Parasola leiocephala

Pileus
Cap 1.5-3.5 cm broad at maturity, at first narrowly ovoid to ellipsoid, expanding to convex, finally nearly plane, the disc sometimes slightly depressed; margin incurved, then decurved, eventually level; surface striate-sulcate to near the disc, the latter, tawny-brown, occasionally tinged rust-brown, elsewhere the ribs pale greyish-buff; context membranous, fragile; odor and taste not distinctive

Lamellae
Gills free, close to subdistant in age, narrow, pallid, eventually grey to blackish, not deliquescing.

Stipe
Stipe 2.5-6.5 cm long, 1-2 mm thick, round, fragile, more or less equal except for a sub-bulbous base; surface pallid, translucent, glabrous; partial veil absent.

Spores
Spores 8.0-11.0 x 7.0-9.5 x 5.0-7.5 µm, heart to apple-shaped to weakly angular in face-view, elliptical with an eccentric germ pore in profile; hilar appendage conspicuous; spores smooth, thin-walled, blackish in deposit.

Habitat
Solitary, scattered, to gregarious in grassy areas, especially under trees, disturbed ground, and decaying wood chips; fruiting spring, summer, and fall, after periods of moisture.

Edibility
Inconsequential.

Comments
Formerly placed in Coprinus, this delicate, ephemeral Parasola is recognized by its translucent, sulcate, pale-grey cap with a yellowish to tawny-brown disc, and free, non-deliquescent gills. Characteristic of the genus is the lack of universal veil fragments on the cap and pileocystidia (setules), features which sets it apart from other small "coprinoid" fungi, e.g. Coprinellus micaceus, Coprinellus disseminatus, and Coprinopsis friesii. Parasola leiocephala is closely related to Parasola plicatilis (= Coprinus plicatilis). The two species in fact cannot be told apart reliably without examining the spores, those of Parasola plicatilis being distinctly larger. Macroscopically, Parasola plicatilis is said to be slightly smaller, more greyish, and appears more restricted to grassy habitats compared to the ecologically variable Parasola leiocephala. Parasola leiocephala is the dominant species in the San Francisco Bay area, but it is possible that the reverse is true elsewhere. Parasola plicatilis has been reported from southern California, but its exact distribution in California is unknown. Parasola leiocephala should also be compared with Parasola auricoma. The latter is larger, more tawny-brown overall, has filamentous cap setae (visible with a strong hand lens), and narrowly attached or barely free gills.