BRIEF DESCRIPTION: The cap of A. constricta is 50 - 130 mm wide, convex when young, becoming plano-convex to plane, eventually subumbonate to umbonate in age, with a strongly sulcate to tuberculate striate margin (20 - 25% of the radius).  The cap is brown to brownish gray, the disc at times is as dark as Chaetura black, often with inconspicuous dark radial streaks.  The flesh is white, sometimes becoming faintly pinkish with exposure (see discussion below).  The volva is absent or present as a membranous fibrillose patch over the cap's center; it is white to buff to (eventually) smoke gray.  Although I have never seen it, the volva is said to bruise salmon color when moistened (see discussion below).

The gills are close to crowded, adnate to decurrent by a short hook when young, becoming free, white at first, becoming gray, and drying tan to sordid tan to brownish gray.  The gills are moderately broad with the edge usually gray and fibrillose.  The short gills are in several ranks.

The stem is 100 - 160 (-200) mm long, 7- 17 mm wide at the apex, white, cylindric or narrowing upward, and exannulate.  The flesh is white, stuffed, becoming hollow.  The membranous volva soon begins to turn gray and become structurally weaker; although I have never observed this, it is said to bruise reddish or salmon when wet then fade back to its previous coloration (see discussion below).

The spores measure (7.2-) 9.5 - 12.8 (-19.0) x (6.2-) 8.2 - 11.5 (-17.8) µm and are inamyloid and globose to subglobose to broadly ellipsoid (occasionally ellipsoid).  Clamps are rather infrequent to rather common at bases of basidia.

Associated with Pacific coastal species of oak and arbutus as well as Douglas Fir. Described originally from California, this species range probably extends into southwestern Canada.

The original description was based on collections of several different species including A. protecta Tulloss & G. Wright and undescribed taxa.  Since there is distinct rusty or ochraceous staining in all parts of A. protecta, this could be the source of the claim that the volva of A. constricta stains.  The protologue's statement that the cap of the present species can be gray may also result from inclusion of A. protecta in the original concept of A. constricta.

At present, no taxa are known to me that appear particularly closely related to A. constricta. The reader may wish to compare the taxa similar to A. submembranacea (Bon) Gröger. -- R. E. Tulloss