Grooved bonnet

Appearance

The cap of the ''M. polygramma'' fruit body is 2 to 4 cm in diameter, and initially egg- to cone-shaped, but expands to become conic to bell-shaped or nearly convex with an abrupt small umbo, or at times plane with a conic umbo. On young fruit bodies, the cap margin is slightly curved inward, and frequently has scalloped edges; in maturity the margin flares out, or is recurved and wavy. The surface of the cap is initially covered with short, fine whitish or grayish hairs that often persist until near maturity. With age, the cap surface becomes smooth, the color dark brownish-gray to black beneath the bloom, fading slowly to a pale gray, and nearly pinkish-buff at times. The cap margin is opaque and frequently has narrow, deep furrows or grooves, with the surface often more or less uneven and appearing as if streaked with glistening lines. The flesh is very hard and cartilaginous, watery grayish to white, rather thin, and with no distinctive odor and a mild taste.

The gills are narrowly adnate or have a short decurrent tooth, and are packed close together, with 30–38 gills reaching the stem. They are broad anteriorly , white or whitish, in age flushed with pink, often with sordid-brownish stains, and with edges pallid and even. The stem is 6 to 15 cm long, 0.2 to 0.5 cm thick, very brittle and cartilaginous, equal, and tubular. It sometimes has a well-developed pseudorrhiza that resembles white cotton, and the base is covered with stiff white hairs, and often it stains reddish brown. The surface has fine straight or sometimes twisted longitudinal striations. The surface is ashy-gray or paler grayish-brown beneath the silvery covering, at times nearly smooth, with the apex pallid and faintly powdered.
''Mycena polygramma'' is a bioluminescent mushroom, although the extent of luminescence can vary considerably. The mushroom is inedible, and has a mild to slightly acrid taste and a "pleasant" odor.

Naming

Tall and slender forms of ''Mycena polygramma'' somewhat resemble ''M. pullata'' or ''M. praelonga''. The former species is distinguished by its color, and the latter by its relationship to ''M. alcalina'' and its habitat on sphagnum.

Distribution

The fruit bodies of ''M. polygramma'' grow in groups or sub-clusters under hardwoods, particularly deciduous trees such as oak, maple, and basswood. In North America, it has been collected from North Carolina, Massachusetts, New York, and Michigan, where it fruits from June to October. The fruit bodies are susceptible to attack by the parasitic fungi ''Spinellus fusiger'' and ''S. macrocarpus''.

Typically found on twigs or buried wood, the fungus is known to be a vigorous decomposer of lignin and cellulose in leaf litter. ''Mycena polygramma'' is a saprobic fungus, and is one of many fungi that contribute to plant litter decomposition in forest ecosystems through nutrient recycling and humus formation in soil. It is a lignocellulose decomposer of larch litter, and can break down both lignin and carbohydrates, although it has a preference for carbohydrates. In an experiment testing the ability of several litter-decomposing fungi to remove lignin from leaves of the perennial grass ''Miscanthus sinensis'', under pure culture conditions, ''M. polygramma'' showed limited ability to cause the mass loss of lignin.

Rare in North America, the fungus is common in Europe, including Great Britain. They have been collected on the Falkland Islands, and Japan.

Habitat

The fruit bodies of ''M. polygramma'' grow in groups or sub-clusters under hardwoods, particularly deciduous trees such as oak, maple, and basswood. In North America, it has been collected from North Carolina, Massachusetts, New York, and Michigan, where it fruits from June to October. The fruit bodies are susceptible to attack by the parasitic fungi ''Spinellus fusiger'' and ''S. macrocarpus''.

Typically found on twigs or buried wood, the fungus is known to be a vigorous decomposer of lignin and cellulose in leaf litter. ''Mycena polygramma'' is a saprobic fungus, and is one of many fungi that contribute to plant litter decomposition in forest ecosystems through nutrient recycling and humus formation in soil. It is a lignocellulose decomposer of larch litter, and can break down both lignin and carbohydrates, although it has a preference for carbohydrates. In an experiment testing the ability of several litter-decomposing fungi to remove lignin from leaves of the perennial grass ''Miscanthus sinensis'', under pure culture conditions, ''M. polygramma'' showed limited ability to cause the mass loss of lignin.

Rare in North America, the fungus is common in Europe, including Great Britain. They have been collected on the Falkland Islands, and Japan.