What You Should Know
Stropharia pseudocyanea is one of the very few blue-green fungi. The caps, initially bell-shaped, flatten and turn paler from the center. What makes this species instantly recognizable and truly memorable is not so much its admittedly attractive appearance but its distinctive smell - exactly like freshly ground pepper
It is inedible and may even be poisonous. Some of the Stropharia species can certainly cause very unpleasant gastrointestinal symptoms.
Other names: Peppery Roundhead.
Stropharia pseudocyanea Mushroom Identification
0.8-2cm across, initially obtusely conic with incurved margin, soon convex and usually obtusely umbonate to subumbonate; somewhat hygrophanous, eye blue to sky blue in buttons, becoming glaucous to glaucous sky blue and sometimes pale brownish centrally, fading in areas to greenish glaucous; viscid, opaque, the margin with minute, ephemeral, whitish to glaucous, floccose, hanging veil remnants, (Redhead), 1-3cm across, "conic-convex, expanding to acutely to bluntly umbonate"; "whitish with azure to bluish green tinges, fading to straw or cream-colored"; "viscid from a separable gelatinous pellicle", margin adorned with partial veil remnants, (Stamets)
Colored as cap, (Redhead), "bluish-green, fading to azure, then pale bluish-green" and eventually straw-colored, (Stamets)
Gills Adnexed, moderately spaced, moderately sized to moderately broad, with up to 3 tiers of subgills; whitish to buff becoming hazel-tinted when old, edges whitish; edges minutely crenulate [scalloped], (Redhead), adnate; pale fawn to purplish; with tooth-like edges, (Stamets)
2.1-6cm x 0.13-0.22cm, "equal or sometimes with a slightly swollen base", hollow, fibrous; colored as cap; dry, minutely floccose scaly up to a median or superior, distinct to indistinct ring zone when in prime condition, finely powdered and striate at the top, with "prominent white mycelial strands and mycelium basally", (Redhead), 3.5-7cm x 0.2-0.5cm, equal, slim, flexuous [wavy], soft, easily breaking; bluish green to azure blue to straw-colored.
Cap margin with minute, ephemeral, whitish to glaucous, floccose, hanging veil remnants, stem scaly up to a median or superior, distinct to indistinct ring zone when in prime condition, (Redhead), partial veil membranous, adorning cap margin and leaving a membranous ring on stem that degrades into a ring zone (Stamets)
Odor and Taste
Not distinctive, usually rather strong, peppery.
Spores 8.2-9.5 x 4.8-5.5 microns, narrowly almond-shaped to oval, "smooth, with a slightly thickened wall and a minute germ pore or thin apical area"; basidia 4-spored, 26.5-28 x 6.5-7.0 microns, cylindric-clavate, with clamp connection; pleurocystidia 39-42 x 9-10 microns, "only slightly projecting, obtusely clavate to mucronate or rostrate, with a central refractive grainy body, the walls thin, smooth", cheilocystidia 29-37 x 5-8 microns, "mostly subcapitate to capitate and narrowly ventricose, the neck sometimes slightly undulating", thin-walled, smooth, with homogeneous contents, colorless, (Redhead), spores 7-9 x 4-5 microns, elliptic; basidia 4-spored, cheilocystidia 24-44 x 4-8 x 4-5 microns at apex when narrowing or 6-12 microns when swollen, capitate-clavate to lageniform capitate, (Stamets)
Stropharia pseudocyanea Look-Alikes
Is a larger blue-green mushroom and its cap scales are persistent; it has reddish-brown gills with white edges. This species is uncommon in Britain and Ireland. It does not have a peppery odor.
Is a larger, fairly common blue-green roundhead without a peppery odor.
Is also blue-green but does not have a slimy cap with scales; it has a strong odor of aniseed.
Stropharia pseudocyanea Taxonomy and Etymology
Although this little blue mushroom has been known to science for something like two centuries, its separation from Stropharia aeruginosa had not been clearly defined until it was described in a 1908 posthumous publication by an American mycologist Andrew Price Morgan (1836 - 1907) and given its currently-accepted scientific name Stropharia pseudocyanea.
The basionym dates from 1823 when French naturalist John Baptiste Henri Joseph Desmazières (1786 - 1862) described this pretty little mushroom and gave it the binomial scientific name Agaricus pseudocyaneus. (In the early years of fungal taxonomy and naming, most gilled mushrooms were initially placed in the genus Agaricus, since slimmed down by transfer of the majority of former Agaricus species to other newer genera, including of course Stropharia.)
Stropharia, the genus name, comes from the Greek word strophos meaning a belt, and it is a reference to the stem rings of fungi in this generic grouping. The specific epithet pseudocyanea means nearly blue, and it refers to the blue-green coloring of these grassland mushrooms.
Stropharia pseudocyanea Synonyms
Agaricus pseudocyaneus Desm.
Agaricus albocyaneus Fr.
Stropharia albocyanea (Fr.) Quél.
Agaricus worthingtonii Fr.
Stropharia worthingtonii (Fr.) Sacc.
Photo 1 - Author: Chris Herrera (The Mushroom Whisperer) (Creative Commons Attribution-Share Alike 3.0 Unported)
Photo 2 - Author: Josip Skejo (Creative Commons Attribution 4.0 International)
Photo 3 - Author: Strobilomyces (Creative Commons Attribution-Share Alike 3.0 Unported)
Photo 4 - Author: Tom (LanLord) (Creative Commons Attribution-Share Alike 3.0 Unported)