California Mycena

The cap is initially conic or bell-shaped, but flattens out in maturity, and typically reaches dimensions of up to 2 cm (3⁄4 in). The cap margins (edges) are curved inwards when young, but as they age they become wavy or crenate (with rounded scallops), develop striations (radial grooves) and may even split. The surface of the cap is dull and smooth. Its color ranges from reddish brown to brownish orange in young specimens, with the color fading as the mushroom matures; the center of the cap is usually darker than the margins. The flesh is thin, and either the same color as the cap or lighter; it may stain a dark red color when bruised. The gills have an adnate attachment to the stem—broadly attached slightly above the bottom of the gill, with most of the gill fused to the stem. They are not closely spaced together, and there are about 15–20 of them. Some of the gills do not extend the full distance from the edge of the cap to the stem. These short gills, called lamellulae, form one to two groups of roughly equal length. All of the gills have a white to pinkish-buff color, with the gill edges ranging from reddish orange to reddish brown to brownish orange. The hollow stem is 3–13 cm (1+1⁄4–5 in) long and 1–3 mm (1⁄16–1⁄8 in) thick, and roughly the same thickness throughout. …

The fruit bodies grow in clusters or scattered on the decomposing leaves and acorns of oak trees, such as Coast Live Oak, Valley Oak and Black Oak. It is common in the coastal oak woodlands of California, where it appears from late autumn to early winter.