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Hygrophorus olivaceoalbus

[ Basidiomycetes > Agaricales > Tricholomataceae > Hygrophorus . . . ]

Taxonomy in Transition: Hygrophoroid/Omphalinoid > Hygrophoraceae Group

by Michael Kuo

Hygrophorus olivaceoalbus belongs to a group of fascinating waxy caps that feature not one but two veils protecting the young gills. The "inner veil" is composed of tiny threadlike fibers, and the "outer veil" is composed of thick slime. When the mushroom approaches maturity the cap expands to break the veils, which then are left to form a sheath around the stem.

In Hygrophorus olivaceoalbus the inner veil is brown to grayish brown, and easily seen. As the stem grows, the veil is pulled apart, resulting in stretched-looking concentric bands and, often, a thin and flimsy ring. The outer slime veil quickly dries out in warm conditions.


Ecology: Mycorrhizal with conifers--particularly with redwood and Sitka spruce on the West Coast, Engelmann spruce in the Rocky Mountains, and spruces or eastern hemlock in the northeast; growing scattered, gregariously, or in small clusters; late summer and fall (over winter in warmer climates); fairly widely distributed in northern and western North America.

Cap: 3-12 cm; convex when young, becoming broadly convex or more or less flat; slimy; with a streaked appearance from stretched-out fibers beneath the slime; dark brown to gray-brown; lighter towards the margin.

Gills: Attached to the stem or running down it; close or nearly distant; white; waxy.

Stem: 3-15 cm long; up to 3 cm thick; equal or with a somewhat swollen base; when fresh sheathed with slime over the lower portion; white at the apex; covered below the slime with brown fibers that stretch out as the mushroom grows and often become disposed as vaguely concentric stripes or bands by maturity; often with a fragile and imperfect or somewhat gelatinized ring.

Flesh: White; unchanging.

Odor and Taste: Not distinctive.

Spore Print: White.

Microscopic Features: Spores 9-12 x 5-6 µ; smooth; elliptical; inamyloid. Gill tissue divergent, with cells 3-8 µ wide. Pileipellis an ixocutis with clamp connections present.

REFERENCES: (Fries, 1815) Fries, 1838. (Hesler & Smith, 1963; Bird & Grund, 1979; Smith, Smith & Weber, 1979; Largent, 1985; Arora, 1986; Phillips, 1991/2005; Lincoff, 1992; McNeil, 2006.) Herb. Kuo 09040604.

A number of similar species and varieties have been named on the basis of minor differences in physical features; whether or not these taxa are actually genetically distinct has not been investigated, to my knowledge. I am treating Hygrophorus persoonii as more or less synonymous. See Hesler & Smith (1963) and Largent (1985) if you are interested.

Further Online Information:

Hygrophorus olivaceoalbus in Hesler & Smith (1963)
Hygrophorus olivaceoalbus at Roger's Mushrooms


Hygrophorus olivaceoalbus

Hygrophorus olivaceoalbus

Hygrophorus olivaceoalbus

Hygrophorus olivaceoalbus

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Kuo, M. (2007, January). Hygrophorus olivaceoalbus. Retrieved from the MushroomExpert.Com Web site: