Coker's Amanita Identification Guide

First Impressions and the Woods You Are In

Coker's Amanita is a statement mushroom. In oak and pine woodland of eastern North America, from the Carolinas and the southern Appalachians through the Gulf states and north into the Ohio valley, it emerges from sandy or well-drained soil in late summer and early autumn, usually singly or in small scattered groups. What you see first is a large, hard, chalk-white mushroom standing well clear of the litter, its cap studded with coarse, angular, upright warts that catch the light like a bed of small pyramids. The whole fruit body is heavy and dense compared with most white mushrooms of similar size, and the stalk plunges deep into the ground, so a specimen pulled rather than dug will always be incomplete and often unidentifiable. Bring a knife or a trowel; the base of this species is more diagnostic than the cap.

Reading the Cap

The cap runs 7-15 cm across, occasionally to 20, convex when young and expanding to broadly convex or nearly flat. The ground colour is white to off-white, sometimes ageing to pale cream or with faint tan tints over the disc, and the surface between the ornaments is dry to slightly tacky in wet weather. The ornamentation carries the identification. Universal veil remnants sit on the cap as firm, conical to pyramidal warts, several millimetres tall, arranged in rough concentric zones; they are hard rather than cottony, they can be prised off individually with a fingertip, and toward the margin they flatten and often curve outward and downward. The cap edge is characteristically appendiculate, hung with ragged whitish fragments of the partial veil that dangle for several millimetres. The margin is not striate, which matters when working through the genus.

The Gills

Gills are free or narrowly attached at a line, close to crowded, moderately broad, and white to pale cream, sometimes taking on a faint yellowish or ivory cast with age. With a lens the edges look minutely fringed or fibrillose, a fine woolly line rather than a clean margin. Short gills are truncate. Bruised gills do not change colour appreciably, though damaged tissue in old specimens may discolour dull brownish with decay.

Stipe, Ring and the Rooting Base

The stalk is long and imposing, 10-20 cm and occasionally more, 1.5-3 cm thick, white, and firm to hard. Above the ring it is smooth to finely powdery. Below the ring it is roughened, floccose-scaly or shaggy, and those scales frequently curve upward or outward. The ring itself is high on the stalk, membranous, broad, and characteristically flaring or double-edged, with a soft cottony or floccose underside; it often persists well but can collapse against the stem in rain.

Excavate the base carefully and completely. It swells into a large, firm, spindle-shaped to elongate-clavate bulb that tapers downward into a rooting point, often ten centimetres or more below the litter surface. Around the upper part of that bulb sit several irregular concentric rings or bands of recurved, scaly, wart-like volval remnants, giving the base a shaggy, tiered appearance. There is no free sack-like volva and no clean marginate rim. The combination of a deeply rooting spindle base plus recurved scaly bands is the most reliable single character in the species, and it is the reason careless collecting ruins so many specimens.

Flesh and Colour Change

Slice the mushroom from cap to root. The flesh is white, thick and firm, notably solid in the stalk when young and becoming pithy or partly hollow with age. Colour change is minimal: sound tissue stays white or develops only a faint pallid cream or dull brownish tinge in the base over a long period. There is no rapid reddening, no blueing and no blackening. The odour of fresh material is faint and unremarkable, though older specimens and the cut base can develop a strong, sharp, slightly unpleasant smell that is worth noting as a character of the wider group.

Taking a Spore Print

Cut a mature cap free and rest it gills-down on a half-black, half-white card under a bowl for two to six hours. The print is white to cream and reads clearly against the black half. If you have Melzer reagent, mount a scrape of the deposit: the spores are amyloid, staining grey-blue, which together with the unstriate margin, the firm warts and the rooting bulb places the species in Amanita section Lepidella. Under the microscope the spores are smooth, colourless, ellipsoid to elongate, roughly 11-14 by 7-9 micrometres. Amyloidity is not optional information here; it is the character that separates this whole group from the striate-margined amanitas at a stroke.

Habitat, Partners and Season

This is an ectomycorrhizal fungus, so it always fruits from soil in the presence of partner trees and never on wood, chips or dung. Oaks and pines are the classic associates, frequently together on sandy or gravelly, well-drained ground, and it also turns up in mixed woodland with hickory. Fruiting runs from July through October, with the best flushes several days after a heavy summer storm. Because the base roots so deeply, fruit bodies stand up well to dry spells and can persist in recognisable condition for a week or more, slowly discolouring at the edges.

Separating It from Look-Alikes

The nearest confusions are all within the same section. Amanita ravenelii is a big white eastern species too, but its cap ornaments are lower, granular to pyramid-shaped and often buff to tan, its ring hangs simply rather than flaring, and its base is an abrupt rounded bulb with a girdle of soft powdery volval material rather than a long rooting spindle with recurved scales. Amanita polypyramis has softer, more cottony to floccose cap warts that crumble under a finger, a more fragile ring, and a bulbous but not markedly rooting base. Amanita abrupta is smaller and more slender, with tiny warts, a smooth stalk below the ring and a strikingly abrupt, almost spherical basal bulb that stops flat rather than rooting. Amanita onusta is dingy grey to sordid brown, much smaller, with grey-tipped ornaments and a tapered rooting base. Amanita daucipes has an orange-pink to salmon tinted powdery base shaped like a carrot and a warm-tinted cap. Outside the section, the destroying angels are pure white with smooth, unornamented caps and a loose membranous sack, and the shaggy parasols such as Chlorophyllum rachodes have scaly caps but no volval material at all on the stalk base, a movable double ring, and flesh in the stalk that reddens when cut. If your specimen has a genuine sack around the base, or a smooth cap, or a grooved cap margin, it is not this species.

A Working Sequence

Large white cap with hard concentric pyramidal warts, appendiculate margin, free white gills, flaring floccose ring, shaggy scaly stalk below the ring, long spindle-shaped rooting base with recurved bands of volval scales, white flesh with little change, white amyloid spore print, oak and pine soil in late summer. Dig the whole thing out; the root is half the answer.