Yema de huevo: what the wild mushroom is and how to use it

What is it?

The yema de huevo mushroom, also known as yemita or hongo dorado, is a wild edible 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 takes its popular name from the characteristic intense yellow colour of the cap and gills, which recall 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 gathered during the rainy season, from July to October, in states such as the State of 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 older and forms part of the ancestral ethnomycological knowledge of the Nahua, Otomí, 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 the Mexican forests. Sahagún recorded in Book XI of the Florentine Codex various mushrooms eaten by the Mexica, among which references to edible yellow mushrooms may 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 markets of the highlands under names such as yema de huevo, yemita, hongo dorado or also tecomate in some regions, reflecting 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 glossy, 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, remains of the universal veil. This volva, together with the uniform yellow colour, is one of the key identifying features. The flesh is pale yellow, firm and pleasantly scented. 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 cooking of the Mexican highlands it is prepared roasted on the comal with salt, stewed with epazote and lard, in mixiotes wrapped with guajillo chilli, batter-fried with egg or in soups with maize masa. Its flavour is delicate, slightly sweet, with notes of butter, nut and a faint citrus edge, much appreciated by gastronomes and traditional gatherers.

Cultural significance

The 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 underlines the importance of the temperate Mexican forests as reservoirs of biodiversity unique in the world. It forms part of the rich repertoire of wild mushrooms that sustains the traditional Mexican cuisine inscribed in 2010 by UNESCO as Intangible Cultural Heritage of Humanity. Its gathering is an important economic activity for farming 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 each August and September. Research by the UNAM Institute of Biology and INECOL has deepened understanding of its ecology, its nutritional value (high in protein and B-group vitamins) and its economic importance. Contemporary Mexican cuisine in signature restaurants has re-evaluated this endemic mushroom as an identity ingredient of the country, alongside other unique mycological species such as huitlacoche.

Frequently asked questions