Melanoleuca melaleuca

Description

Melanoleuca melaleuca is a species of mushroom in the family Tricholomataceae, and it is the type species of its genus Melanoleuca. It is difficult to distinguish from other related species firstly because it is variable, secondly because the taxonomic criteria are often based on characteristics that have later been found to be variable, and thirdly because there is much disagreement between authorities as to exactly how the species should be defined.

More often seen in grassland than the very similar Common Cavalier Melanoleuca polioleuca with which it is easily confused, this 'cavalier' mushroom has no generally accepted common name even though it is commonly recorded.

This mushroom is reported to be edible but nothing special; however, as these kinds of mushrooms are notoriously difficult to identify Ultimate Mushroom does not recommend collecting them for food.

Synonyms

1. Tricholoma melaleucum (Pers.) P. Kumm., 1871

2. Gyrophila melaleuca (Pers.) Quél., 1886

3. Melaleuca vulgaris Pat., 1887

4. Boletopsis melaleuca (Pers.) Fayod, 1889

5. Melanoleuca vulgaris (Pat.) Pat., 1897

Mushroom Identification

1. Cap

   3.5 – 8 cm, low convex, often with a low umbo, smooth, dark brown fading to grayish brown.

2. Gills

   Whitish, crowded, emarginately attached to the stipe.

3. Stipe

   Up to 10 cm long and typically 1 cm thick, similarly colored to the cap but lighter, with longitudinal fibers.

4. Spores

   6.5 - 8.5 x 5 - 6 µm, elliptical with amyloid warts (staining blue in Melzer's reagent), spore print white.

5. Odor

   Faint.

6. Habitat

   Grassy places in woods, roadsides, heathland, etc.

7. Similar Species

   The Common Cavalier Melanoleuca polioleuca is macroscopically indistinguishable with certainty from Melanoleuca melaleuca, but it can be separated by microscopic examination of the spores, cystidia, etc. Its spores are more elongated (they have a larger ratio of major to minor diameter, which in mycologists refer to as having a lower Q factor) and it has pointed fusiform gill-edge cystidia, which are absent in Melanoleuca melaleuca.

History

This mushroom was described in 1801 by Christiaan Hendrik Persoon, who established its basionym when he gave it the binomial scientific name Agaricus melaleucus.

It was American mycologist William Alphonso Murrill (1869 - 1957) who in 1911 transferred this species to its present genus, thereby establishing its currently accepted scientific name Melanoleuca melaleuca.

Melanoleuca melaleuca is the type species of the genus Melanoleuca, a very difficult group of about 50 species that even professional mycologists struggle with.

The genus name Melanoleuca comes from the Ancient Greek words melas meaning black, and leucos meaning white. No cavalier mushroom is truly black and white, but many have caps whose upper surfaces are various shades of gray-brown, with whitish gills beneath. As is sometimes the case with the type species of a genus, the specific epithet melaleuca is essentially a restatement of the generic name.

Photo sources:

Photo 1 - Author: Huafang (CC BY-SA 3.0)

Photo 2 - Author: James Baker (cepecity) (CC BY-SA 3.0)

Photo 3 - Author: Jerzy Opioła (CC BY-SA 3.0)

Photo 4 - Author: Eva Skific (Evica) (CC BY-SA 3.0)