Yema de huevo: yellow mushroom of Mexican forests

What is it?

The yema de huevo mushroom, also known as yemita or hongo dorado, is an edible wild mushroom belonging to the species Amanita basii, a species endemic to Mexico formally described in 1985 by the ethnomycologists Gastón Guzmán and Joaquín Cifuentes Blanco. It owes its popular name to the characteristic intense yellow colour of the cap and gills, reminiscent of the yolk of a boiled egg. It grows in temperate oak, pine and fir forests of the central Mexican highlands, in mycorrhizal symbiosis with these trees. It is harvested during the rainy season, from July to October, in states such as Mexico, Tlaxcala, Puebla, Hidalgo and Veracruz. It belongs to the genus Amanita, which also includes deadly toxic species, so its identification requires expert knowledge. It is considered one of the finest wild mushrooms of the Mexican highlands and forms part of the rich traditional ethnomycological heritage.

Origin and history

Amanita basii was formally described as a species endemic to Mexico by Gastón Guzmán and Joaquín Cifuentes in 1985, dedicated to Dr Teófilo Herrera Suárez, a pioneer of Mexican mycology. However, its traditional consumption in the central highlands is much earlier and forms part of the ancestral ethnomycological knowledge of the Nahua, Otomi, Mazahua and Totonac peoples. Before its formal scientific description, this mushroom had been confused with the European Amanita caesarea (tecomate), but later morphological and genetic studies confirmed that it is a distinct species exclusive to Mexican forests. Sahagún recorded in Book XI of the Florentine Codex various mushrooms consumed by the Mexica, among which references to edible yellow mushrooms can be found. The name tlaltlacuit appears in some colonial manuscripts in reference to forest mushrooms. CONABIO documents Amanita basii as a species of great ethnomycological importance, recorded in rural highland markets under names such as yema de huevo, yemita, hongo dorado or also tecomate in some regions, which reflects the diversity of Mexican popular nomenclature.

Characteristic ingredients

Amanita basii is a basidiomycete fungus of the family Amanitaceae, endemic to the temperate forests of Mexico. Its cap is convex when young and later flattened, of intense yellow to orange colour, smooth and shiny, with a diameter between 6 and 18 centimetres. The gills are yellow and free from the stem, and the stem is golden yellow with a membranous ring and a white volva at the base, remnants of the universal veil. This volva, together with the uniform yellow coloration, is one of the key identifying features. The flesh is pale yellow, firm and pleasantly aromatic. It is essential to distinguish it from deadly species of the same genus: A. phalloides (death cap) and A. virosa (destroying angel) are completely white or greenish with white flesh and white gills. Expert identification is absolutely necessary. In the traditional cuisine of the Mexican highlands it is prepared roasted on the comal with salt, stewed with epazote and lard, in mixiotes wrapped with chile guajillo, battered with egg or in soups with maize dough. Its flavour is delicate, sweetish, with notes of butter, nut and slightly citrus, much appreciated by gastronomes and traditional harvesters.

Cultural significance

Yema de huevo is an emblem of Mexico's endemic mycological biodiversity and one of the most prized mushrooms of the national ethnomycological heritage. As an endemic species, its existence underscores the importance of Mexican temperate forests as reservoirs of biodiversity unique in the world. It forms part of the rich repertoire of wild mushrooms that sustains traditional Mexican cuisine inscribed in 2010 by UNESCO as Intangible Cultural Heritage of Humanity. Its harvesting is an important economic activity for peasant women of the highlands, who sell it fresh in rural markets such as those of Tlaxco, Acaxochitlán, Cuajimalpa, Ozumba and San Juan de las Huertas during the wild mushroom fairs held every August and September. Research by the Institute of Biology of UNAM and INECOL has further explored its ecology, its nutritional value (high content of protein and B group vitamins) and its economic importance. Contemporary Mexican cuisine in signature restaurants has revalued this endemic mushroom as an identity ingredient of the country, alongside other unique mycological species such as huitlacoche.

Frequently asked questions

What is the difference between yema de huevo and tecomate?

Although they are traditionally confused, they are distinct species. The yema de huevo (Amanita basii) is endemic to Mexico, while the tecomate or hongo cesáreo (Amanita caesarea) is native to Europe and North America. The yema de huevo has a more intense and uniform yellow colour; the tecomate is usually more orange. Morphological and genetic studies confirmed in 1985 their identity as separate species.

What does the yema de huevo mushroom taste like?

It has a delicate, sweetish and refined flavour, with notes of butter, toasted nut and a slightly citrus background. The cooked texture is firm, fleshy and juicy, similar to the European tecomate. It is neither bitter nor spicy. It combines exceptionally well with lard, butter, epazote, dried chile guajillo, garlic, onion and lime, ingredients that enhance its aromatic profile without masking it.

How is yema de huevo served?

Traditionally it is prepared roasted on the comal with salt and lime to appreciate its delicate flavour; stewed with epazote, garlic and lard; in mixiotes with chile guajillo and pasilla; battered with egg and bathed in tomato sauce; or sautéed with butter in contemporary preparations. Its elegant flavour makes it a star ingredient in fine soups and egg scrambles in the rural cuisine of the highlands.

Where does the yema de huevo mushroom originate from?

Amanita basii is a species endemic to Mexico, which means it occurs naturally only in this country. Its main distribution areas are the temperate pine, oak and fir forests of the central highlands: State of Mexico, Tlaxcala, Puebla, Hidalgo and Veracruz, where it fruits between July and October during the rainy season. It forms mycorrhizal associations with forest trees that it requires to grow.