Marasmius funalis produces
fruit bodies in the form of
mushrooms. Each mushroom has a convex (sometimes completely
hemispherical)
cap of between in diameter. Unlike the caps of other mushrooms, it does not change shape to a flatter convex with age. The cap is fairly smooth, but can have small, parallel furrows towards the edge, The colour differs slightly, depending on the age of the mushroom. While younger specimens sport reddish-brown caps, they are a paler brown in older mushrooms. The cap's surface is dry and dull, and free from hair. The threadlike
stem attaches centrally to the cap, measures from long by thick. It is cylindrical, but may taper slightly, and is covered in short, white hairs. The base of the stem enters the
substrate, and there are no
rhizomorphs visible. The majority of the stem is blackish-brown, but it is a lighter brown at the very top. The white
gills can be adnate or adnexed; that is, they can be attached to the stem by their whole depth, or only part of it. The individual gills are distantly spaced, with between 8 and 12 reaching the stem. Each gill is up to thick, and the edges are even. There are sometimes lamellulae (short gills that do not reach the cap). There is a thin layer, up to thick, of whitish flesh in the cap. It is tough, but it can be bent without breaking. The flesh has no smell or taste. The caulocystidia (cystidia in the stem) measure 60 to 200 by 4 to 7 μm. They are cylindrical and erect, forming the visible bristles. The tip is either pointed or rounded, and the cell walls are smooth and colourless, up to 2 μm thick. They are dextrinoid, meaning they stain a reddish-brown when they come into contact with iodine from Melzer's reagent or Lugol's solution. The
pileipellis, the top layer of
hyphae in the cap, is a
cutis. The cutis is made up of cylindrical hyphae between 2 and 5 μm thick. The inamyloid and thin-walled hyphae are covered in brown
granules. The flesh in the cap is made up of cylindrical hyphae from 4 to 7 μm wide with thin cell walls. They are all
generative hyphae, and run parallel to one another. They can be either inamyloid or only weakly dextrinoid. The flesh in the gills is basically the same as the flesh in the cap, but for the fact that it is completely inamyloid. The hyphae of the
stipitipellis, the uppermost layer in the stem, also form a cutis. The cylindrical hyphae making up the cutis run parallel to one another, and measure from 2.5 to 4.5 μm in width, with walls up to 1 μm thick. They are encrusted with a brown pigment, and are dextrinoid. The flesh of the stem is made up of generative hyphae running lengthways (that is, up and down the stem). The cells are 5 to 8 μm wide, and are smooth and colourless; the cell walls up to 1 μm thick. They are dextrinoid. All
M. funalis hyphae lack
clamp connections.
Similar species Marasmius funalis differs from its closest relative,
M. liquidambari, due to the presence of cheilocystidia, the lack of clamp connections and the fact that the caulocystidia of
M. liquidambari do not form bristles; instead, they are club shaped to cylindrical. The species is known from Mexico and Papua New Guinea.
M. hudonii, known from Europe, is similar in appearance to
M. funalis. However, the former has a cap covered in hairs or bristles, and differs microscopically; for instance, the hyphae feature clamp connections. ==Distribution and ecology==