The largest eastern North American false morel, with a rounded, tightly wrinkled, brain-like reddish-brown cap on a massive white, ribbed stem. Sliced specimens show many internal chambers. Specimens reported in newspapers as 'monster morels' are usually this species. It fruits in early spring under hardwoods, often in river bottoms.
Edibility disputed; not recommended. It is eaten regionally in the South and Midwest, and gyromitrin was not detected in the one specimen tested by Dirks et al. (2023, Mycologia 115(1)), but a negative test does not prove safety. The serious risk is confusion with the DEADLY Gyromitra esculenta, which contains gyromitrin (converted to monomethylhydrazine) and can be fatal; it is usually smaller, more loosely lobed, grows mostly under conifers and has shorter spores.
Never eat a wild mushroom based on a web page — confirm with an expert.
Habitat
On the ground under hardwoods, especially oaks, in rich humus, often near rotting stumps and downed trees and along river bottoms. Early spring, from March in the South and April to May farther north. Officially saprobic, possibly also mycorrhizal (MushroomExpert).
Distribution
Eastern North America, from Kansas and Oklahoma to the Atlantic coast, especially common in the South and the Mississippi and Ohio River watersheds; its northern limit appears to be the southern Great Lakes. Older European reports are attributed to confusion with other species (Wikipedia; ascomycete.org).
Characteristics
Cap: 5-11 cm high and 6-12 cm wide (MushroomExpert), sometimes much larger; roughly round, never lobed, tightly attached to the stem, tightly wrinkled and brain-like, reddish brown, darkening with age; underside whitish to grayish and mostly hidden. Flesh: whitish to grayish, brittle, heavily chambered, the chambers near the cap surface resembling cauliflower. Stem: 4-10 cm long and 2-10 cm wide, white, felty, becoming ribbed with vertical ribs up to 1 cm across, sometimes graying when handled. Spores: 22-35 x 10-16 µm, ellipsoid, with one large and several smaller oil droplets, smooth or becoming ridged (MushroomExpert).
