Amanita squarrosa

The cap of Amanita squarrosa is 30 - 45 mm wide, globose to roughly conical at first, later convex to plane, dry, with an appendiculate and nonsulcate margin.  The cap is at first entirely covered with a whitish to yellowish or pinkish, thin, felted-membranous layer which is soon broken up into patches, scales, or subpyramidal warts.  The cap is whitish to somewhat pinkish and more or less "fibrillose" between the fragments and somewhat has the impression of being silky.  The flesh is up to 5 mm thick over the stem, rather soft, and white.

The gills are free, crowded, whitish, with a concolorous floccose edge, up to 5 mm broad; the short gills are attenuate.

The stem is 75 - 120 × 5 - 10 mm, tapering upward, white, stuffed, and bears a ring, with a clavate to spindle-shaped bulb. The bulb is up to 20 mm wide, more or less pointed at the base.  Below the ring is decorated with densely placed ragged recurved scales and becoming also like a pinecone at the base of the stem and the top of the bulb.  The scales often appear to be arranged in circles around the stem.  The ring is located at the top of the stem and is fibrillose to floccose-powdery and quickly disappears.

The spores measure 8 - 10 × 7 - 9 µm and are subglobose to broadly ellipsoid, occasionally ellipsoid and amyloid.  Clamps are present at base of basidia.

This species was originally described from Japan in Pine-Oak forests.  In the original publication, the authors remark on the species' similarity to Amanita smithiana Bas, which would suggest placement in Bas' stirps Rhopalopus, but expressed concern about the fact that the known species in that group have considerably larger fruiting bodies, smooth stems, and longer proportionately more narrow spores.  They do not mention another characteristic of stirps Rhopalopus, namely, that its species tend to have radicating or very deeply radicating bulbs, a characteristic lacking in A. squarrosa.  Bas suggests that when material does not seem to fit in stirps Rhopalopus, that the reader of his thesis should see stirps Grossa.  Stirps Grossa includes some taxa with subglobose to ellipsoid spores, has no known taxa that are very deeply radicating, and includes fruiting bodies with a considerable variety in size.  However, the extremely scaly stem base of Amanita squarrosa is not to be found in this stirps either.  For the moment, especially without examining dried material, we cannot confidently do more than place this species in Amanita subsection Solitaria.—R. E. Tulloss and L. Possiel

If the bases of the warts are dominated by filamentous hyphae, then the choice in Bas' key is between stirps Ravenelii and strips Solitaria.

If the bases of the warts are dominated by inflated cells, then the choices are stirps Microlepis and stirps Rhopalopus.

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