Melanoleuca polioleuca
Description
Melanoleuca polioleuca has a dark cap covering pallid gills, this is a tricky species to identify from macroscopic features alone; it occurs in deciduous broadleaf woodland and with conifers, notably pines, and it is a saprobic fungus (feeding on rotting wood and other organic vegetation).
It is very difficult to separate this species from some of the other brown-capped cavaliers such as Melanoleuca melaleuca, with more broadly ellipsoidal spores and no gill-edge cystidia.
This mushroom is reported as being edible but nothing special.
Common names: Common Cavalier.
Mushroom Identification
Cap
The appearance of caps is very variable from specimen to specimen and varies even more through the development life of the fruitbody. The cap is initially convex with a downturned margin, eventually flattening and sometimes developing a central depression, usually with a small umbo; smooth; slightly greasy; dark gray-brown when moist, turning paler in dry weather; 4 to 8cm across when fully expanded.
Gills
Sinuate; white, turning creamy-gray with age.
Stem
The stem is generally much longer than the cap diameter - often by as much as a factor of two. 4 to 10cm long and 0.5 to 1cm diameter; base slightly bulbous; white, covered in gray-brown fibrils that are densest towards base; no stem ring.
Spores
Ellipsoidal, densely warty, 6.5-9 x 4-5μm; amyloid.
Spore Print
Very pale cream.
Odor and Taste
Odor faintly mealy; taste mild but not distinctive.
Habitat & Ecological Role
On soil among leaf litter in all kinds of woods and forests and near trees in lawns and parks.
Season
July to November.
Similar Species
Melanoleuca melaleuca is macroscopically indistinguishable with certainty from the Common Cavalier, but it can be separated by microscopic examination of the spores, cystidia, etc. Its spores are more broadly ellipsoidal (they have a lower ratio of major to minor diameter, which mycologists refer to as having a lower Q factor) and it lacks gill-edge cystidia, which are present in Melanoleuca polioleuca.
History
In 1821 the Sweddish mycologist Elias Magnus Fries described this species and gave it the name Agaricus polioleucus.
In 1934 it was transferred to the genus Melanoleuca by German mycologist Robert Kühner (1903 - 1996) and French mycologist René Charles Joseph Ernest Maire (1878 - 1949).
Synonyms of Melanoleuca polioleuca include Agaricus polioleucus Fr., Tricholoma melaleucum var. polioleucum (Fr.) Gillet, Melaleuca vulgaris Pat., Tricholoma polioleucum (Fr.) Sacc., Melanoleuca vulgaris (Pat.) Pat., and Melanoleuca polioleuca f. polioleuca (Fr.) Kühner & Maire.
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 brown, with whitish gills beneath.
The specific epithet come from poli- meaning grey or hoary, and leucos meaning black.
Photo sources:
Photo 1 - Author: Strobilomyces (CC BY-SA 3.0)
Photo 2 - Author: amadej trnkoczy (amadej) (CC BY-SA 3.0)
Photo 3 - Author: amadej trnkoczy (amadej) (CC BY-SA 3.0)
Photo 4 - Author: Richard Daniel (RichardDaniel) (CC BY-SA 3.0)
