What You Should Know
Leucopaxillus giganteus (formerly as the giant clitocybe) is a large chunky mushroom that can be found in fairly large numbers and is edible to most but can cause gastric upsets in some. The fruit body can be quite large — the cap reaches diameters of up to 50 cm (20 in). It has a white or pale cream cap, and is funnel-shaped when mature, with the gills running down the length of the stem.
This species has a cosmopolitan distribution and is typically found growing in groups or rings in grassy pastures, roadside hedges, or woodland clearings. It has been shown to contain a bioactive compound with antibiotic properties.
Mainly seen beside hedgerows or on woodland edges, the Leucopaxillus giganteus can also occur on parkland and in permanent pastures and occasionally on grassy roadside verges.
Almost pure ivory white when young, turning buff from the center at maturity.
Other names: Giant Funnel, Giant Leucopax.
Leucopaxillus giganteus Mushroom Identification
Saprobic; growing alone, scattered, or in large arcs and fairy rings in open woods and woodland clearings with trees present; sometimes in the disturbed ground; summer and fall; common in the Pacific Northwest and Rocky Mountains, but widely distributed in North America.
8-50 cm; at first convex, then flat, eventually developing a central depression and becoming somewhat vase-shaped; dry; smooth; the margin inrolled at first, later wavy and sometimes obscurely lined; fragile in age; whitish at first, but buff to tan by maturity.
Running down the stem; crowded; whitish or buff, becoming nearly tan in age; some forking.
4-10 cm long; up to 6 cm thick; more or less equal; dry; whitish, with tiny fibers that darken in age; base with copious white mycelium.
Whitish; proportionally thin in age.
Odor and Taste
Taste pleasant, foul, or mealy; odor similar.
Spores 6-8 x 3-4.5 µ; elliptical; smooth; weakly amyloid. Cystidia absent. Clamp connections present.
Leucopaxillus giganteus Look-Alikes
This latter species has a darker coloring and is found more commonly in montane regions.
May be distinguished by its nauseous odor, the tan color of the cap, and the adnate (gill squarely attached to the stem) to slightly adnexed (narrowly attached) gills.
Tends to be smaller, with a cap diameter ranging from 6 to 30 cm (2.4 to 11.8 in) broad.
Have been suggested as additional lookalike species. Young specimens of Leucopaxillus giganteus may be confused with Clitocybe irina, C. praemagna or C. robusta. White Lactarius and Russula species may also appear superficially similar, but they have brittle flesh that breaks cleanly, unlike the fibrous flesh of Leucopaxillus giganteus.
The Common Funnel, is much smaller; its spores are inamyloid, and they are pip shaped rather than ellipsoidal.
The Trooping Funnel, is usually smaller but with a much taller stem; its spores are inamyloid.
Leucopaxillus giganteus Bioactive Compounds
Leucopaxillus giganteus contains a bioactive compound named clitocine that has antibiotic activity against several bacteria that are pathogenic to humans, such as Bacillus cereus and Bacillus subtilis; an earlier (1945) study showed antibiotic activity against Mycobacterium tuberculosis, Salmonella typhi, and Brucea abortus. Clitocine has also been shown to promote apoptosis (cell death) in human cervical cancer cells in vitro (HeLa). The mycelia of L. giganteus, when grown in liquid culture, has been shown to produce phenols and flavonoids that have antioxidant activity.
Leucopaxillus giganteus Taxonomy and Etymology
This massive mushroom was first described in 1794 by the Oxford (England) botanist John Sibthorp (1758 - 1796), who named it Agaricus giganteus. The currently-accepted scientific name dates from 1938, when German-born mycologist Rolf Singer moved the Giant Funnel to the new (at that time) genus Leucopaxillus.
The name Leucopaxillus giganteus was given to this species in 1872 by French mycologist Lucien Quélet. Two years later Elias Magnus Fries renamed it Paxillus giganteus. Other synonyms include Agaricus giganteus Sibth., and Aspropaxillus giganteus (Sibth.) Kühner & Maire.
Leucopaxillus is derived from the Greek Leucos meaning white and Paxillus, the name of a genus that includes the toxic toadstool Paxillus involutus.
The specific epithet giganteus hardly needs explanation, as this is a gigantic mushroom.
Photo 1 - Author: James Lindsey (Creative Commons Attribution-Share Alike 2.5 Generic)
Photo 2 - Author: Liz Popich (Lizzie) (Creative Commons Attribution-Share Alike 3.0 Unported)
Photo 3 - Author: Ian Alexander (Creative Commons Attribution-Share Alike 4.0 International)
Photo 4 - Author: Liz Popich (Lizzie) (Creative Commons Attribution-Share Alike 3.0 Unported)