Laccaria amethystina is a tallogill of the genus Laccaria, which is a family of small to medium hygrophanous mushrooms. The term hygrophanous refers to the ability of a mushroom to change its color as it ages, sometimes making it difficult to identify[i]. This hygrophanous ability of the Laccaria amethystina has earned it its common name of the “amethyst deceiver”. However, the epithet “deceiver” is more appropriately linked with its cousin Laccaria laccata, which is a highly variable and deceptive mushroom. To make things even more “deceiving”, Laccaria amethystina and Laccaria laccata favor similar habitats, and are often found growing next to each other in small clusters. Furthermore, the similarity is so great that the Laccaria amethystina was once even thought to be a mere variant of Laccaria laccata.
The designation amethystina in Laccaria amethystina refers to the violet(amethyst) coloring of the fresh cap of this tallogill mushroom.
The first known description of the Amethyst Deceiver occurred in 1778 by the English botanist William Hudson. Hudson named the mushroom Agaricus amethystinus, as most gilled mushrooms in the early days of fungal taxonomy belonged to the Agaricus genus. It was not until 1884 that the Amethyst Deceiver was reclassified into its current genus by Mordecai Cubitt Cooke, a famous British mycologist.
The Laccaria genus of tallogill mushrooms are edible, including the Laccaria amethystina. Although they are not frequently used in dishes because it takes rather a lot of them to make a good meal, and they are often quite small and tedious to collect in adequate quantities. Additionally, only the caps of Laccaria amethystina can be employed while cooking as their stems are tough and inedible.
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Identification and Description
As mentioned, the Laccaria genus, including Laccaria amethystina, is hygrophanous and can be quite variable in appearance depending on the age of the mushroom as well as the weather conditions.
Cap: The cap is 2-7cm(0.8-2.7in) in diameter. When young, the caps are convex or dome-shaped, but as they age they become flattened or depressed in the center with upturned edges, resembling a shallow funnel. The surface of the cap is smooth at first, later becoming roughened as it breaks to form soft, somewhat powdery scales. When the mushroom is young or moist, the cap will be violet to deep purple with streaking near its margins; as the mushroom ages(or dries) it will fade to a light reddish purple, then become a reddish brown, and finally paler and eventually almost white as the purple color disappears.
Gills: The gills are widely spaced. They can be either adenate(broadly attached to stalk) or decurrent(running down the stalk). The color of the gills often matches the color of the cap, but the purple/violet coloration tends to persist longer on the gills than on the cap.
Stem: The stem is 4-10cm high and 1-7mm thick. The shape is cylindrical and equal or slightly swollen at the base. The stem itself is tough and fibrous, often twisted, and hollow at maturity. Near the base, the stems are “hairy; and lastly, the coloration of the stem matches that of the cap or may be slightly lighter.
Smell and Taste: nondistinctive mushroom-like scent and taste.
Spores: The spores are white in color; roughly spherical with diameter of 8–11µm; and are covered in spines up to 1.5um tall.
Spore Print: The spore print, which refers to the powdery deposit on the surface underneath, is white or flushed with pale violet.
Edibility: The Laccaria genus of tallogill mushrooms are all edible, including Laccaria amethystina, but not frequently employed while cooking.
Habitat and Range: The Laccaria amethystina can be found growing in temperate climates of Europe, Asia and Americas during late summer through to early winter. In North America, this mushroom is widely distributed east of the Rocky Mountains. Although they can be found growing alone, scattered, or gregariously in leaf litter in all kinds of woodland, they can be found in particular abundance underneath beech and oak trees.
Look-Alikes
Due to the fact that Laccaria amethystina is a hygrophanous mushroom it can resemble a variety of other mushrooms throughout its life cycle.
Most frequently, Laccaria amethystina may be confused for Laccaria laccata the true “deceiver” or other tallogill Laccaria species, making recognition and differentiation quite difficult.
Another potential look-alike, is the deadly Inocybe geophylla lilacina or the Lilac fibrecap. The Lilac fibrecap can be differentiated from the Amethyst deceiver by its gills. The gills of the Lilac fibrecap are off white to gray, whereas the amethyst deceiver has the same color gills as the cap and stem.
Yet another look-alike is the Mycena pura. This is a purple coloured bonnet mushroom, but can be differentiated from Amethyst deceiver by its pale gills and a soft, non-fibrous stem.
Toxicity, Safety & Side Effects
The Laccaria amethystina is not toxic itself. However, if grown in areas polluted with arsenic, this heavy metal may accumulate and reach toxic concentrations within the flesh of the mushroom. For example, a study conducted in South West China that evaluated arsenic concentrations and associated health risks in Laccaria mushrooms found that consumption of 300g fresh weight of Laccaria species for a single meal in a week yielded exposure values of arsenic higher than the limit dose for the intake of inorganic arsenic recommended by the Joint FAO/WHO Expert Committee on Food Additives.
Acute arsenic toxicity can present with garlic-like odor on the breath, nausea, vomiting, abdominal pain and diarrhea, as well as central nervous system manifestations such as seizures or coma. While chronic exposure to arsenic may lead to cancer of the lung, skin, and liver; and other pathognomonic signs such as thickening of skin on palms and soles as well as white bands across nails, known as mees lines.
References:
- Hall, I. R., Stephenson, S. L., Buchanan, P. K., Yun, W., & Cole, A. L. J. (2003). Edible and Poisonous Mushrooms of the World. Timber Press, Incorporated.
- McKnight, K. H., McKnight, V. B., & Peterson, R. T. (1998). A Field Guide to Mushrooms: North America (Peterson Field Guides) (Reissue,Subsequent ed.). Houghton Mifflin.
- Minter, D. W., Stalpers, J. A., Kirk, P. M., & Cannon, P. F. (2011). Dictionary of the Fungi (10th ed.). CABI.
- J. (2021b, November 10). Amethyst Deceiver Mushrooms (Laccaria amethystina) Identification. Totally Wild UK.
- Kuo, M. (2010) Laccaria amethystina. MushroomExpert.com
- Zhang, J., Li, T., Yang, Y. L., Liu, H. G., & Wang, Y. Z. (2015). Arsenic concentrations and associated health risks in Laccaria mushrooms from Yunnan (SW China). Biological trace element research, 164(2), 261–266.
