Bleeding bonnet

Appearance

The cap of ''M. sanguinolenta'' is either convex or conic when young, with its margin pressed against the stem. As it expands, it becomes broadly convex or bell-shaped, ultimately reaching a diameter of 3–15 mm . The surface is initially covered with a dense whitish-grayish coating or powder that is produced by delicate microscopic cells, but these cells soon collapse and disappear, leaving the surface naked and smooth. The surface is moist with an opaque margin that soon developing furrows. The cap color is variable but always some shade of bright or dull reddish-brown with a dull grayish-brown margin. The flesh is thin, not very fragile, sordid reddish, and exudes a reddish latex when cut. The odor and taste are not distinctive.

The gills are adnate or slightly toothed, and well-spaced. They are narrow to moderately broad, sordid reddish to grayish, with even edges that are dark reddish-brown. The stem is 2–6 cm long, 1–1.5 mm thick, equal in width throughout, and fragile. The base of the stem is covered with coarse, stiff white hairs, while the remainder is covered with a drab powder that soon sloughs off to leave the stem polished, and more or less the same color as the cap. It also exudes a bright or dull-red juice when cut or broken. The edibility of the mushroom is unknown—but it is considered too insubstantial to be of culinary interest.

The spores are 8–10 by 4–5 μm, roughly ellipsoid, and only weakly amyloid. The basidia four-spored . The pleurocystidia are rare to scattered or sometimes quite abundant, narrowly to broadly ventricose, measuring 36–54 by 8–13 μm. They are filled with a sordid-reddish substance. The cheilocystidia are similar to the pleurocystidia or shorter and more obese, and very abundant. The flesh if the gill is made of broad hyphae the cells of which are often vesiculose in age, and stain pale reddish-brown in iodine. The flesh of the cap is covered with a thin pellicle, and the hypoderm is moderately well-differentiated. The remainder of the cap flesh is floccose and filamentous, and all except the pellicle stain pale vinaceous-brown in iodine. Lactiferous hyphae are abundant.

Naming

The other "bleeding Mycena" is readily distinguished from ''M. sanguinolenta'' by its larger size, different color, growth on rotting wood, and presence of a sterile band of tissue on the margin of the cap. Further, ''M. sanguinolenta'' consistently has red-edged gills, while the gill edges of ''M. haematopus'' are more variable. The similarly named ''M. subsanguinolenta'' has red to orange juice, is slightly yellower, and does not have pleurocystidia. ''M. plicatus'' has a similar furrowed cap, but also has a tough stem and does not ooze liquid when injured. ''Mycena'' specialist Alexander H. Smith has noted a "striking" resemblance to ''M. debilis'', but this species has different colors , produces uncolored latex, and does not have differently-colored gill edges.

Distribution

''Mycena sanguinolenta'' is common and widely distributed. It has been found from Maine to Washington and south to North Carolina and California in the United States, and from Nova Scotia to British Columbia in Canada. In Jamaica, it has been collected at an elevation of 1,800 m. The distribution includes Europe and Australia. In Asia, it has been collected from the alpine zone of the Changbai Mountains in Jilin Province, China, and from the provinces of Ōmi and Yamashiro in Japan.

Habitat

The fruit bodies grow in groups on leaf mold, moss beds, or needle carpets during the spring and fall. It is common in forests of fir and beech, and prefers to grow in soil of high acidity.