Caesar’s mushroom: Amanita caesarea


Amanita caesarea is a very popular edible mushroom which is known and used as food for more than 2000 years. The early Roman Emperors were very fond of this delicacy, which is what inspired the latin name.

Amanita caesarea is an ectomycorrhizal fungus that establish natural symbiotic relationships with both, trees (Quercus, Castanea, Pinus) and shrubs (Arbutus, Cistus). It is a specie of the Mediterranean region, frequent in Southern Europe and less common in other European countries. It has also been collected in North Africa, Asia and Mexico, being this the only record for the Americas.

Caesar’s mushrooms fruiting bodies have an Agaricoid shape, i.e. a gilled mushroom with a central cap and stem, and always present a distinct ring and volva. But, the most obvious feature is its bright orange cap. Fruiting bodies usually appear from October to November in the Mediterranean region, in both siliceous and calcareous soils.

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Quercus suber stand, Margens do Sol Posto, Portugal, 2014, ©José Raposo


Caesar’s mushroom is a termophilous species which fruits from October to November in the Mediterranean region under Oak trees (Quercus ilex and Q. ilex subsp. rotundifolia, Q. pubescens, Q. suber, Q. robur, Q. pyrenaica and Q. coccifera), Chestnut trees (Castanea Sativa), Pine trees (Pinus halepensis, P. pinaster, P. radiata), Fagus sylvatica, Carpinus spp., Arbutus unedo, Cistus spp., Calluna vulgaris and Genista scorpius, over a broad range of soil pH.

It has a bright smooth orange-red cap with striated margin, initially hemispherical then convex and finally flattened. The cap can reach 15 cm or rarely 20 cm in diameter. The gills are pale to golden yellow, free and crowded. The stipe is also yellow and is cylinder-shaped with 8–15 cm tall and 2–3 cm wide. The yellow 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 sac-like volva, which is a remnant of universal veil. The spore deposit is white.

It could be confused with the poisonous fly agaric (Amanita muscaria) which has a distinctive red cap, dotted with fluffy white flakes (that frequently tend to fall off as the carpophore ages) and a white stipe and ring.