Major Groups > Gilled Mushrooms > Pink-Spored > Entolomatoid Mushrooms > Entoloma quadratum


Entoloma quadratum

[Basidiomycota > Agaricales > Entolomataceae > Entoloma . . . ]

by Michael Kuo

This bright, distinctive little mushroom, sometimes called the "unicorn mushroom" in field guides, is found east of the Rocky Mountains, usually in conifer woods. When fresh, its colors are bright salmon orange, but it fades with age; older specimens can be confused with the similar, but yellow, Entoloma murrayi. Under the microscope, Entoloma quadratum features cube-shaped spores, vascular hyphae, and inconspicuous cheilocystidia.

Entoloma quadratum is sometimes called "Entoloma salmoneum," but the latter species was synonymized by Horak (1976) after "some hesitation" and trepidation, because in "[f]ormulating this opinion we expect criticism from various quarters. However, comparing the results of the numerous collections studied we could not find convincing characters to separate these taxa." More recently, Noordeloos and Hausknecht (2007) confirmed Horak's position based on type studies and additional collections.

Inocephalus quadratus and Nolanea quadrata are also synonyms.


Ecology: Saprobic; growing alone or scattered in in moss under conifers (but occasionally reported under hardwoods); frequently found on rotting, moss-covered conifer logs; summer and fall; apparently widely distributed in eastern North America (the illustrated and described collections are from northern Michigan).

Cap: 1-3 cm; conical or bell-shaped, with a pointed center; bald; bright salmon orange, fading to orangish or dirty yellowish; sometimes discoloring greenish to olive in places; sticky when fresh; translucent-lined.

Gills: Narrowly attached to the stem; distant or nearly so; colored like the fresh cap and remaining so longer than the cap; short-gills frequent.

Stem: 4-10 cm long; 2 mm thick; hollow; fragile; bald; colored like the cap, or with a greenish tinge; with white to pastel orange basal mycelium.

Flesh: Thin; fragile; colored like the cap, or paler.

Odor and Taste: Not distinctive.

Chemical reactions: KOH negative on cap surface.

Spore Print: Pink.

Microscopic Features: Spores 8-10 µ; cuboid; square in profile; hyaline; smooth. Pleurocystidia absent. Cheilocystidia often absent; when present clustered, clavate, to 85 x 15 µ. Pileipellis a cutis with granular intracellular pigment. Refractive vascular hyphae present. Clamp connections rare.

REFERENCES: (Berkeley & M. A. Curtis, 1859) Horak, 1976. (Peck, 1872; Saccardo, 1887; Kauffman, 1918; Hesler, 1967; Horak, 1975; Smith, Smith & Weber, 1979; Arora, 1986; Phillips, 1991/2005; Lincoff, 1992; Barron, 1999; Halling & Mueller, 2005; McNeil, 2006; Noordeloos & Hausknecht, 2007.) Herb. Kuo 09029506, 09040201.

This site contains no information about the edibility or toxicity of mushrooms.


Entoloma quadratum

Entoloma quadratum

Entoloma quadratum

© MushroomExpert.Com

Cite this page as:

Kuo, M. (2014, February). Entoloma quadratum. Retrieved from the MushroomExpert.Com Web site: