The peridium is the protective layer that encloses a mass of spores in

fungi A fungus (: fungi , , , or ; or funguses) is any member of the group of eukaryotic organisms that includes microorganisms such as yeasts and mold (fungus), molds, as well as the more familiar mushrooms. These organisms are classified as one ...

. This outer covering is a distinctive feature of gasteroid fungi.

Description

Depending on the species, the peridium may vary from being paper-thin to thick and rubbery or even hard. Typically, peridia consist of one to three layers. If there is only a single layer, it is called a peridium. If two layers are present, the outer layer is called the exoperidium and the inner layer the endoperidium. If three layers are present, they are the exoperidium, the mesoperidium and the endoperidium. In the simplest subterranean forms, the peridium remains closed until the spores are mature, and even then shows no special arrangement for dehiscence or opening, but has to decay before the

spore In biology, a spore is a unit of sexual reproduction, sexual (in fungi) or asexual reproduction that may be adapted for biological dispersal, dispersal and for survival, often for extended periods of time, in unfavourable conditions. Spores fo ...

s are liberated.

Puffballs

For most fungi, the peridium is ornamented with scales or spines. In species that become raised above ground during their development, generally known as the "

puffball Puffballs are a type of fungus featuring a ball-shaped fruit body that (when mature) bursts on contact or impact, releasing a cloud of dust-like spores into the surrounding area. Puffballs belong to the division Basidiomycota and encompass sever ...

s", the peridium is usually differentiated into two or more layers, where the outer layer is usually resolved into warts or spines. In contrast, the inner layer remains continuous and smooth to preserve the

s. Sometimes, as in the case of '' Geaster'', the number of layers is greater, and the exoperidium eventually splits from the apexes into a variable number of pointed portions. However, the inner layer remains intact by a definite

aperture In optics, the aperture of an optical system (including a system consisting of a single lens) is the hole or opening that primarily limits light propagated through the system. More specifically, the entrance pupil as the front side image o ...

at the apex.

Earthballs

In contrast,

earthball ''Scleroderma'' is a genus of fungi, commonly known as earth balls, now known to belong to the Boletales order, in suborder (biology), suborder Sclerodermatineae. The best known species are ''Scleroderma citrinum, S. citrinum'' and ''Scleroder ...

fungi generally have only one peridium, which is 3–9 cm across. This lone peridium is generally rigid and rindlike; it is white when sectioned but pink if fresh. The surface varies from yellow brown to dingy yellow, and is arranged into scales.

Usage

The peridium is often given a specific name in particular species of

. For example, the peridium of mushrooms of the genus ''

Amanita The genus ''Amanita'' contains about 600 species of agarics, including some of the most toxic known mushrooms found worldwide, as well as some well-regarded Edible mushroom, edible species (and many species of unknown edibility). The genus is re ...

'' is called a volva. The peridium can also refer to the outer "nest" of a bird's-nest fungus.''Botany Illustrated: Introduction to Plants, Major Groups, Flowering Plant Families''; By Janice Glimn-Lacy, Peter B. Kaufman; page 53; Published by Birkhäuser, 2006; ,

References

{{Reflist Fungal morphology and anatomy