Giant funnel

Appearance

The cap of ''L. giganteus'' can become rather large, up to 40 cm in diameter with a thickness of 1 to 1.2 cm at half the radius. Younger specimens have caps that are convex, with a margin that is rolled downwards, but as the mushrooms matures the cap flattens out and eventually becomes shallowly funnel-shaped. The cap is smooth and creamy white in color, but may develop brown stains and circular cracks with age.

The cream-colored gills are narrow, crowded close together, and have a decurrent attachment—running down the length of the stem; in age the gills will darken to a buff color. The stem is off-white with reddish-brown fibers and has dimensions, when mature, of up to 4.5 to 6 cm tall by 1.5 to 3 cm thick. There is no ring on the stem. At the base of the stem there is typically a dense, white mycelium that may form a mat. The flesh is firm, and also is white. Mature specimens are fragile, and difficult to remove from the ground without breaking.When viewed in deposit, such as with a spore print, the spores appear white. When viewed with a light microscope, the spores are ovoid to ellipsoid, translucent , have a smooth surface, and possess a broadly rounded apex and base; the spore dimensions are 6–8 by 3.5–5 µm. Like all ''Leucopaxillus'' species, the spores of ''L. giganteus'' are amyloid—meaning that they will absorb iodine when stained with Melzer's reagent—however, the extent of the stain may be variable. The spore-bearing cells, the basidia, are 25–40 by 4.5–8 µm, narrowly club-shaped, and are attached to either 2 or 4 spores. The hyphae of this species invariably have clamp connections.

Naming

''Leucopaxillus giganteus'' somewhat resembles ''Leucopaxillus candidus'', but this latter species has a darker coloring and is found more commonly in montane regions. ''Leucopaxillus septentrionalis'' is also large and resembles ''L. giganteus'' at some points during its development, but may be distinguished by its nauseous odor, the tan color of the cap, and the adnate to slightly adnexed gills. ''Leucopaxillus candidus'' tends to be smaller, with a cap diameter ranging from 6 to 20 cm broad. Both ''Leucopaxillus gentianeus'' and ''Lactarius vellereus'' 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''.

Distribution

''Leucopaxillus giganteus'' can form fairy rings in grassy areas like pastures, and is also found along roadsides; it produces fruiting bodies in summer and autumn. It is a saprobic species, and so derives nutrients by decomposing organic matter.

The fungus has a cosmopolitan distribution, and occurs throughout the temperate zone of the northern hemisphere. It is found in North America, Britain, and Europe. David Arora reports that in North America, it is most common in the Pacific Northwest and the Rocky Mountains.

Habitat

''Leucopaxillus giganteus'' can form fairy rings in grassy areas like pastures, and is also found along roadsides; it produces fruiting bodies in summer and autumn. It is a saprobic species, and so derives nutrients by decomposing organic matter.

The fungus has a cosmopolitan distribution, and occurs throughout the temperate zone of the northern hemisphere. It is found in North America, Britain, and Europe. David Arora reports that in North America, it is most common in the Pacific Northwest and the Rocky Mountains.