American Caesar’s Mushroom (Amanita jacksonii)

August 25^th. I was driving home when I spotted a cluster of mushrooms at the edge of the woods by the road. I knew immediately that they were Caesar’s Amanita (Amanita jacksonii) mushrooms. What surprised me was the size of the largest one. Its cap was 7 to 8 inches in diameter, the largest I had ever seen.

The cluster, from different angles.

The caps of the buds are oval. As they open, the caps become convex, then flat, and finally depressed as are the larger mushrooms in this cluster.

The caps of these mushrooms are solid red, without any scales. Mature caps on these mushrooms have marked striations from the margin towards the center.

Their gills are yellow and crowded, and free from their stems.

Their stems taper slightly from the base to the top and are yellow (or orange) with orange-red fibers, often in zones. Stems have a yellow-to-orange ‘skirtlike’ ring. In addition, one of the most striking things about this mushroom is that the remains of the volva – the membrane that encases the growing mushroom – are often visible at the base of the stem, even when the mushroom is mature. 

These mushrooms may be found east of the Great Plains in the United States where they have a mycorrhizal relationship with the roots oaks and pines. They fruit in summer and fall.

Identification resources: 

- Michael Kuo, MushroomExpert.com: Amanita jacksonii 

- Roger’s Mushrooms: Amanita jacksonii 

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