Laccaria amethystina, commonly known as the amethyst deceiver, is a small brightly colored mushroom, that grows in deciduous as well as coniferous forests. The mushroom itself is edible, but can absorb arsenic from the soil. Because its bright amethyst coloration fades with age and weathering, it becomes difficult to identify, hence the common name ‘Deceiver’. This common name is shared with its close relation Laccaria laccata that also fades and weathers. It is found mainly in Northern temperate zones, though it is reported to occur in tropical Central and South America as well. Recently, some of the other species in the genus have been given the common name of "deceiver".
Description & appearance
The cap is 1–6 cm in diameter, and is initially convex, later flattening, and often with a central depression (navel). When moist it is a deep purplish lilac, which fades upon drying out. It is sometimes slightly scurfy at the center, and has pale striations at the margin.
Electronmicroscopic image of spores of Laccaria amethystina. The stem is the same colour as the cap, and has whitish fibrils at the base, which become mealy at the top. It is fibrous, hollow, fairly tough when rolled in the fingers, with dimensions of 0.6 to 7 centimetres (0.24 to 2.76 in) long by 0.1 to 0.7 centimetres (0.039 to 0.276 in) thick. The flesh is without a distinctive taste or smell, and is thin, with pale lilac coloration. The gills are colored as the cap, often quite distantly spaced, and are dusted by the white spores; their attachment to the stem is sinuate—having a concave indentation before attaching to the stem.
The spores are spherical and hyaline, and bear pointed spines (echinulate) that are long relative to the size of the spore; they typically have dimensions of 7–10 by 7–10 µm. The basidia, the spore-bearing cells, are club-shaped and hyaline, and are 30–64.5 by 8.5–14 µm .
Distribution & habitat
L. amethystina is a common species in most temperate zones of Europe, Asia, Central, South, and eastern North America. It grows solitary to scattered with a variety of deciduous and coniferous trees, with which it is mycorrhizally associated, though it most commonly occurs with trees in the Fagales. It appears in late summer to early winter, and often with beech; in Central and South America, it more commonly grows in association with oak. Research has shown that L. amethystina is a so-called "ammonia fungus", an ecological classification referring to those fungi that grow abundantly on soil after the addition of ammonia, or other nitrogen-containing material; the congeneric species Laccaria bicolor is also an ammonia fungus.