The
cap ranges from in diameter. It starts convex, sometimes broadly conical, and has edges (margins) that are curved in against the
gills. As the cap grows and expands, it becomes broadly convex and then flattened, sometimes developing a central elevation, or
umbo, which may project prominently from the cap surface. Based on the collective descriptions of the five taxa now considered to be
G. marginata, the texture of the surface shows significant variation. Smith and Singer give the following descriptions of surface texture: from "viscid" (
G. autumnalis), to "shining and viscid to lubricous when moist" (
G. oregonensis), to "shining, lubricous to subviscid (particles of dirt adhere to surface) or merely moist, with a fatty appearance although not distinctly viscid", to "moist but not viscid" (
G. marginata). The cap surface remains smooth and changes colors with humidity (
hygrophanous), pale to dark
ochraceous tawny over the disc and yellow-ochraceous on the margin (at least when young), but fading to dull tan or darker when dry. When moist, the cap is somewhat transparent so that the outlines of the gills may be seen as striations. The
flesh is pale brownish ochraceous to nearly white, thin and pliant, with an odor and taste varying from very slightly to strongly like flour (
farinaceous). The gills are typically narrow and crowded together, with a broadly
adnate to nearly
decurrent attachment to the stem and convex edges. They are a pallid brown when young, becoming tawny at maturity. Some short gills, called lamellulae, do not extend entirely from the cap edge to the stem, and are intercalated among the longer gills. The
stem ranges from long, 3–9 mm thick at the apex, and stays equal in width throughout or is slightly enlarged downward. Initially solid, it becomes hollow from the bottom up as it matures. The membranous
ring is located on the upper half of the stem near the cap, but may be sloughed off and missing in older specimens. Its color is initially whitish or light brown, but usually appears a darker rusty-brown in mature specimens that have dropped spores on it. Above the level of the ring, the stem surface has a very fine whitish powder and is paler than the cap; below the ring it is brown down to the reddish-brown to
bistre base. The lower portion of the stem has a thin coating of pallid
fibrils which eventually disappear and do not leave any scales. The
spore print is rusty-brown.
Microscopic characteristics The spores measure 8–10 by 5–6
μm, and are slightly
inequilateral in profile view, and egg-shaped in face view. Like all
Galerina species, the spores have a
plage, which has been described as resembling "a slightly wrinkled plastic shrink-wrap covering over the distal end of the spore". The spore surface is warty and full of wrinkles, with a smooth depression where the spore was once attached via the
sterigmatum to the
basidium (the spore-bearing cell). When in
potassium hydroxide (KOH) solution, the spores appear tawny or darker rusty-brown, with an apical callus. The basidia are four-spored (rarely with a very few two-spored ones), roughly cylindrical when producing spores, but with a slightly tapered base, and measure 21–29 by 5–8.4 μm.
Cystidia are cells of the fertile
hymenium that do not produce spores. These sterile cells, which are structurally distinct from the basidia, are further classified according to their position. In
G. marginata, the pleurocystidia (cystidia from the gill sides) are 46–60 by 9–12 μm, thin-walled, and
hyaline in KOH,
fusoid to
ventricose in shape with wavy necks and blunt to
subacute apices (3–6 μm diameter near apex). The cheilocystidia (cystidia on the gill edges) are similar in shape but often smaller than the pleurocystidia, abundant, with no club-shaped or abruptly tapering (
mucronate) cells present.
Clamp connections are present in the
hyphae.
Similar species '' is one of several edible lookalike species.|alt=About two dozen brownish-orange mushrooms clustered together and growing on a piece of wood that is itself covered with green moss. In the center of each of the mushroom caps is a distinct circular region that is a slightly different color (both darker and lighter) that the rest of the cap. The deadly
G. marginata may be mistaken for a few
edible mushroom species such as
Armillaria mellea,
Psilocybe cyanescens and
Kuehneromyces mutabilis.
K. mutabilis (syn.
Pholiota mutabilis) produces fruit bodies roughly similar in appearance and also grows on wood, but may be distinguished by its stems bearing scales up to the level of the ring, and from growing in large clusters. However, the possibility of confusion is such that
K. mutabilis is not recommended for consumption without expert and extremely certain identification. Microscopic examination shows smooth spores in
Pholiota.
K. mutabilis may be distinguished by the presence of scales on the stem below the ring, the larger cap, which may reach a diameter of , and spicy or aromatic odor of the flesh. The related
K. vernalis is a rare species and even more similar in appearance to
G. marginata. Examination of microscopic characteristics is typically required to reliably distinguish between the two, revealing smooth spores with a
germ pore. Another potential edible lookalike is the "velvet shank",
Flammulina velutipes. This species has gills that are white to pale yellow, a white spore print, and spores that are elliptical, smooth, and measure 6.5–9 by 2.5–4 μm. A rough resemblance has also been noted with the edible
Hypholoma capnoides, the 'magic' mushroom
Psilocybe subaeruginosa, as well as
Conocybe filaris, another poisonous amatoxin-containing species. ==Habitat and distribution==