Coker's Amanita

Amanita cokeri is one of the most architecturally impressive fungi of the southeastern United States, a large, chalk-white mushroom whose cap bristles with sharply pointed, recurved warts arranged in rough concentric rings. It was named for William Chambers Coker, the North Carolina botanist whose monographs on the amanitas of the southeastern states remain foundational.

The species belongs to the section Lepidella, a group of mostly white, robust amanitas with amyloid spores, floccose or powdery universal veils, and stem bases that are often rooting, spindle-shaped, or decorated with rows of scales rather than ending in a clean membranous sac. Lepidellas tend to be heavy, dense, and slow to decay.

The overall impression is unmistakable in the field: a big white mushroom that looks studded or spiked, standing solitary in oak and pine woods with a deeply buried, scaly root.

Cap

Large, commonly 7-15 cm and sometimes over 20 cm across, convex then broadly flat. The surface is white to cream or faintly buff, dry, and covered with firm, conical to pyramidal warts that curve downwards and outwards, usually arranged in loose concentric zones. The warts are largest at the centre and smaller near the edge. The margin is not grooved and may hang with cottony veil fragments.

Gills

Free to very narrowly attached, crowded, white to cream, sometimes with minutely ragged or floccose edges. Short gills are numerous.

Stipe

8-20 cm long, thick and firm, white, smooth above the ring and shaggy or floccose-scaly below it. The ring is large, membranous, and typically has a cottony, floccose underside. The base enlarges into a stout, rooting, club-shaped or turnip-shaped bulb that is buried deeply and encircled by several rows of recurved scales or hoops of veil tissue.

Flesh and spore print

Flesh white, thick, firm, essentially unchanging when cut, occasionally with faint pale discolouration in age. Odour mild to slightly unpleasant in mature specimens. Spore print white; spores are ellipsoid and amyloid.

Amanita cokeri grows on soil in oak and pine woodland across the southeastern United States, extending north into the mid-Atlantic states and the southern Appalachians, and west into parts of the south-central states. It shows a strong preference for sandy or well-drained acidic soils in mixed oak-pine forest.

Fruiting occurs from mid-summer into autumn, chiefly July through October, following periods of heavy rain. Fruit bodies usually appear singly or in small scattered groups rather than in troops, and the deeply rooting base means much of the mushroom is below ground.

Like other members of the genus, this species is ectomycorrhizal, forming nutrient-exchange sheaths on the fine roots of oaks and pines. Section Lepidella species tend to invest heavily in large, dense fruit bodies, and their deep rooting bases suggest an ability to draw on resources well below the litter layer.

The heavy universal veil that produces the recurved warts is laid down while the fruit body is still an enclosed button. As the cap expands, the veil breaks into the characteristic pyramids, and the material left at the base forms the rows of scales around the bulb. Both veil structures degrade slowly, which is why old specimens can still be recognised weeks after they emerge.

Amanita ravenelii is similar in size and habitat but its cap warts are less sharply recurved and more crumbly, and its bulb carries a distinct basal collar of veil tissue. Amanita polypyramis has softer, more powdery to floccose patches rather than firm pyramids, and a broadly rounded bulb.

Amanita daucipes is separated by the carrot-shaped bulb suffused with pinkish-orange powder, and Amanita onusta is much smaller with greyish, sordid warts. The Destroying Angel, Amanita bisporigera, is also white but has an entirely smooth cap and a thin membranous sac-like volva rather than a scaly rooting bulb.