Panaeolus semiovatus (Sowerby: Fries) S. Lundell & Nannfeldt
Fungi Exsiccati Suecici 11-12: 14 (no. 537). 1938.

Common Name: none

Synonyms: Panaeolus seperatus (Linnaeus: Fries) Gillet; Annelaria semiovata (Sowerby: Fries) Pearson & Dennis

• Pileus

  Cap 4.0-6.0 cm broad, ovate, then paraboloid, becoming hemispheric to broadly obtuse-conic, rarely expanding to convex; margin overlapping the gills, incurved, decurved in age; surface viscid when moist, drying glossy, wrinkled, cream, to pale-tan, darker at the disc, gradually fading at maturity; context white, unchanging, soft, up to 7.0 mm thick at the disc, gradually tapered towards the margin; odor not distinctive, taste "fungal."

• Lamellae

  Gills ascending-adnate to adnexed, close, broad, up to 10 mm in width, dingy greyish-tan when young, the edges lighter than the faces, minutely fringed with a hand lens, becoming mottled blackish, blackish overall in age; lamellulae in two series.

• Stipe

  Stipe up to 15 cm long, 0.5-1.0 cm thick, slender relative to the cap, equal except enlarged at the base, the core narrow, stuffed; upper surface conspicuously pruinose-striate, cream-colored, lower portion appressed fibrillose, colored like the cap or dingy yellowish-tan, dry to lubricous when moist; stipe base when fresh, covered with a white pubescence, drying down and becoming tomentose; partial veil cottony-fibrillose, white, forming a fragile superior annulus, at maturity flattened to the stipe, blackened by spores.

• Spores

  Spores 15.5-20.5 x 9.0-12.5 x 10.0-11.0 µm, broadly elliptical in face-view, slightly narrower in profile, thick-walled, smooth, germ pore eccentric, the apex truncate, hilar appendage inconspicuous; spores grey-black mounted in water; spore print black.

• Habitat

  Solitary or in small groups on horse and cow dung; fruiting throughout the mushroom season; occasional.

• Edibility

  Questionable. (Arora: "edible according to most sources"; Jordan: "inedible"; McIlvaine: "excellent in substance and flavor"; Miller: "poisonous-hallucinogenic"; Phillips: "not edible"; Smith & Webber: "edible and good"; Stamets: "conflicting reports on the edibility of this species")

• Comments

  A large, statuesque mushroom, Panaeolus semiovatus is recognized by a viscid, cream-colored, wrinkled cap and annulate stipe. Its preference for fruiting on dung, particularly horse dung is shared with a smaller, more common cousin, Panaeolus papilionaceus. The latter is distinguished by a rust-brown to grey-brown, nonviscid cap, lack of annulus and a partial veil that leaves fragments on the cap margin rather than a ring. Unrelated but somewhat similar in appearance to Panaeolus semiovatus is Volvariella speciosa. It also has a light-colored, viscid cap when moist, but doesn't occur on dung. Other differences include the presence of a volva, lack of an annulus, and salmon-pink spores.

• Other Descriptions and Photos
  • Illinois Mycological Society: Panaeolus semiovatus (D, I, & CP)
  • BioImages: Panaeolus semiovatus (D & CP)
  • First Nature: Panaeolus semiovatus (D & CP)
  • Eleanor Yarrow: Panaeolus semiovatus (CP)
  • R.A.Chilton: Panaeolus semiovatus (CP)
  • Arora (1986): p. 355 (D), p. 357 (P)
  • Breitenbach & Kränzlin (v. 4): sp. 318 (D, I, & CP)
  • Jordan: p. 239 (D & CP)
  • Lincoff: p. 603 (D), pl. 20 (CP)
  • Miller: sp. 191 (D & CP) [as Panaeolus seperatus]
  • Orr & Orr: p. 172 (D)
  • Phillips: p. 206 (D & CP)
  • Smith & Weber: sp. 223 (D & CP)

  (D=Description; I=Illustration; P=Photo; CP=Color Photo)