cylindroclavate, sterigmata 2-3 microns long; cheilocystidia not observed, gill margin fertile.
Agaricus micromegathus Look-Alikes
Agaricus comptulus
Another small, anise-odored species is found in grass, but it has a cream-colored cap. Like Agaricus micromegathus, it yellows slowly where injured.
Agaricus semotus
Can be distinguished by somewhat larger size and habitat preference.
Agaricus diminutivus
Is distinctive because of its unusually small size and slender stature. Except for gill color, it could easily be confused for species of Lepiota.
Sources:
Photo 1 - Author: leptonia (Attribution-NonCommercial 4.0 International)
