What You Should Know
Hygrophorus eburneus is a medium-sized, pure white, often remarkably slimy, fungus that is common in a variety of forest types throughout the PNW and elsewhere in the Northern Hemisphere. The closest look-alike is H. piceae Kühner, which differs by having a less slimy cap, dry to slightly viscid stipe, and frequent association with spruce. It also is widely distributed, but is less common than H. eburneus in many areas.
The Hygrophorus eburneus is mycorrhizal with Beech trees and with oaks. These woodwax fungi seem to be fairly tolerant of soil disturbance, as they sometimes appear on muddy tree-lined roadside verges.
This woodwax occurs in northern Africa, and it is also reported from many parts of North America where one of its common names is Cowboy's Handkerchief.
This mushroom is reported to be edible, but because of its relative scarcity (compared with many other edible woodland fungi), its sliminess and its small size, the Ivory Woodwax is not generally gathered for its culinary value.
Other names: Cowboy's Handkerchief, Ivory Waxy-Cap, Ivory Woodwax.
Hygrophorus eburneus Mushroom Identification
3-7 cm broad, convex with an inrolled margin, expanding to nearly plane with a low umbo or the disc depressed with an upturned margin; surface smooth to silky, slimy-viscid, white, occasionally faintly yellow in age.
white, soft, thick at the disc, thin elsewhere, unchanging; odor and taste mild.
Subdecurrent to decurrent, subdistant, moderately broad, waxy, white, sometimes faintly yellow in age.
4-10 cm tall, 0.5-1.5 cm thick, equal to tapering towards the base, often bent, stuffed, becoming hollow at maturity; surface finely scaled at the apex, smooth below, white, viscid; veil absent.
6.5-8 x 3.5-5 µm, smooth, elliptical.
Odor and Taste
Said by some authorities to smell like injured larvae of the Goat Moth, Cossus cossus, from which this woodwax’s synonymous name Hygrophorus cossus originated.
Solitary to subgregarious in hardwood and conifer woods; fruiting in Sept.-Oct. Widespread in Europe and North America.
Hygrophorus eburneus Look-Alikes
Is a common and gregarious little grassland mushroom with a white or ivory cap.
Is also similar in appearance, but has a smaller cap diameter of up to 4.5 cm (1.8 in)—and is not slimy. Hygrophorus cossus, which typically grows with Quercus species, differs in its pale pinkish-buff cap and gills, and has a distinct sour odor.
Does not have a potassium hydroxide reaction on the stem as does H. eburneus.
The "white slime mushroom" has non-waxy gills that are free from attachment to the stalk.
Hygrophorus eburneus Taxonomy and Etymology
The basionym of this species was established when it was described scientifically and named Agaricus eburneus by French biologist Jean Baptiste Francois (Pierre) Bulliard in 1782.
It was the great Swedish mycologist Elias Magnus Fries who, in 1836, renamed this woodwax mushroom Hygrophorus eburneus, which is the scientific name by which most mycologists refer to it today.
Synonyms of Hygrophorus eburneus include Agaricus eburneus Bull., Gymnopus eburneus (Bull.) Gray, and Hygrophorus eburneus var. eburneus (Bull.) Fr. (Often in the past this species has been treated as co-specific with Hygrophorus cossus.)
Hygrophorus eburneus is the type species of the genus Hygrophorus.
Hygrophorus, the genus name, comes from hygro- meaning moisture, and -phorus meaning bearer. Not only do these fungi contain a lot of water (as do most other mushrooms, of course) but they are also moist and sticky to touch.
The specific epithet eburneus means 'like ivory' - a reference (which is replicated in the English common name) to the off-white color of these woodwax fungi.
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