Anamorph: not known.
Teleomorph: Basidiomata agaricoid, with a strong unpleasant smell. Cap 10-20 cm diam. (to 35cm diam. in European material), round, hemispherical when young, but soon becoming convex to shield shaped, ± flat and not umbonate when mature, smooth, silky, shining white to cream or ivory, the margin not striate, the edge covered with prominent ragged fragments of the white veil that hang down below the cap. Gills crowded, broad, cream, free from the stem. Stem 100-150 x 25-50 mm, robust, enlarged at the base, white with a floccose ragged surface which is particularly prominent shortly below the cap where the veil broke away from the stem. Volva saccate, white, membranous and lobed above, turning ochre to pale brown with age, composed of hyphal tissue. Clamp connections absent. Basidiospores 10-12 x 7-8 µm (generally smaller in European collections), Q = 1.4-1.5, broadly ellipsoidal to ± cylindric-ellipsoidal, quite thin-walled, amyloid.
Not formally assessed. Ony known from two sites in southern England. Treated as Vulnerable (D2) in the provisional RDL (Evans et al. 2006). Possibly introduced with Quercus ilex, but long-established.
The only British representative of Amanita subsection Amidellae, with an irregular margin to the cap formed from fragments of the veil and a large saccate volva from which the stem develops.
Found in soil under Quercus ilex, and on calcareous grassland associated with Helianthemum nummularium.
Recorded from VC7 N Wiltshire and VC10 Isle of Wight.