AMANITA: CHARACTERISTICS, REPRODUCTION, NUTRITION, SPECIES - BIOLOGY - 2025

Amanita is a genus of agaric fungi (Basidiomycota, Agaricales) belonging to the Amanitaceae family, which is characterized because its fruiting body has a partial veil and a universal veil, the blades are separated from the stipe and its spores are white. Additionally, the stipe hyphae are long and club or mallet shaped.

This genus has a wide distribution worldwide and its species establish mycorrhizal relationships with trees of various species. Researchers estimate that there are about 1,000 species of Amanita in the world, of which about half have yet to be described to science.

Edible mushroom species Amanita caesarea. Taken and edited from: Vihljun

Some species of Amanita are edible and highly appreciated by mushroom lovers. A large quantity of these species must be cooked very well, as raw they are toxic. The best known of the edible species is Amanita cesarea, considered by some the queen of wild mushrooms for its flavor and texture.

However, other species are highly toxic, even after cooking, and are responsible for more than 90% of mushroom poisoning, with some fatal results.

characteristics

An exclusive characteristic of the group is observed in its development, since before producing the fruiting bodies they produce buttons of compact tissue inside which the crown, laminae, stipe and base are formed, which then will expand and emerge, breaking the tissue that forms them. surrounds. This phenomenon is called schizohimenial development.

Another characteristic is that they have both universal and partial veils. The first of these comprises the outer layer of tissue that is seen around the button. After breaking the button, the remnants of the universal veil can form small and regular fragments on the cap or crown (warts).

It can also remain as a single irregularly shaped piece on top of the crown (patch), and lastly, the universal veil can remain as a sac-like structure surrounding the base of the fruiting body, which is called the volva.

The partial veil covers the blades, extending between the stipe and the hat of young specimens, breaking when spore production begins. The remains of the partial veil may remain on the margin of the hat, or on the stipe, sometimes forming a ring.

The blades in Amanita are not attached to the stipe or only touch it very lightly and a white spore is produced in each of them.

Additionally, the Amanita, like the other members of the Amanithacea family, present a stipe formed by large, mallet-shaped cells oriented vertically.

Taxonomy

The genus Amanita belongs to the Basidiomycota division, Agaricomycetes class, Agaricales order and to the Amanitaceae family. This family also contains the genus Limacella, whose representatives are very similar to those of the genus Amanita, and also Catatrama, a genus that contains only three species.

In 1760, the Polish-German mycologist George Rudolf Boehm coined the name Amanita, however he used it to describe a species that actually belonged to the genus Agaricus. The first valid use of the name was made by Christian Hendrik Persoon in 1797, and therefore this is considered the author of the taxon.

The taxonomy of the genus is complex and some taxonomists divide it into two subgenera, each with numerous sections. According to other taxonomists, the genus is divided into seven sections: Amanita, Caesareae, Vaginatae, Amidella, Lepidella, Phalloideae, and Validae.

The type species of the genus is Amanita muscaria, and there are currently about 600 other validly described species, but mycologists believe that there may be a similar number of species not yet discovered.

Reproduction

Asexual reproduction can occur in the genus Amanita through fragmentation of the mycelium, while in sexual reproduction it occurs, as in the rest of the basidiomycetes, by the formation of haploid basidiospores.

This last type of reproduction occurs in two stages, first the germination of the basidiospores will occur, forming haploid hyphae. These spores can come from the same sporophor (self-fertilization) or from different sporophores (interfertilization) but they must be sexually compatible.

When two sexually compatible hyphae meet, plasmogamy occurs, that is, the cellular protoplasms of the hyphae unite, but fusion of the nuclei does not occur. The result is a mycelium made up of cells with two hapolid nuclei, or dicariont.

The final stage of sexual reproduction occurs much later, with the appearance of the fruiting bodies. In the basidia located in the laminae of the fruiting bodies, karyogamy of the pairs of haploid nuclei of each cell will occur. Karyogamy gives rise to a short-lived zygote that undergoes meiosis and produces four haploid spores.

Nutrition

Most Amanita species establish mycorrhizal relationships with different tree species. These fungi obtain water and minerals from the environment, which they exchange with their hosts for already prepared nutrients, mainly carbohydrates.

The host plant obtains from this ratio more water and minerals than it could obtain by itself and additionally obtains protection against other fungi, many of which could be potentially pathogenic.

Mycologists have also reported the existence of some Amanita species that are saprophytes. In other words, they feed on decomposing organic matter. They have even pointed out that there are also species that can be described as saprophytic or facultative mycorrhizal.

The latter can thrive in the absence of trees, but can also establish mycorrhizal relationships with trees when they are available in the environment where the fungi develop.

Examples of representative species

The genus Amanita is one of the most diverse genera of fungi, most of the almost 600 known species are toxic, even some considered the most toxic in the world, with a probability of death of between 10% and 60% of cases. There are also species with psychoactive properties in even some highly appreciated edible ones.

- Edible species

Amanita caesarea

It is known as Caesar's mushroom, oronja or king's egg. Its fruiting body has a cap up to 20 cm in diameter, which is originally hemispherical and flattens out over time.

Its blades and stipe are of an intense ocher color and it has a large, white and membranous volva. You can establish relationships with trees of different species such as conifers, chestnut trees, cork oaks, holm oaks and oaks.

The fruiting body appears between summer and autumn in southern Europe and can be confused with Amanita muscaria, from which it differs because the latter has white plates and stipe instead of ocher.

Its flavor and aroma are very pleasant and it can even be consumed raw.

Amanita rubescens

Mushroom known by the name of reddish amanita. It presents a reddish hemispherical hat that flattens over time. Its blades are white, while the foot varies from whitish to pale pink. It grows in all types of soils, often associated with pine forests and heaths.

It gives off a very pleasant aroma and its meat, with a sweet taste, is white in color and turns reddish when cut.

This species contains substances known as hemolysins that destroy red blood cells, so it should not be consumed raw. Some researchers even argue that its consumption should be avoided even when cooked, as hemolysins can resist thermal shocks.

However, it is still one of the Amanita species most appreciated by mushroom lovers.

Amanita rubescens. Taken and edited from: Karelj.

Other edible species

There are many other species of mushrooms of this genus that are edible, such as Amanita ponderosa, A. jacksonii, A. maireii, A. vaginata, A. zambiana, among others; but in general, scientists suggest avoiding their consumption as they are easily confused with toxic species.

- Toxic species

Amanita muscaria

This species, known as false oronja or fly agaric, is the best known species of Amanita, and perhaps of mushrooms in general. This is because it is the fungus that is traditionally associated with goblins and fairy tales.

Its fruiting body features a cap that is initially hemispherical and bright red in color and flattens and turns orange over time. Traces of white veil remain on the hat. The stipe is ringed and white or cream in color, while the blades are whitish-brown in color.

This species contains psychoactive alkaloids with hallucinogenic properties and has been used in rites of different religions in different parts of the world. It has numerous toxic substances, including muscimol, muscazone and muscaridine.

Although infrequent, human deaths have occurred due to ingestion, mainly in children and the elderly. There is no treatment for this type of poisoning.

Amanita phalloides

Known as the death mushroom, it is the deadliest species of mushroom for humans. One of the causes of the high number of deaths due to this mushroom is that it is easily confused with some edible species.

This mushroom has a hemispherical cap that flattens over time and can reach up to 15 cm in diameter. Its color is olive green, lighter towards the edges, although some specimens may be lighter and even white.

The blades are slightly greyish and the foot is ringed and white with irregularly arranged greenish scales.

The toxins in this fungus affect the liver and kidneys and can cause a syndrome called phallodian, which is slow-acting and difficult to identify. It can also cause liver failure. Liver transplantation is generally necessary when phallodian syndrome occurs. There is an antidote developed by the Pasteur Institute, but it is of limited efficacy.

Amanita phalloides. Taken and edited from: I.slobodan at Serbian Wikipedia

Other toxic species

Other Amanita species known for their toxicity include Amanita panterina, A. verna, and A. virosa, among many others.

References

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3. The genus Amanita. Recovered from: Mushroomexpert.com.
4. # 172: The genus Amanita. In Fungus fact. Recovered from: fungusfactfriday.com.
5. T. Oda, C. Tanaka & M. Tsuda (2004). Molecular phylogeny and biogeography of the widely distributed Amanita species, A. muscaria and A. pant henna. Mycological Research.
6. C. Lyre. Amanita muscaria: characteristics, life cycle, nutrition, reproduction, consumption and effects. Recovered from: lifeder.com.