Major Groups > True Morels and Verpas

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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:

  • "Gray morels," in the sense of eastern North American collectors, were not supported as separate species; they are merely immature forms of yellow morels like Morchella esculentoides ("gray morels" in the sense of commercial collectors in western North America correspond to Morchella tomentosa).
  • "Pickles" and "greenies," often separated as putative species by commercial collectors in western North America on the basis of their colors, were not supported; several morel species demonstrate green colors.
  • "Morchella crassipes" in the sense of North American field guide authors--namely, a yellow morel with an enormous, inflated stem--was not supported; specimens matching this description merely represented mature specimens of yellow morels that had remained unpicked for long periods of time in warm, wet weather conditions.

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.


 		 

Verpa bohemica

Morchella sp

Morchella tomentosa

Morchella esculentoides

Morchella prava

Morchella capitata


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Key to Verpas and DNA-Defined True Morels in North America


1.Cap attached to the stem only at the very top, hanging like a thimble on the end of a pencil (slice the mushroom in half to view it in cross-section); mushroom essentially hollow, but often containing wispy, cotton-candy-like fibers inside.
2

1.Cap more or less fully attached to the stem--or attached about halfway down; mushroom essentially hollow, the interior lacking wispy, cotton-candy-like fibers.
3


2.Cap smooth or with vague, irregular wrinkles; mushroom small to medium in size (3-11 cm tall) when mature; asci 8-spored; spores 20–40 µm long.

2.Cap deeply and prominently wrinkled; mushroom sometimes larger than above when mature; asci 2-spored; spores 45–85 µm long.


3.Cap attached to the stem roughly halfway up, with a substantial portion hanging "free"; mature stem often long in proportion to cap; stem often fragile.
4

3.Cap more or less completely attached to the stem--with, at most, a shallow rim at the point of attachment; mature stem proportionally long or not; stem fragile or not.
5


4.Appearing in western North America under black cottonwoods in riverine ecosystems.

4.Appearing east of the Rocky Mountains under various hardwoods, in various ecosystems.


5.Appearing in landscaping settings, primarily along the West Coast in winter and spring but also very rarely in midwestern and eastern North America in fall or spring.
6

5.Appearing in natural ecosystems.
8


6.Young cap usually distinctively pointed; young pits dark, contrasting with pale ridges; young surfaces bruising reddish orange to salmon; mature pits and ridges dull yellow.

6.Not completely as above.
7


7.Mature ridges dark brown to black; mature pits brownish; pits and ridges elaborately developed in laddered vertical channels.

7.Not completely as above.
8


8.Ridges (ignore the pits) dark gray to brown or black when young, or pale when young and darkening to brown or black with maturity.
9

8.Ridges pale yellowish or pale brownish throughout development.
15


9.Appearing in conifer burn sites in western North America (or, rarely, in jack pine burn sites above the Great Lakes), usually within a year or two of the fire.
10

9.Not found in conifer burn sites; variously distributed.
12


10.Surfaces densely and conspicuously velvety, especially when young; cap and stem usually dark gray to black but sometimes becoming pale in direct sunlight at high elevations; projecting hairs (120-250+ µ) present, brown in KOH.

10.Surfaces bald or very finely velvety with a lens; projecting hairs lacking.
11


11.Stem often chambered and layered internally; elements on sterile ridges primarily capitate (often strikingly so).

11.Stem usually not as above; elements on sterile ridges variously shaped but not usually capitate. Note: Morchella sextelata and Morchella septimelata cannot be separated morphologically.


12.Found from the Rocky Mountains westward.
13

12.Found from the Great Plains eastward.
14


13.Mature stem usually strikingly ridged and pocketed; ridges on cap pale yellowish when young.

13.Stem not usually strikingly ridged and pocketed; ridges on cap dark brown to black when young.


14.Appearing from roughly 44° N latitude northward; mushroom 4-7 cm high at maturity; spores usually 20-22 µ long.

14.Widely distributed east of the Great plains; mushroom 5-14+ cm high at maturity; spores usually 22-27 µ long.


15.Found in conifer burn sites in western North America; cap and stem conspicuously velvety when young; projecting hairs (120-250+ µ) present, brown in KOH. Note: This species is usually dark gray to black but can sometimes fade in direct sunlight at high elevations.

15.Ecosystem varying; cap and stem not velvety; projecting hairs absent.
16


16.Cap usually conic or nearly so; cap attached to the stem with a small but noticeable groove or sinus (reminiscent of a race track for ants).
17

16.Cap conic or not; cap attached to the stem directly, without a groove.
18


17.Mature stem usually strikingly ridged and pocketed; ridges on cap usually darkening with maturity or when dried.

17.Mature stem not strikingly ridged and pocketed; ridges on cap not darkening with maturity or when dried.


18.Mature mushrooms small to medium in size (3-12 cm high); pits and ridges primarily vertically arranged; distributed east of the Great Plains.
19

18.Mature mushrooms medium sized to large (5-22+ cm high); pits more randomly arranged; variously distributed.
20


19.Cap usually egg-shaped, with a rounded or bluntly conic apex; mature mushroom 5-13 cm high; southeastern in distribution; possibly limited to association with tulip trees.

19.Cap usually pointed; mature mushroom 3-9 cm high; widely distributed east of the Great Plains and south of the Great Lakes; associated with various hardwoods, including tulip trees, green ash, white ash, and others.


20.Pits and ridges contorted, asymmetrical, and irregular; ridges often remaining flattened or widely rounded into maturity; often (but not always) found in sandy soil near lakes and rivers.

20.Pits and ridges not as above; ecology varying.
21


21.Distributed in the Great Lakes region from Ontario to Illinois and Virginia; morphologically inseparable from Morchella esculentoides.

21.Widely distributed in North America; morphologically inseparable from Morchella cryptica.



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.

Morchella atrotomentosa (Moser) Bride; invalid name
Morchella crassistipa Snyder; doubtful name
Morchella hotsonii Snyder; insufficiently known
Morchella species Mel-8; insufficiently known

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.



References


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Kuo, M. (2012, November). The Morchellaceae: True morels and verpas. Retrieved from the MushroomExpert.Com Web site: http://www.mushroomexpert.com/morchellaceae.html