Photo by F. Ankie Camacho
Major parts of a fruiting body
What are fruiting bodies and how are they produced?
The objects commonly referred to as morels, cup-fungi, and truffles are only one part of their respective fungal organisms, much as apples are only a part of the apple tree. Rather than call the morels, cup-fungi, and truffles "fruits", the terms "fruit body," "fruiting body," and "mushroom" are often used in general discussions; a variety of technical terms may be encountered for them as well including sporocarp, or, for the Pezizales and their relatives, ascocarp or ascoma. In most mushroom-producing fungi, the nutrient-gathering phase or mycelium is composed of very thin threadlike elements called hyphae too thin to be seen individually without a microscope. Mycelia produce fruiting bodies under conditions that vary from species to species.
Technical characters, many of which can only be evaluated through the use of a compound light microscope, underlie the division of fungi into smaller groups. However, one can learn a lot about fungi and identify many of the Pezizales to genus or even species using only one's powers of observation supplemented by a hand lens or magnifying glass. An important part of making identifications is to learn the limits of accuracy one can expect with the tools and references available. For those who eat mushrooms, lives, or at very least, a good night's sleep, depend on the accuracy of identifications the mushrooms eaten.
Some of the theoretical and technical background is presented here for general information. Beginners are urged to concentrate on the discussions of field characters for identifying these fungi, and to learn where field characters do not provide reliable means of distinguishing one group from another.
Most "mushrooms" are produced either by ascus-bearing fungi or basidium-bearing fungi. Asci and basidia are specialized cells in which a series of events occurs that involves the fusion, replication, and redistribution of genetic material followed by the formation of spores. These events can not be observed without a microscope and special stains. However, the cells in which the process occurs and in or on which the spores are formed are distinctive. Furthermore, the fruiting bodies produced by the two types of mushrooms are typically sufficiently different that one can predict relatively easily to which group a given specimen belongs. The ascus-bearing fungi are members of the Ascomycotina also called Ascomycetes, Ascomycota or, in scientific slang, the ascos; the basidium-bearing fungi are members of the Basidiomycotina also called Basidiomycetes, Basidiomycota, or, in scientific slang, the basidios. Asci resemble balloons that, depending on the species, may be long and cylindrical or nearly globose and in most Pezizales contain 8 ascospores while basidia resemble clubs typically with 4 prongs on them with one basidiospore formed on each prong. In the cup-fungi and morels, the asci typically are on the uppermost surface of the fruiting body while in the true (ascus-bearing) truffles they are usually enclosed within the fruiting body. In the basidium-bearing mushrooms that might be confused with members of the Pezizales, the basidia typically are on the lower side of an expanded cap, over the surface of an irregular club or column or, in the false (basidium-bearing) truffles, enclosed within the fruiting body.
If a microscope is available, and the specimens are mature, it is usually a simple matter to determine whether the fungus is an ascomycete or a basidiomycete. In the absence of a microscope one has to use other clue that are less reliable to decide whether a given specimen is or is not a member of the Pezizales.
In order to compare and contrast the Pezizales with other mushrooms, first become familiar with the basic terms used to describe the major types of fruiting bodies and their parts. Additional, and more extensive, discussions about the morphology and anatomy of these fungi are presented in a number of the suggested references.
The characters are discussed under these headings: