Chemical tests in mushroom identification
Encyclopedia
Chemical tests in mushroom identification are methods that aid in determining the variety of some fungi. The most useful tests are Melzer's reagent
and potassium hydroxide
.
can be used. A couple of drops are placed on the flesh. For example, Boletus spadiceus gives a fleeting blue to blue-green reaction.
and Bolete
identification. It is best to dissolve the salts in water (typically a 10% solution) and then apply to the flesh
, but it is sometimes possible to apply the dry salts directly to see a color change. For example, the white flesh of Boletus chrysenteron stains lemon-yellow or olive. Three results are expected with the iron salts tests: no change indicates a negative reaction; a color change to olive, green or blackish green; or a color change to reddish-pink.
and newspaper to test for the deadly poisonous amatoxin
s found in some species of Amanita
, Lepiota
, and Galerina
.
Psilocin
gives a positive Meixner test (100% false positive), therefore the Meixner test cannot differentiate between a hallucinogenic species and a deadly poisonous one.
can be used to test spores for amyloid
, nonamyloid, and dextrinoid.
This test is normally performed on white spored mushrooms. If the spores are not light colored, a change will not be readily apparent. It is easiest to see the color change under a microscope, but it is possible to see it with the naked eye with a good spore print.
Lyophyllum
the lamellae usually turn blue with the application of paradiaminobenzaldehyde (PDAB).
gives a color change in some species when applied to the cap or stem.
(KOH) gives a color change in some species:
(H2SO4) and vanillin
(vanilla). Used in Russula
identification.
Melzer's Reagent
Melzer's reagent is a chemical reagent used by mycologists to assist with the identification of fungi.-Composition:...
and potassium hydroxide
Potassium hydroxide
Potassium hydroxide is an inorganic compound with the formula KOH, commonly called caustic potash.Along with sodium hydroxide , this colorless solid is a prototypical strong base. It has many industrial and niche applications. Most applications exploit its reactivity toward acids and its corrosive...
.
Ammonia
Household ammoniaAmmonia
Ammonia is a compound of nitrogen and hydrogen with the formula . It is a colourless gas with a characteristic pungent odour. Ammonia contributes significantly to the nutritional needs of terrestrial organisms by serving as a precursor to food and fertilizers. Ammonia, either directly or...
can be used. A couple of drops are placed on the flesh. For example, Boletus spadiceus gives a fleeting blue to blue-green reaction.
Iron salts
Iron salts are used commonly in RussulaRussula
Around 750 worldwide species of mycorrhizal mushrooms compose the genus Russula. They are typically common, fairly large, and brightly colored - making them one of the most recognizable genera among mycologists and mushroom collectors...
and Bolete
Bolete
A bolete is a type of fungal fruiting body characterized by the presence of a pileus that is clearly differentiated from the stipe, with a spongy surface of pores on the underside of the pileus...
identification. It is best to dissolve the salts in water (typically a 10% solution) and then apply to the flesh
Trama (mycology)
In mycology trama is a term for the inner, fleshy portion of a mushroom's basidiocarp, or fruit body. It is distinct from the outer layer of tissue, known as the pileipellis or cuticle, and from the spore-bearing tissue layer known as the hymenium....
, but it is sometimes possible to apply the dry salts directly to see a color change. For example, the white flesh of Boletus chrysenteron stains lemon-yellow or olive. Three results are expected with the iron salts tests: no change indicates a negative reaction; a color change to olive, green or blackish green; or a color change to reddish-pink.
Meixner test for amatoxins
The Meixner test (also known as the Wieland Test) uses concentrated hydrochloric acidHydrochloric acid
Hydrochloric acid is a solution of hydrogen chloride in water, that is a highly corrosive, strong mineral acid with many industrial uses. It is found naturally in gastric acid....
and newspaper to test for the deadly poisonous amatoxin
Amatoxin
Amatoxins are a subgroup of at least eight toxic compounds found in several genera of poisonous mushrooms, most notably Amanita phalloides and several other members of the genus Amanita, as well as some Conocybe, Galerina and Lepiota mushroom species.-Structure:The compounds have a similar...
s found in some species of Amanita
Amanita
The genus Amanita contains about 600 species of agarics including some of the most toxic known mushrooms found worldwide. This genus is responsible for approximately 95% of the fatalities resulting from mushroom poisoning, with the death cap accounting for about 50% on its own...
, Lepiota
Lepiota
Lepiota is a genus of gilled mushrooms in the family Agaricaceae. All Lepiota species are ground-dwelling saprotrophs with a preference for rich, calcareous soils. Basidiocarps are agaricoid with whitish spores, typically with scaly caps and a ring on the stem. Around 400 species of Lepiota are...
, and Galerina
Galerina
Galerina is a genus of small brown-spored saprobic mushrooms, with over 300 species found throughout the world, from the far north to remote Macquarie Island in the Southern Ocean. Species are typically small and hygrophanous, with a slender and brittle stem. They are often found growing on wood,...
.
Psilocin
Psilocin
Psilocin , an aromatic compound, sometimes also spelled psilocine, psilocyn, or psilotsin, is a psychedelic mushroom alkaloid. It is found in most psychedelic mushrooms together with its phosphorylated counterpart psilocybin...
gives a positive Meixner test (100% false positive), therefore the Meixner test cannot differentiate between a hallucinogenic species and a deadly poisonous one.
Melzer's reagent
Melzer's ReagentMelzer's Reagent
Melzer's reagent is a chemical reagent used by mycologists to assist with the identification of fungi.-Composition:...
can be used to test spores for amyloid
Amyloid (mycology)
In mycology the term amyloid refers to a crude chemical test using iodine in either Melzer's reagent or Lugol's solution, to produce a black to blue-black positive reaction. It is called amyloid because starch gives a similar reaction, and that reaction for starch is also called an amyloid reaction...
, nonamyloid, and dextrinoid.
- Spores that stain bluish-gray to bluish-black are amyloid
- Spores that stain brown to reddish-brown are dextrinoid
This test is normally performed on white spored mushrooms. If the spores are not light colored, a change will not be readily apparent. It is easiest to see the color change under a microscope, but it is possible to see it with the naked eye with a good spore print.
Paradiaminobenzaldehyde
In the genusGenus
In biology, a genus is a low-level taxonomic rank used in the biological classification of living and fossil organisms, which is an example of definition by genus and differentia...
Lyophyllum
Lyophyllum
Lyophyllum is a genus of about 40 species of fungi, widespread in north temperate regions.-Species:*Lyophyllum connatum*Lyophyllum decastes*Lyophyllum eustygium*Lyophyllum favrei*Lyophyllum fumosum*Lyophyllum gangraenosum...
the lamellae usually turn blue with the application of paradiaminobenzaldehyde (PDAB).
Phenol
A 2–3% aqueous solution of phenolPhenol
Phenol, also known as carbolic acid, phenic acid, is an organic compound with the chemical formula C6H5OH. It is a white crystalline solid. The molecule consists of a phenyl , bonded to a hydroxyl group. It is produced on a large scale as a precursor to many materials and useful compounds...
gives a color change in some species when applied to the cap or stem.
Potassium hydroxide
A 3–10% solution of potassium hydroxidePotassium hydroxide
Potassium hydroxide is an inorganic compound with the formula KOH, commonly called caustic potash.Along with sodium hydroxide , this colorless solid is a prototypical strong base. It has many industrial and niche applications. Most applications exploit its reactivity toward acids and its corrosive...
(KOH) gives a color change in some species:
- In AgaricusAgaricusAgaricus is a large and important genus of mushrooms containing both edible and poisonous species, with possibly over 300 members worldwide...
, some species turn yellow with KOH, some have no reaction, and one species turns green. - Distinctive change for some species of CortinariusCortinariusCortinarius is a genus of mushrooms. It is suspected to be the largest genus of agarics, containing over 2000 different species and found worldwide. A common feature among all species in the genus Cortinarius is that young specimens have a cortina between the cap and the stem, hence the name,...
and Boletes
Sulfo-vanillin
Made from sulfuric acidSulfuric acid
Sulfuric acid is a strong mineral acid with the molecular formula . Its historical name is oil of vitriol. Pure sulfuric acid is a highly corrosive, colorless, viscous liquid. The salts of sulfuric acid are called sulfates...
(H2SO4) and vanillin
Vanillin
Vanillin is a phenolic aldehyde, an organic compound with the molecular formula C8H8O3. Its functional groups include aldehyde, ether, and phenol. It is the primary component of the extract of the vanilla bean. It is also found in Leptotes bicolor, roasted coffee and the Chinese red pine...
(vanilla). Used in Russula
Russula
Around 750 worldwide species of mycorrhizal mushrooms compose the genus Russula. They are typically common, fairly large, and brightly colored - making them one of the most recognizable genera among mycologists and mushroom collectors...
identification.