frosty bonnet

The cap is white and small, with a diameter typically ranging from 2.5 to 7.5 mm (0.1 to 0.3 in). Initially convex to cucullate (hood-shaped), it flattens during maturity, developing visible surface grooves that correspond to the gills underneath the cap; the surface may also be covered with glistening particles, remnants of the partial veil. The cap is pallid gray with a whitish margin when young, but soon becomes white overall. The flesh is membranous, fragile, and thin (less than 0.5 mm). The gills are free from attachment or narrowly attached (adnexed) to the stem. They are up to 0.5 mm broad, distantly-spaced (usually numbering between 7 and 12), and sometimes adhering to each other to form a slight collar (a pseudocollarium) around the stem. They are translucent-white throughout their development, with a fringed, white edge. The hollow stem is 0.5 to 2 cm (0.2 to 0.8 in) long, and usually curved and threadlike. The bottom of the stem is enlarged into a slight bulb, which is initially nearly spherical. At the very base of the stem is a small, white, and hairy disk-like base that attaches to the substrate. …

Fruit bodies of Mycena adscendens are found scattered to grouped together in twos or threes on fallen twigs, bark, and woody debris of hardwoods during the spring and autumn; it fruits less frequently on the wood of conifers. Fruitings are most common after periods of wet weather. They are also found growing on hazel nuts that have fallen to the ground; two other Mycenas known to grow on this substrate include M. discopus and M. nucicola. In the United States, it is known from Washington to California. It is also found in Europe, and has been collected in Amasya Province, Turkey. The variety carpophila, originally described from Denmark, was reported from Japan in 2003.