|Major Groups > True Morels and Verpas|
The Morchellaceae: True Morels and Verpas
[ Ascomycetes > Pezizales . . . ]
by Michael Kuo
The Morchellaceae family includes the true morels (members of the genus Morchella), the verpas (in the genus Verpa), and the cup fungi in the genus Disciotis. Under the microscope, these mushrooms all have asci that do not turn blue in iodine, and spores that are smooth, elliptical, and have homogeneous contents. Another defining feature of the family is the large number of nuclei (20-60) found in Morchellaceae spores.
Over the last decade or so, visitors to this web site helped sharpen our understanding of the genus Morchella by contributing hundreds of well documented morel collections to the now closed Morel Data Collection Project (MDCP). As a result of study of these collections, along with collections from herbaria and other sources, several papers were published (O'Donnell and collaborators, 2011; Kuo and collaborators, 2012) hypothesizing the evolution of morels and describing 19 DNA-defined species (14 of which were new) in North America.
There are undoubtedly more North American morels to be discovered, but the species described by Kuo and collaborators are probably the most commonly encountered; they are keyed out below. Unfortunately the species are not always "morphologically distinct," which means they can't always be identified by looking at their physical features. But when geographic distribution information is added to the picture, only a few frustrating identification dilemmas remain (see couplets 11 and 21 in the key below).
Identification characters for Morchella are primarily macroscopic, and involve careful observation of the cap and stem. Microscopic features are informative in a few cases, and include spore size and the morphology of the paraphysis-like elements on the morel's sterile ridges. For a thorough discussion of morphological characters in Morchella see the Supplementary Materials of the Kuo and collaborators publication. As is usually the case with mushroom identification, you will need to have a nice, large collection of fruiting bodies representing both immature and mature stages of development in order to have much success.
DNA study of MDCP specimens by Carol Carter and by Kerry O'Donnell exposed several morphological misconceptions about North American morels:
Results reported in O'Donnell and collaborators (2011) and delineated morphologically in Kuo and collaborators (2012) support the idea that the genus Morchella contains three major evolutionary groups, or "clades." The first contains Morchella rufobrunnea only and is therefore labeled the rufobrunnea clade; the second, the esculenta clade, contains 5 species in North America; the final clade, the elata clade, contains 14 North American representatives. Fortunately for traditionalists, the esculenta and elata clades correspond in great part to the concepts of "yellow morels" and "black morels" found in previous treatments--with some exceptions (especially regarding Morchella frustrata and Morchella snyderi).
The world still awaits contemporary study of the rest of the Morchellaceae. In the genus Verpa, two morphological species are currently accepted; they are keyed out below, with the morels. However, it would not surprise me at all if results from DNA studies of verpas were to parallel those of the morels, leading to the naming of North American species. The same may be said of the cup fungi in Disciotis. For now, however, Disciotis venosa is the only accepted North American species; I have keyed it in the key to cup fungi.
Key to Verpas and DNA-Defined True Morels in North America
Insufficiently Known Species, Excluded Species, and Doubtful Names
The species below represent invalid names or names that cannot currently be applied to North American morels with scientific accuracy; follow the links for detailed explanations.
The names Morchella conica, Morchella crassipes, Morchella deliciosa, Morchella esculenta, Morchella elata, and Morchella semilibera, often used in North American field guides, are European names; due to high continental endemism in Morchella (demonstrated by O'Donnell and collaborators, 2011), these names can safely be discarded as applying to North American morels.
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Cite this page as:
Kuo, M. (2012, November). The Morchellaceae: True morels and verpas. Retrieved from the MushroomExpert.Com Web site: http://www.mushroomexpert.com/morchellaceae.html