BRIEF DESCRIPTION: Amanita onusta usually produces a rather small cap with a radicating stipe, but its cap may be more than 100 mm wide on occasion.  It is often densely covered by brownish gray volval warts.

The gills of this species soon become yellowish and appear waterlogged.

Its stipe (rarely up to 150 x 15 mm including the basal bulb) is whitish and often decorated with brownish gray pulverulence.  The partial veil is friable and soon lost.  The bulb at the stipe base is radicating and sometimes strongly sinuous.  Brownish gray volval warts are often densely placed at the top of the stipe's basal bulb.  Sometimes, recurved scales with powdery universal veil on their tips replace the warts on the bulb in whole or in part.

The spores measure (7.0-) 8.0 - 11.0 (-13.0) x (5.0-) 5.5 - 7.0 (-8.3) µm and are broadly ellipsoid to ellipsoid to elongate (rarely subglobose or cylindric) and amyloid.  Clamps are present at bases of basidia.

This species is often associated with oak or pine.

It is a member of Bas' stirps Microlepis.  Perhaps the most similar species is A. costaricensis Tulloss, Halling, G. M. Muell. & Singer nom. prov. of Costa Rica.  Another similar species is A. atkinsoniana Coker.  The latter has warts developing a distinct brownish to chestnut tint.  On the cap of A. atkinsoniana, the warts are significantly shorter (use 10x lens) than those of A. onusta (Bas, 1969) and farther apart.  On the bulb of A. atkinsoniana, the warts appear in many parallel rows and don't usually produce the pronounced production of recurved scales seen in A. onusta.

Amanita onusta is a species of eastern North America; its range extends from Quebec to Mississippi.  The species can be weedy locally, at least in the northeastern U.S. -- R. E. Tulloss