What You Should Know
Gyromitra gigas is a massive mushroom and a member of the Ascomycota found in Europe. It is referred to as one of the false morels, due to its similar appearance and occurrence in the spring and early summer in similar habitats to true morels.
This fungus found in many field guides is recognized among species of Gyromitra by its massive stem and its squarish, tightly adherent cap. Some mycologists split Gyromitra gigas into two species, Gyromitra korfii and Gyromitra montana. Gyromitra korfii has a stout, massive stem, and a tan to golden brown or brown cap. It is extremely difficult to distinguish from Gyromitra montana based on field characteristics - although the two mushrooms do grow in different places.
Gyromitra gigas contains small quantities of hydrazines, its content in gyromitrin was scientifically assessed by Viernstein et al. and resulted in about 1mg per kg of fresh mushroom (roughly 1500 fold less compared to esculenta). No casualties have been ascribed to its consumption, parboiling is still highly recommended.
Some guides have listed it as being edible if properly prepared. However, consumption is not recommended due to variability and similarity to other more toxic species of Gyromitra.
Other names: Snow Morel, Snow False Morel, Calf Brain, Bull Nose.
Gyromitra gigas Mushroom Identification
Officially saprobic, but potentially also mycorrhizal--or, like the true morels, donning both ecological hats in the course of its life cycle; found under hardwoods in spring; east of the Rocky Mountains.
3-10 cm high; 4-10 cm across; variable in shape but often blocky and squarish; sometimes vaguely lobed; tightly affixed; broadly wrinkled; convoluted; tan to brown, rarely cinnamon or tawny; undersurface whitish to pale brownish, ingrown with stem where contact occurs.
Whitish; brittle; chambered.
3-8 cm high; 2-6 cm wide; pale tan to whitish; bald; developing broad ribs or waves.
Spores 25-37 x 10-13 µ; broadly fusiform, with a wide, knoblike apiculus (1-3.5 µ high and 3 µ wide) developing at each end with maturity; with one large oil droplet and numerous smaller droplets. Asci 8-spored. Paraphyses clavate to cylindric; with golden to brownish, orangish, or reddish contents.
Gyromitra gigas Taxonomy
Officially, Gyromitra gigas is the correct current name for this species, since Abbott & Currah (1997) synonymized Gyromitra korfii and Gyromitra montana with Gyromitra gigas, and a more recent treatment does not exist. Abbott & Currah examined the spores of a gazillion putative Gyromitra montana specimens from the northern Rocky Mountains, together with spores of a North Carolina type collection of Gyromitra korfii and spores of three Scandinavian collections labeled Gyromitra gigas. The authors found that sporal "features overlap," and that "these taxa should be accepted as conspecific with a rather broad range of ascospore morphology".
Since Gyromitra gigas is the oldest species name among the three, it wins, according to the rules that govern botanical names. A DNA study of this species group has not been published.
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