Don’t expect that there is a sack on the base of every amanita. This is a false impression given by crude explanations in some field guides. Volvas have many textures and many different internal structures, which result in their breaking up in so many different forms of warts and powder and membranes, etc.

Volva = the outerlayer that develops as protection while the rest of the fruiting body develops.

Volva does not = bulb.

Most bulbs are tissue that remains in a somewhat “primitive” or “undeveloped” state while the stem takes on the the particular internal structure that is peculiar to only Amanita and Limacella…baseball bat shaped cells aligned vertically and acting as “inverted pile drivers” to expand the stem rapidly with hydrostatic pressure. Bulbs are said to exist in species in which the cap and stem develop in the upper part of the early “button” stage of development (primordium).

There is no bulb in the species of some sections in which the stem develops and expands totally from a central point in the primordium. These are the amanitas with totally elongating stems (sections Vaginatae, Caesareae, and a good chunk of sect. Amidella).

Rod