Amanita brunnescens

Brown star-footed amanita
Scientific classification
Domain:	Eukaryota
Kingdom:	Fungi
Division:	Basidiomycota
Class:	Agaricomycetes
Order:	Agaricales
Family:	Amanitaceae
Genus:	Amanita
Species:	A. brunnescens
Binomial name
Amanita brunnescens G.F.Atk. (1918)

Amanita brunnescens Mycological characteristics
	Gills on hymenium
	Cap is convex
	Hymenium is free
	Stipe has a ring and volva
	Spore print is white
	Ecology is mycorrhizal
	Edibility is unknown

Amanita brunnescens, also known as the brown American star-footed amanita^[1][2] or cleft-footed amanita is a native North American mushroom of the large genus Amanita. It differs from A. phalloides (the death cap) by its fragile volva and tendency to bruise brown.

Originally presumed to be the highly toxic Amanita phalloides (the death cap) by renowned American mycologist Charles Horton Peck, it was described and named by George F. Atkinson of Cornell University. He named it after the fact that it bruised brown.^[3]

Amanita brunnescens has a mostly brown cap, with possible tones of olive, grey, or red. At maturity the cap is often around 8–9 centimetres (3+1⁄4–3+1⁄2 inches) wide. The cap margins lack universal veil remnants. The shape of the cap can be bell-shaped to convex, becoming planar as it matures. The flesh within the cap is mostly white or cream and can bruise brown. The characteristic Amanita gills are free from the stipe and white. The stipe is also white, with a smooth basal bulb that distinctly splits into a "cleft-foot". It stains reddish-brown on the lower half, especially when handled, and averages about 9 cm tall. A partial veil is present, often white with possible brown coloration. There is no volva, but there may be volval remnants if the fruiting body is excavated carefully, that are white to brownish.^[1]

The odor, if present, is of raw potatoes. a piece of the stipe may need to be cut in order to detect the faint scent.^[1]

The spore print is white, and "the spores measure (7.0-) 8.0–9.2 (-9.5) × (6.5-) 7.2–8.5 (-9.2) μm and are globose to subglobose (occasionally broadly ellipsoid) and amyloid. Clamps are absent from bases of basidia."^[1]

Amanita brunnescens var. pallida is almost identical to the description above, but with a white cap color.^[1]

A. brunnescens' most distinguishing features are the characteristic Amanita stature with warts and partial veil, as well as the cleft foot and reddening base.

Successful mushroom identification relies on the collection of mature, healthy and undamaged specimens. Amanitas can be separated from other agarics by their (usually) tall and slender stature, presence of universal veil remnants and/or a volva, and sometimes a partial veil. Other genera with volvas include Volvariella and Volvopluteus which will never have a partial veil or universal veil remnants on the cap. Those genera also have pink spore prints instead of Amanita's white.^[4][5]

Section Validae, to which A. brunnescens belongs, can be distinguished from other Amanita sections via the smooth bulbous base without a volva, stipe with a partial veil, and no veil remnants hanging off of cap margin. Other Amanita sections have either a conspicuous volva or a concentric/scaly stipe base.^[6]

Amanita amerirubescens has an indistinct (sometimes a little swollen) stipe base, a brassy yellow to reddish cap, and when young, yellowish warts on cap. This species also reddens.^[7]

Amanita flavorubens is similar to A. amerirubescens, but has a yellower cap and warts that retain their yellow color for longer.^[8]

Amanita asteropus is the European version of A. brunnescens.^[9]

It is of unknown edibility and may be poisonous.^[10]

• List of Amanita species