Bleeding fairy helmet

Appearance

The fruit bodies of "Mycena haematopus" are the reproductive structures produced by cellular threads or hyphae which grow in rotting wood. The shape of the cap of the fruit body will vary depending on its maturity.

Young caps, or "buttons", are ovoid to conical; later they are campanulate, and as the fruit body matures, the margins lift upward so that the cap becomes somewhat flat with an umbo.

The fully grown cap can reach up to 4 cm in diameter. The surface of the cap initially appears dry and covered with what appears to be a very fine whitish powder, but it soon becomes polished and moist. Mature caps appear somewhat translucent, and develop radial grooves mirroring the position of the gills underneath.

The color of the cap is reddish- or pinkish-brown, often tinged with violet, and paler towards the edge. The margin is wavy like the edge of a scallop, and may appear ragged because of lingering remnants of the partial veil.

The mushroom flesh can range from pale to the color of red wine, and has no distinctive odor. It oozes a red latex when cut. The gills have an adnate attachment to the stem, meaning they are more or less directly attached to it.

They are initially whitish or "grayish vinaceous" in color, and can develop reddish-brown stains. Between 20 and 30 gills reach from the cap edge to the stem, resulting in a gill spacing that is described as "close to subdistant"—gaps are visible between adjacent gills. There are additional gills, called lamellulae, that do not extend directly from the margin to the stem; these are arranged in two or three series of equal length.

The stem is up to 9 cm tall and 0.1 to 0.2 cm thick, hollow and brittle, and a dark reddish-brown color. In young fruit bodies, the upper part of the stem is densely covered with a pale cinnamon-colored powder which wears off with age. The stem has a mass of coarse hairs at the base. Like the cap, the stem also bleeds a red latex when it is cut or broken.

The spore print is white. The spores are elliptical, smooth, with dimensions of 8–11 by 5–7 µm. They are amyloid, meaning they will absorb iodine when stained with Melzer's reagent. The spore-bearing cells are 4-spored.

Sterile cells called cystidia are numerous on the edges on the gills; they measure 33–60 µm by 9–12 µm. Cystidia that are present on the stipe appear in clusters, and clublike to irregular in shape, measuring 20–55 by 3.5–12.5 µm. The gill tissue contains numerous lactifers, cells that produce the latex that is secreted when it is cut.

The surface mycelium of "M. haematopus" is whitish and fluffy. Swelling at the terminal tips of hyphae is present, but not very abundant, and moniliform hyphae are very rare. Bioluminescence is present, but weak. Extracellular oxidase enzymes are present, consistent with its ecological role as a saprobe.

Naming

The species was initially named "Agaricus haematopus" by Christian Hendrik Persoon in 1799, and later sanctioned under this name by Elias Magnus Fries in his 1821 "Systema Mycologicum". In the classification of Fries, only a few genera were named, and most agaric mushrooms were grouped in "Agaricus", which was organized into a large number of tribes.

"Mycena haematopus" gained its current name in 1871 when the German fungal taxonomist Paul Kummer raised many of Fries' "Agaricus" tribes to the level of genus, including "Mycena". In 1909 Franklin Sumner Earle placed the species in "Galactopus", a genus that is no longer considered separate from "Mycena".

"Mycena haematopus" is placed in the section "Lactipedes", a grouping of Mycenas characterized by the presence of a milky or colored latex in the stem and flesh of the cap. The specific epithet is derived from Ancient Greek roots meaning "blood" and "foot". It is commonly known as the blood-foot mushroom, the bleeding fairy helmet, the burgundydrop bonnet, or the bleeding Mycena.

Distribution

"Mycena haematopus" obtains nutrients from decomposing organic matter and the fruit bodies can typically be found growing on stumps and well-decayed logs, usually in groups that are joined together by a common base.

The decomposition of woody debris on the forest floor is the result of the combined activity of a community of fungal species. In the sequential succession of mushrooms species, "M. haematopus" is a "late colonizer" fungus: its fruit bodies appear after the wood has first been decayed by white rot species. The initial stage of wood decay by white rot fungi involves the breakdown of "acid-unhydrolyzable residue" and holocellulose.

Predators

"Mycena haematopus" can be parasitized by "Spinellus fusiger", another fungal species which gives the mushroom a strikingly hairy appearance.