Typically on fallen, decaying leaves of Quercus. Autumn. See The Norwegian Mycological Database.

Pileus up to 5 mm across, hemispherical to parabolical, becoming plano-convex, often with somewhat flattened centre, or sometimes with a small umbo, sulcate, translucent-striate, pruinose, glabrescent, pale pink, pinkish-apricot to brownish-pink, often darker at the centre, with age often paler to whitish pink. Lamellae 5 - 13 reaching the stipe, ascending to subhorizontal, fairly broad, narrowly to broadly adnate, sometimes decurrent with a short tooth, pink to pinkish-white, the edge convex, white. Stipe up to 15 (-40) x 0.3 mm, straight to curved, equal, pruinose, glabrescent except for the base, the base somewhat bulbous, fairly dark grey at the apex in younger stages and grey below, becoming watery grey to watery white, insitituous or sometimes attached with a whorl of very thin, radiating fibrils. Odour none.

Basidia 19-25 x 7-9 µm, clavate, 2-spored and clampless, with sterigmata up to 7 µm long. Spores 10.2-12.1 x 3.8-4.7 µm, elongated pip-shaped to somewhat cylindrical, amyloid. Cheilocystidia 14-29 x 6-16 µm, forming a sterile band, clavate to obpyriform, clampless, covered with fairly numerous, evenly spaced, cylindrical excrescences 1 - 5 µm long. Pleurocystidia absent. Lamellar trama vinescent in Melzer’s reagent. Hyphae of the pileipellis up to 12 µm wide, densely covered with warts, clampless. Hyphae of the cortical layer of the stipe diverticulate, clampless. Caulocystidia clavate to subglobose, diverticulate.

According to Maas Geesteranus (1986a: 178) Mycena smithiana has 2-spored basidia without clamp connections. Similar-looking specimens found on fallen leaves of Betula in mountain birch forest and on fallen leaves of Salix in alpine areas have been associated with this species. They differ in having 4-spored basidia and possibly in other features. These taxa are in great need of further study. Aronsen & Gulden (2007) proposed the new species M. exilis based on material growing on fallen Salix leaves in alpine areas.

M. smithiana is a member of sect. Polyadelphia Singer ex Maas Geest. where it can be identified on account of the pink colour that always is present, the fairly broad lamellae, the narrow spores, and the occurence on fallen, decaying oak leaves. It may occur together with M. mucor (Batsch) Gillet, which can be separated because of a basal disc and M. polyadelpha (Lasch) Kühner, which is entirely white. M. exilis Aronsen & Gulden has a predominantly brown pileus only occasionally with a faint pink tinge, 4-spored basidia, presence of clamps, and smaller but slightly broader spores; further more it grows on Salix leaves. M. riparia Maas Geest., M. juncicola (Fr.) Gillet, and M. tubarioides (Maire) Kühner have a pink pileus too, but those species grow on various monocotyledoneae in wetland areas. M. catalaunica Robich, known from Italy, has broadly pip-shaped to subglobose spores.