Smith's Amanita

Amanita smithiana is a robust white amanita of the conifer forests of the Pacific Northwest, named for Alexander H. Smith, one of the most prolific North American mycologists of the twentieth century. It is a member of section Lepidella, the group of white, heavy-bodied amanitas with amyloid spores and floccose universal veils that leave soft patches on the cap and ragged material on the stem base.

In the field it registers as a chunky white mushroom with an untidy look: soft cottony scales scattered over the cap, shreds of veil hanging from the cap edge, a shaggy stem, and a ring so fragile that it is often reduced to loose fibres by the time the cap opens.

The character that pins it down is the stem base. Rather than the clean membranous cup of the death-cap group or the ringed bulb of the fly agarics, it tapers downwards into a spindle-shaped or narrowly club-shaped rooting base finished with irregular scaly rings or ragged remnants.

Cap

5-15 cm across, convex then broadly flat. The surface is white to cream, sometimes discolouring to pale tan or buff with age, dry, and decorated with soft, cottony to felty patches and irregular warts of universal veil. The margin is often ragged with hanging veil fragments and is not grooved.

Gills

Free to narrowly attached, crowded, white to pale cream, sometimes with faint tan tints in age. Gill edges are minutely floccose. Numerous short gills are present.

Stipe

8-18 cm long, thick, white, and floccose-scaly or shaggy below the ring. The ring itself is soft, cottony, and evanescent, frequently collapsing into a fibrous zone. The base tapers downwards into a spindle-shaped, carrot-shaped, or narrowly club-shaped rooting structure marked by irregular scaly rings or ragged veil remnants; there is no free membranous sac.

Flesh and spore print

Flesh white, thick, and firm, staining slowly pale tan or pinkish-buff in some collections but often unchanging. Odour mild when young, becoming stronger and slightly sharp or bleach-like in maturity. Spore print white; spores ellipsoid and amyloid.

This species is a Pacific Northwest specialty, occurring from British Columbia through Washington and Oregon into northern California, and inland to the mountains of Idaho. It is mycorrhizal with conifers, particularly Douglas-fir, and also occurs with hemlock, pine, and spruce in mature coniferous forest.

Fruiting is an autumn event, usually from September into November, following the return of the rains. Fruit bodies grow singly or in small scattered groups, often half-buried in deep conifer duff, and the rooting base is generally hidden beneath moss and needle litter.

Amanita smithiana is ectomycorrhizal with conifers. Its mycelium colonises fine root tips of Douglas-fir and related hosts, forming a mantle and Hartig net that exchange soil-derived nutrients for photosynthetic carbon. The deep, rooting stem base reflects a fruit body that develops well below the surface of the thick duff layer typical of Pacific Northwest forests.

Its autumn fruiting overlaps with a wide range of other conifer-associated fungi, and it shares habitat with matsutake in many of the same Douglas-fir and hemlock stands. Because Lepidella fruit bodies are dense and slow to break down, individual specimens persist for weeks, gradually discolouring to tan as they age.

Tricholoma murrillianum, the western matsutake, is the classic confusion in the same forests. It differs fundamentally in having gills that are attached and notched at the stem rather than free, a firm fibrillose ring formed from a partial veil only, no universal veil patches on the cap, and a solid stem base that tapers without any scaly rooting collar, plus a strong distinctive spicy aroma.

Amanita silvicola is smaller and softer, with a more powdery to cottony white cap and a rounded rather than tapering base. Amanita magniverrucata has firm pyramidal warts rather than soft cottony patches. White members of the Destroying Angel group, such as Amanita ocreata, have entirely smooth caps and a thin membranous sac-like volva enclosing the base.