|gills on hymenium|
|cap is convex|
|hymenium is free|
|stipe has a ring and volva|
|spore print is white|
|ecology is mycorrhizal|
|edibility: choice but not recommended|
Amanita caesarea, commonly known in English as Caesar's Mushroom, is a highly regarded edible mushroom in the genus Amanita, native to southern Europe and North Africa. It has a distinctive orange cap, yellow gills and stem. Similar orange-capped species occur in North America and India. It was known to and valued by the Ancient Romans, who called it Boletus, a name now applied to a very different type of fungus.
Taxonomy and naming
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 favorite of the Roman emperors, who took the name Caesar (originally a family name) as a title. The Romans called it Bōlētus, derived from the Ancient Greek βωλιτης 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. Other common names include Amanite de César and Oronge.
It has also been classified as A. umbonata. A. hemibapha is a similar species originally described from India, and this name has sometimes been applied to North American collections. The relationship of the similar North American species A. arkansana and A. jacksonii to A. caesarea is not clear. The edibility of some of these similar species is also unclear, though A. jacksonii is eaten by many and there have been no reports of illness from it.
This mushroom has an orange-red cap, initially hemispherical before convex and finally flat. The surface is smooth, and margins striated, and it can reach 15 (6 in) or rarely 20 cm (8 in) in diameter. The free gills are pale to golden yellow, as is the cylinder-shaped stipe, which is 8–15 cm (3-6 in) tall and 2–3 cm ( around 1 in) wide. The ring hangs loosely and is lined above and smooth below. The base of the stipe is thicker than the top and is seated in a greyish-white cup-like volva, which is a remnant of universal veil. The spores are white.
It could be confused with the poisonous fly agaric (Amanita muscaria). Though A. muscaria has a distinctive red cap dotted with fluffy white flakes, these tend to fall off as the carpophor ages and the bright red tends to fade to a yellowy orange. The latter mushroom will always have white gills and stalk with a ringed volva  rather than a yellow stalk and is most common in birch woods. Certain varieties ( eg. Amanita muscaria var. guessowii ) are much close to yellow even at the juvenile stage.
Distribution and habitat
This mushroom fruits in oak woodland, sometimes mixed with conifers, from early summer to mid autumn. It is found in North Africa and southern Europe, particularly in the hills of northern Italy. It is thought to have been introduced north of the Alps by the Roman armies as it is most frequently found along old Roman roads. The mushroom is also distributed in Hungary, India, and China (Sichuan Province). Although the species is not known to exist in the United States and Canada, it has been collected in Mexico.
This mushroom is highly prized, and is a common sight in the markets of Italy, southern France, and Spain. However, many mycologists warn inexperienced gatherers against seeking it out as it can be easily confused with other deadly members of the Amanita family.
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