Right around the turn of September, staff here at the garden noticed these viscerally impressive giant mushrooms emerging from leaf litter beneath a western red cedar and evergreen oak in the David C. Lam Asian Garden. Then the slugs discovered it. Then we photographed it. Who else is eating this? It strikes me that the study of fungivory remains wide open. Perhaps some readers might have some personal experiences.
The giant agaric (also known as “The Prince”), Agaricus augustus, grows to about 30cm wide. It is collected all over the Northern Hemisphere, where gourmands prize it as much for its “meaty” flavor as for its bulk. If the generic name sounds familiar, that’s because this species is in the same genus as the supermarket button mushroom, Agaricus bisporus.
In these pictures, you can see the dark, spore-bearing gills lining the underside of a fully-opened cap. Younger stages would have lighter gills and a dome-shaped cap. The pattern of brown tissue on the surface of the cap is a product of the older surface cells darkening with age while the underlying mass of younger cells continues to expand, isolating the patches of older cells.