Leucoagaricus americanus

Leucoagaricus americanus

The American parasol or Reddening Lepiota (Leucoagaricus americanus (Peck) Vellinga, 2000) is a mushroom belonging to the Agaricaceae family.

Systematics –
Domain Eukaryota,
Kingdom Fungi,
Division Basidiomycota,
Class Agaricomycetes,
Order Agaricales,
Family Agaricaceae,
Genus Leucoagaricus,
Species L. americanus.
The following is a basionym:
– Agaricus americanus Peck.
The following are synonymous:
– Agaricus americanus Peck;
– Agaricus bresadolae Schulzer;
– Agaricus cupreus Schulzer;
– Chamaeceras bresadolae (Schulzer) Kuntze;
– Fungus bresadolae (Schulzer) Kuntze;
– Lepiota americana (Peck) Sacc.;
– Lepiota bresadolae (Schulzer) Sacc., 1885;
– Lepiota bresadolae Schulzer;
– Lepiota bresadolae var. biornata;
– Leucoagaricus bresadolae (Schulzer) Bon & Boiffard;
– Leucoagaricus bresadolae var. cookeianus Bon;
– Leucocoprinus americanus (Peck) Redhead;
– Leucocoprinus bresadolae (Schulzer) Bon;
– Leucocoprinus bresadolae (Schulzer) M.M.Moser;
– Leucocoprinus bresadolae (Schulzer) Wasser;
– Pseudofarinaceus bresadolae (Schulzer) Kuntze.

Etymology –
The term Leucoagaricus comes from “Leuco-,” which in Greek means “white,” indicating the typical color of many mushrooms in this genus, and “Agaricus,” the genus to which the mushroom belongs, which in turn derives from a Greek term referring to mushrooms in general.
The epithet americanus refers to its native habitat in North America.

Geographic Distribution and Habitat –
Leucoagaricus americanus is widely distributed in North America, primarily east of the Rocky Mountains. It is a saprophyte and grows on sawdust, wood chips, stumps, and soil.
It grows in small, mostly tufted groups from late summer to autumn, in moist, lignin-rich areas, on sawdust, and on dry leaf litter, in parks and gardens. It does not dislike dry climates, in which case it displays its reddish hues early.

Identification –
Leucoagaricus americanus is a mushroom with a cap ranging in size from 3 to 15 cm, initially oval in shape, then convex to flat, umbonate, with a smooth, velvety white cuticle. Upon fracture, it becomes covered with dense concentric scales, starting from the cream-colored margin and turning reddish-brown when fully mature, turning red when handled.
The hymenium consists of dense, free-standing gills with serrated edges. They are white when young, creamy-pink when mature, and first become yellow and then reddish-brown when touched and squeezed.
The stipe is up to 15 cm long and 1-2 cm thick, fusiform to club-shaped, initially full then hollow, initially yellowing, then reddening when rubbed.
The annulus is membranous, located at the top of the stipe, sometimes evanescent when ripe. It is white, and can also turn reddish when mature.
The flesh is white and thick, turning yellowish and then reddish-brown when touched and cut. It has a mushroomy odor and a pleasant flavor.
Regarding chemical reactions, the cap turns orange-brown, then emerald green with Tincture of guaiacum; immediately emerald green with ammonia.
Under the microscope, we see spores measuring 8-11 × 6-7.5 μm, smooth, elliptical, ovoid, thick-walled, with a small, narrow germinal pore, a pronounced apicle, granular, guttulate, dextrinoid, and metachromatic. The basidia are clavate, tetrasporic, some bisporic, without clamp joints, and measure 29-38 × 7.5-9.5 μm. Cheilocystidia are mostly clavate, but also lageniform with a moniliform apex. Pleurocystidia are absent. The pileipellis consists of irregularly intertwined hyphae with clavate or fusiform terminals.

Cultivation –
Leucoagaricus americanus is an uncultivated mushroom.

Uses and Traditions –
Leucoagaricus americanus was first described by Charles Horton Peck, an American mycologist of the 19th and early 20th centuries, in 1869.
Peck’s description lists both the collection habitat, a grassy bank, and the location, Buffalo. It is somewhat similar to Luecoagaricus badhamii (Berkeley & Broome) Singer, which, however, immediately turns bright red at the slightest touch and then turns brown within 1 or 2 minutes; Microscopy is also different; the latter has claviform and ventricose cystidia, with an appendage and containing a red pigment. To differentiate it from related genera (Cystolepiota, Macrolepiota, Leucocoprinus), it is important to observe not only its growth habit, but also its morphology and spore metachromacy, the pileipellis, and the shape of the basidia.
Regarding edibility, it is considered inedible, slightly toxic when raw, and can cause gastric disturbances in some people. However, some texts list it as edible, but it is not recommended for consumption due to possible confusion with toxic species such as Chlorophyllum molybdites.
For this reason, it is an uninteresting mushroom, and the common names used to identify it locally are quite rare. In Italy, it is known very generically as “culumbina”; in France, “lépiote fasciculée”; In English, it is called “American parasol” or “Reddening Lepiota”; there are no common names in the rest of Europe.

Preparation Instructions –
Leucoagaricus americanus is among the mushrooms not considered edible and, in any case, should not be picked for safety’s sake.

Guido Bissanti

Sources
– Wikipedia, the free encyclopedia.
– GBIF, the Global Biodiversity Information Facility.
– Cetto B., 2008. I funghi dal vero, Saturnia, Trento.
– Pignatti S., 1982. Flora d’Italia, Edagricole, Bologna.
– Conti F., Abbate G., Alessandrini A., Blasi C. (eds.), 2005. An annotated checklist of the Italian vascular flora, Palombi Editore.

Photo Source:
– https://inaturalist-open-data.s3.amazonaws.com/photos/412731352/original.jpeg

Warning: The pharmaceutical applications and dietary uses are provided for informational purposes only and do not in any way constitute medical prescriptions. We therefore decline any responsibility for their use for curative, aesthetic, or nutritional purposes.