What You Should Know
Panaeolina foenisecii is a very common and widely distributed little brown mushroom often found on lawns. In 1963 Tyler and Smith found that this mushroom contains serotonin, 5-HTP and 5-hydroxyindoleacetic acid. In many field guides, it is erroneously listed as psychoactive, however, the mushroom does not produce any hallucinogenic effects.
It is sometimes mistaken for the psychedelic Panaeolus cinctulus or Panaeolus olivaceus both of which share the same habitat and can be differentiated by their jet black spores. This is probably why Panaeolina foenisecii is occasionally listed as a psychoactive species in older literature.
Crucial identifying features for Panaeolina foenisecii include its small size and habitat in the grass, along with the dark brown to purplish brown spore print, the lack of a ring or other evidence of a partial veil, and the "hygrophanous" cap: as the cap loses moisture and begins to dry out, its color changes rather dramatically. The result is that one finds many specimens in the process of transforming their colors, with different tones in distinct areas.
Other names: Mower's Mushroom, Haymaker, Brown Hay Mushroom.
Panaeolina foenisecii Mushroom Identification
Saprobic; growing alone to gregariously on lawns, in meadows, and in other grassy areas; widely distributed in North America, but apparently less common in the southeastern states (judging from online herbarium records); late spring, summer, and fall, or overwinter in warmer climates.
1–3.5 cm; widely conical or bell-shaped, becoming convex or nearly flat; bald; hygrophanous; dark brown, changing to pale grayish brown, tan, or buff—or with bands of these shades when in the process of drying out; often splitting radially with old age; the margin becoming finely lined.
Narrowly attached to the stem; close or nearly distant; short-gills frequent; grayish to brownish at first, becoming darker brown; sometimes with a mottled appearance; sometimes with pale edges.
6–10 cm long; 1.5–3 mm thick; more or less equal, or tapering slightly toward the base; when fresh and young often finely ridged with longitudinal lines of whitish flocculence, but soon becoming bald; white when young, becoming whitish toward the top and brownish to brown below; fragile; hollowing; basal mycelium white.
Thin; brownish; unchanging when sliced.
Dark brown to purple-brown or nearly black.
Spores 13–18 x 7–10 µm; subamygdaliform; with a large pore (2 µm); verrucose; reddish brown and uniguttulate in KOH; dextrinoid. Basidia 4-sterigmate. Cheilocystidia 25–65 x 7.5–10 µm; cylindric to sublageniform; flexuous; with subclavate to subcapitate apices; smooth; thin-walled; hyaline in KOH. PLeurocystidia not found. Pileipellis cellular/hymeniform; hyaline to brownish in KOH.
Panaeolina foenisecii Look-Alikes
Panaeolus cinctulus or Panaeolus olivaceus
Similar to Panaeolina foenisecii. However, they can be distinguished by their black spores. Correct identification is essential because both Panaeolus cinctulus or Panaeolus olivaceus are psychedelic while Panaeolina foenisecii is arguably not.
Usually larger with veil remnants on edge of cap or stalk.
Yellowish cap, lighter gills.
The Dung Roundhead, has a transient ring and leaves a brown spore print.
The Turf Mottlegill, has a dark-brown cap when wet and dries out to become mid brown.
Panaeolina foenisecii Toxicity
There is evidence that children can become ill after eating these little brown mushrooms, and so on a precautionary basis at least they should be treated as toxic toadstools and not gathered for eating.
Depending on where in the world they are growing, there is research showing that there can be small amounts of psilocybin in some of these fungi, but almost certainly at much too low a concentration for them to be hallucinogenic.
Panaeolina foenisecii Taxonomy and Etymology
This species was described in 1800 by Christiaan Hendrick Persoon, who named it Agaricus panaeolinia. French botanist and mycologist René Charles Joseph Ernest Maire (1878-1949) transferred the Brown Mottlegill to its present genus in 1933.
Panaeolina foenisecii is the type species of the Panaeolina genus, which contains very few species.
There is no consensus about the correct taxonomic position of fungi in the genera Panaeolus and Panaeolina, which some authorities include in the family Strophariaceae and others in the Bolbitiaceae.
Panaeolina, the genus name of this little brown mushroom, suggests that this species has similarities with those in the genus Panaeolus. Panaeolus means variegated - and indeed the caps of many Panaeolus species are zoned, but the generic name is not a reference to the cap coloring but to the mottled or variegated coloring of the gills.
The mottling effect on the gills of Panaeolina foenisecii is due to patches of spores of different parts of the gill surface-reaching maturity at different times. One other obvious difference between fungi in these two genera can be seen provided you have access to a high-powered microscope: you will see that the spores of Panaeolus fungi are smooth while those of Panaeolinus are minutely roughened.
The specific epithet foenisecii simply refers to haymaking.
Panaeolina foenisecii Synonyms
Agaricus foenisecii Pers. (1800)
Prunulus foenisecii (Pers.) Gray (1821)
Psilocybe foenisecii Pers.) Quél. (1821)
Psathyra foenisecii (Pers.) G. Bertrand
Drosophila foenisecii (Pers.) Quél. (1886)
Coprinarius foenisecii (Pers.) J.Schröt. (1889)
Psathyrella foenisecii (Pers.) A.H. Sm.
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