Noun
A saclike envelope of certain fungi, which bursts open as the plant develops.
Source: Webster's dictionaryAmanita section Amanita includes the species which have very patchy universal veil remnants, including a volva that is reduced to a series of concentric rings and the veil remnants on the cap to a series of patches or warts. Source: Internet
Many mushrooms lack a universal veil, therefore they do not have either a volva or volval patches. Source: Internet