BRIEF DESCRIPTION: Amanita ristichii is a small, mostly white mushroom; its stem is annulate and has a sheathing, membranous volva at its base; usually its gills are strikingly orange-white or pink; its cap has relatively short marginal striations.

The spores measure (9.2-) 10.2 - 13.9 (-17.0) x (6.6-) 7.0 - 9.0 (-12.8) µm and are ellipsoid to elongate (infrequently broadly ellipsoid) and inamyloid. Clamps are frequent at the bases of basidia.

It is one of the small, North American group within section Vaginatae that have plentiful two-spored basidia, although, within that group, it is isolated by its unpigmented cap, sometimes pinkish gills, short marginal striations on the cap, and the more robust volva at the stipe base.

Amanita ristichii is known only from southeastern Canada and from New Hampshire and Maine (from which it was originally described) in the U.S.A. It fruits in July and August. The species was named for Dr. Samuel S. Ristich.

It is noteworthy that some basidiocarps of the Canadian material are larger than any found in the U.S. It is associated with Canadian Hemlock, White Pine, Aspen, and fir.

For comparisons to similar taxa (all from eastern North America) see A. virginiana (Murrill) Murrill. -- R. E. Tulloss