A very large, stocky, ectomycorrhizal mushroom of spruce and other conifer forests, with a brown cap, decurrent whitish gills and a tapering, deeply rooted stem bearing a double ring. It has a mealy or cucumber-like odor and amyloid spores. Its presence in North America is uncertain: sequenced North American collections labeled C. imperiale have turned out to be other Catathelasma species.
Edible and collected for food in Europe and Asia (for example Ukraine, Russia, China and Bhutan), though it can be very tough. Large pale mushrooms with rings include deadly Amanita species, which have free gills and a sac-like volva or bulb at the stem base. Catathelasma has strongly decurrent gills, a double ring and a tapering, rooting stem without a volva. North American material called 'imperiale' may be a different species, and its edibility has not been confirmed separately.
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Habitat
Ectomycorrhizal with conifers, especially spruce; in the Carpathians in coniferous and spruce forests at about 400-1,000 m.
Distribution
Europe, from Scandinavia across northern continental Europe south to Italy; Asia (China, Korea, Japan). North American records are uncertain. DNA from North American specimens identified as C. imperiale has so far matched C. evanescens or C. ventricosum (Wikipedia). MushroomExpert treats C. imperiale as a western species, and notes that western concepts of C. ventricosum with browner caps and mealy odors invite confusion with it.
Characteristics
Cap: 8-40 cm across, convex and sticky when young, later flat or slightly sunken and dry, orange-brown to hazel-brown with darker patches. Gills: decurrent, crowded, whitish to cream, sometimes forked. Stem: 5-18 cm, tapering downward, often rooting and partly buried, pale brown, with a double ring. Flesh: firm, can be very tough. Odor: mealy or cucumber-like. Spore print: white. Microscopic: spores subcylindrical to fusoid, smooth, amyloid, 12.5-16 x 5-6.5 µm.
