Summa Veg. Scand. II: 346. 1849.
Common Names: false morel, rain mushroom, beefsteak morel
Synonym: Helvella esculenta Fries
Cap 5-9 cm tall, 5-11 cm broad, semi-globose, brain-like, inconspicuously lobed; fertile surface convoluted to wrinkled, lobes separated by deep furrows; color: tan-brown, ochraceous-brown, deep reddish-brown; sterile undersurface of cap cream to buff-colored; margin attached to stipe at several points; context thin, brittle; odor and taste not distinctive.
Stipe 3-6 cm long, 1-3 cm thick, hollow, round to compressed, sometimes grooved or with basal folds; surface smooth to furfuraceous, whitish, often tinged vinaceous-tan.
Spores 18-23 x 9-12 µm, ellipsoid, smooth, with two oil droplets; spores pale yellowish-buff in deposit.
Solitary, scattered to gregarious under conifers, occasionally under hardwoods; common in the Sierra, rare in coastal forests; fruiting from late winter to spring.
Potentially deadly, especially raw, but see comments.
Commonly known as the Brain Mushroom because of its much wrinkled, typically reddish-brown cap, Gyromitra esculenta is one of the more distinctive members of the "False Morel" group. Nonetheless, it is sometimes confused with morels (Morchella spp.) The latter are easily distinguished by their longitudinally ridged, pitted caps. Although the species name suggests edibility, Gyromitra esculenta is a questionable choice for the table as it contains monomethylhydrazine (MMH), a volatile toxin which in high doses can be fatal. Anecdotal evidence and preliminary tests by Duffy and Vergeer suggest that California material may not contain high levels of MMH, but caution is still advised. Although we cannot recommend eating this mushroom, it is commonly consumned in the Western United states. If you do try Gyromitra esculenta, it should always be cooked in a well ventilated area to avoid breathing any monomethylhydrazine that might be present and the cooking liquid should be discarded.
Other California Gyromitras include: Gyromitra infula, Gyromitra montana, and Gyromitra californica. Gyromitra infula has a distinctive saddle-shaped cap, the surface of which is wavy to bumpy, but not wrinkled. Gyromitra montana (Snow Mushroom), until recently known locally as G. gigas, is largely a Sierran species. It is shorter, stockier than G. esculenta with a coarsely wrinkled cap only slightly broader than the stipe. Least likely to be encountered is another Sierran species, Gyromitra californica. A beautiful fungus, it has a broad, brown to olive-brown, wavy cap, the margin of which is usually free, and a fluted, cream-yellow, often tinged pinkish stipe.
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Duffy, T.J. (2008). Toxic Fungi of Western North America. MykoWeb.
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