Fruiting body a soft, tomentose to finely pubescent mold, white, becoming pinkish to cream-buff, powdery in age, parasitizing stipe and cap tissue of the host; odor and taste not investigated.
Perithecia and ascospores rare, not seen; according to Rogerson and Simms, ascospores (15)18-22 (26) X 2-4 (5) µm, smooth, subfusiform, at maturity, typically one-septate, the ends pointed, not apiculate.
Asexual spores of two types: 1) aleuriospores: globose, spiny, thick-walled, 13.5-17.5 µm broad (including ornamentation), joined to a secondary, thin-walled, more or less hemispheric cell; 2) conidia: cylindrical-ellipsoid, 14.0-25.5 x 4.0-5.0 µm, thin-walled, smooth, contents granular, or with one to several oil droplets, some centrally septate; aleuriospores pinkish-buff in deposit.
Parasitic on Helvella species, especially Helvella lacunosa; fruiting from mid to late winter; common.
Hypomyces cervinigenus is the parasitic mold commonly seen on Helvella lacunosa. Normally greyish-black, the Elfin Saddle is transformed into a whitish to pinkish-buff mummy, the surface powdery from large numbers of asexually produced spores. Interestingly, sexual reproduction in Hypomyces cervinigenus is rare, or at least rarely seen, thus for many years it was known by the name given to the asexual or anamorphic stage, Mycogone cervina.
Another parasite of Helvella lacunosa is Clitocybe sclerotoidea, a basidiomycete that forms clusters of small, greyish mushrooms on the remains of the Elfin Saddle.