Amanita caesarea

Amanita caesarea, commonly known as Caesar's mushroom, is a species of fungus in the genus Amanita. While it was first described by Giovanni Antonio Scopoli in 1772, it was a favorite of early rulers of the Roman Empire.

The mushroom has a distinctive orange cap, yellow gills and stipe, and contains organic acids. The species resembles poisonous species including fly agaric. A. caesarea is found in North Africa, Eurasia, and North America. It is edible, given correct identification.

Amanita caesarea was first described by Italian mycologist Giovanni Antonio Scopoli in 1772 as Agaricus caesareus, before later being placed in Amanita by Persoon in 1801. The common name comes from its being a favourite of the Roman emperors, who took the name Caesar (originally a family name) as a title. It was a personal favorite of Roman emperor Claudius. The Romans called it Bōlētus, derived from the Ancient Greek βωλίτης for this fungus as named by Galen. Several modern common names recognise this heritage with the English Caesar's mushroom and royal amanita, French impériale, Polish cesarski and German Kaiserling. In Italian, it is ovolo (pl. ovoli), due to its resemblance to an egg when very young. In Albanian it is kuqëlorja from its colour (< Albanian kuqe 'red'). Other common names include Amanite des Césars and Oronge.

A. caesarea was first domesticated in 1984.

This mushroom has an orange to red cap, initially hemispherical before convex and finally flat, reaching 20 centimetres (8 inches) in diameter. The surface is smooth, with striated margins. The gills are adnexed or free, close, and yellowish. The similarly colored (or slightly paler) stipe is 5–15 cm (2–6 in) tall and 1.5–3 cm (1⁄2–1+1⁄4 in) wide. The ring hangs loosely and is often striate. The base of the stipe is equal or bulged and seated in a white cup-like volva, a remnant of universal veil. The spores are white, producing a white to faintly yellow spore print.

A study of isolates from the fruit bodies of A. caesarea showed that the radial growth (increases in axon's diameter) of this species was possible at pH 6–7, and optimal growth was in a temperature of 24–28 °C (75–82 °F), depending on the isolate.

An investigation of the heavy metal content of mushroom samples found cadmium levels in A. caesarea four times greater than allowed in cultivated mushrooms by European Union standards. The amount of lead in A. caesarea also exceeded allowed levels. The study concluded that the accumulation of heavy metals may be a species-specific property of mushrooms, and that chronic consumption of some mushroom types could potentially be harmful.

A study of the organic acid composition of mushrooms found a relatively high level, about 6 g/kg, in A. caesarea. Malic acid, ascorbic acid, citric acid, ketoglutaric acid, fumaric acid, shikimic acid and traces of succinic acid were detected. Malic and ascorbic acids were the most abundant compounds. Ergosterol has also been isolated from A. caesarea.