Cap 1-3 cm broad, convex, becoming nearly plane in age, the disc sometimes slightly depressed with an uplifted margin; surface translucent-striate when moist, faintly radially furrowed, otherwise smooth, pale grey to buff-grey, fading to ashy-white; flesh extremely thin, colored like the cap, unchanging; odor, mild, taste, mild to faintly raphanoid.
Gills subdecurrent becoming decurrent and distant at maturity, moderately broad, intervenose, concolorous with the cap, unchanging.
Stipe 1.5-4 cm tall, 2-5 mm thick, fragile, hollow, equal to tapering to a slightly narrowed base; surface smooth, moist, white at the apex, pale-grey to dingy light- brown at the base; veil absent.
Spores 9-10 x 3.5-4.5 µm, elliptical to tear-drop shaped, smooth, inamyloid; spore print white.
Scattered, gregarious to in large troops on pine needles, especially Monterey pine (Pinus radiata) and Bishop pine (Pinus muricata); occasional with coast redwood (Sequoia sempervirens); fruiting from mid to late winter.
After periods of rain this fragile, white Marasmius sometimes carpets the ground under pines. The translucent-striate cap (when moist), and widely spaced, decurrent gills are its hallmarks. It is somewhat similar to Marasmiellus candidus but the latter fruits on sticks and branches, its white cap often tinged pinkish in age, while the stipe base is darkly colored.