Clitocybe sclerotoidea

Pileus
Cap 1.0-3.0 (4.0) cm broad, convex, expanding to nearly plane, with or without a low umbo; margin when young sometimes sulcate-striate or wavy, tomentose, incurved, in age decurved to plane, occasionally raised; surface dry, dull, glabrous or with appressed fibrils, the latter unevenly tan-brown over a cream to pale-grey ground color; context white, firm, up to 4.0 mm thick, unchanging when cut; odor not distinctive; taste mild.

Lamellae
Gills adnate, broadly notched to subdecurrent, close, becoming subdistant at maturity, relatively broad, cream-buff to dull tan; lamellulae up to 2-seried.

Stipe
Stipe 1.0-4.0 (6.0) cm tall, 4.0-8.0 mm thick, equal to clavate, solid, cream-colored; surface of apex fufuraceous, lower portion loosely covered with fibrils, sometimes inconspicuously pubescent, the base typically fused with other sporocarps, arising from a dirt-encrusted sclerotium; partial veil absent.

Spores
Spores 7.5 x 10.0 x 3.0-3.5 µm, ellipsoid to subfusoid (spindle-shaped), smooth, thin-walled, hilar appendage not conspicuous, inamyloid; spores creamy-yellow in deposit.

Habitat
In cespitose clusters, rarely solitary, growing from the rotted remains of Helvella lacunosa; fruiting from mid to late winter.

Edibility
Unknown, insignificant.

Comments
An unusual fruiting habit, on the decayed remains of Helvella lacunosa, helps distinguish this small drab mushroom. The typically clustered fruitings grow from a sclerotium, a mass of partially differentiated tissue which includes stipe remnants of a Helvella lacunosa. These are best seen by sectioning a sclerotium. Members of the Collybia racemosa, C. tuberosa group also fruit on decayed mushrooms, but are smaller, less robust, fruit from a grain-sized sclerotium, and do not occur with Helvella lacunosa. Collybia racemosa is particularly distinctive in having a stipe with slender side branches. Also compare with Inocybe geophylla, a similar-sized, whitish mushroom sometimes found under Monterey pine (Pinus radiata) with Helvella lacunosa. The latter is separable by a spermatic odor, a dull-brown spore print, and a sparse fibrillose veil.