The mushroom veils.
1. The Universal veil.
The earliest macroscopically visible indication of a new fruiting body may be a small ovoid egg
or button which has a protective membrane – the universal veil.
As the fruiting body grows the veil ruptures but remnants may remain at the base of the stem
as the volva or on the top of the cap in the form of a large central patch, small
scattered scales or warts, or as a powder.
2. The Partial and marginal veils.
Some Basidiomycetes, especially the Agarics, have a second or partial veil which extends
from the stem to the edge of the cap to protect the young gills.
When it ruptures it may leave remnants around the stem (the ring or annulus) or tags around
the cap edge known as the marginal veil.
Some mushrooms have no veils, some have one or the other and some have both.
They sometimes disappear as the mushroom ages.