The ivory waxcap, Hygrophorus eburneus (Bull.) Fr.
Agaricus eburneus Bull.
Gymnopus eburneus (Bull.) Gray
Hygrophorus cossus sensu auct.; fide Checklist of Basidiomycota of Great Britain and Ireland (2005)
Hygrophorus eburneus (Bull.) Fr.
Limacium eburneum (Bull.) P. Kumm.
Cap: 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.
Flesh: white, soft, thick at the disc, thin elsewhere, unchanging; odor and taste mild.
Gills: subdecurrent to decurrent, subdistant, moderately broad, waxy, white, sometimes faintly yellow in age.
Stipe: 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.
Spores: 6.5-8 x 3.5-5 µm, smooth, elliptical.
Spore print: white.
Habitat: solitary to subgregarious in hardwood and conifer woods; fruiting in Sept.-Oct. Widespread in Europe and North America.
Eight unusual fatty acids with bactericidal and fungicidal activity have been isolated from Hygrophorus eburneus (Teichert et al., 2005). These fatty acids, which all contain a so-called γ-crotonate partial structure, are named as follows:
(2E 11Z)-4-oxooctadeca-2,11,17-trienoic acid
(2E, 9E)-4-oxooetadeca-2,9-dienoic acid
(2E, 11Z)-4-oxooetadeca-2,1 I-dienoic acid
A recent study from Greece analyzed the metal contents of eight indigenous mushroom species, including H. eburneus. The metal concentrations, given as µg/g, dry weight basis, are summarized in the table below (mean ± standard deviation):
To help give these values more significance, the second row of the table gives the daily metal intakes by a normal 60 kg consumer, in mg/serving (assuming a serving size of 30 g, dry weight). The authors conclude that the intake of potentially toxic heavy metals (i.e. Pb, Cd and As) by consumption of 30 grams of H. eburneus (dry weight) poses no risk for the consumer. Furthermore, this mushroom can be used in a well-balanced diet due to the high contents of functional minerals (Ouzouni et al., 2007).
California fungi has links to several more pictures.