The true morels (Morchella spp.) are among the edible fungi most prized by mushroom hunters. As with other mushrooms, the familiar morel is merely the spore-producing "fruiting body" of a macrofungus which exists mostly undergound. A variety of morel species fruit briefly and sporadically each spring across the northern hemisphere and information on when and where to find them is often closely guarded by collectors. Much lore exists (some of it surely well founded) about the microhabitats and weather conditions associated with the appearance of morels. Morels grow throughout the northern hemisphere in regions with temperate or boreal forests, as well as in some Mediterranean and subtropical regions such as coastal California, the highlands of Central American, and the Middle East. Morels also occur in the southern hemisphere and although many of these are believed to be introduced, there are apparently endemic species as well in, for example, Australia and southern South America. Morels are harvested from the wild commercially in several parts of the world, including the United States, Turkey, China, and the Indian subcontinent, although some progress has been made toward commercial cultivation. (Pilz et al. 2007 and references therein). Pilz et al. (2007) provide an overview of the biology and ecology of morels.
In recent years, a number of researchers have used molecular genetic approaches to help resolve questions about species boundaries and species diversity within the genus Morchella (e.g., O'Donnell et al. 2011; Du et al. 2012). Du et al. (2012) recognized more than five dozen putative Morchella species. Building on this work, Kuo et al. (2012) formally described a number of new phylogenetic species from the U.S. and Canada and reviewed their current understanding of the taxonomy and nomenclature of Morchella in the U.S. and Canada (Kuo et al. 2012 includes a dichotomous identification key). Much taxonomic work remains to be done on this challenging group, but it appears that the old idea that Morchella includes just a handful of very widely distributed species is unlikely to persist in the face of much new data indicating high levels of genetic diversity within geographic regions.
Although they are widely considered to be choice edibles and large numbers are eaten each year without ill effect, morels reportedly can be toxic, especially when poorly cooked, producing both gastrointestinal and neurological symptoms. Researchers investigating reports of Morchella toxicity concluded that these cases were not simply the result of confusion with the superficially similar and poisonous False Morel (Gyromitra esculenta) or other causes, but noted the need for further study to confirm and better understand the phenomenon of morel poisoning. (Saviuc et al 2010)
- Du, X.-H., Q. Zhao., Z.L. Yang, et al. 2012. How well do ITS rDNA sequences differentiate species of true morels (Morchella)? Mycologia 104(6): 1351-1368.
- Kuo, M., D.R. Dewsbury, K. O'Donnell, et al. 2012. Taxonomic revision of true morels (Morchella) in Canada and the United States. Mycologia 104(5): 1159–1177.
- O’Donnell, K., A.P. Rooney, G.L. Mills, et al. 2011. Phylogeny and historical biogeography of true morels (Morchella) reveals an early Cretaceous origin and high continental endemism and provincialism in the Holarctic. Fungal Genet Biol 48: 252–265.
- Pilz, D, R. McLain, Rebecca, S. Alexander, et al. 2007. Ecology and management of morels harvested from the forests of western North America. Gen. Tech. Rep. PNW-GTR-710. Portland, OR: U.S. Department of Agriculture, Forest Service, Pacific Northwest Research Station. 161 Pp.
- Saviuc, P., P. Harry, C. Pulce, et al. 2010. Can morels (Morchella sp.) induce a toxic neurological syndrome? Clinical Toxicology 48: 365-372.
Molecular Biology and Genetics
Statistics of barcoding coverage
Specimen Records: 467
Specimens with Sequences: 460
Specimens with Barcodes: 456
Species With Barcodes: 75
Public Records: 445
Public Species: 73
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Morchella, the true morels, is a genus of edible mushrooms closely related to anatomically simpler cup fungi. These distinctive mushrooms appear honeycomb-like in that the upper portion is composed of a network of ridges with pits between them. The ascocarps are prized by gourmet cooks, particularly for French cuisine. Commercial value aside, morels are hunted by thousands of people every year simply for their taste and the joy of the hunt.
Morels have been called by many local names; some of the more colorful include dryland fish, because when sliced lengthwise then breaded and fried, their outline resembles the shape of a fish; hickory chickens, as they are known in many parts of Kentucky; and merkels or miracles, based on a story of how a mountain family was saved from starvation by eating morels. In parts of West Virginia, they are known as "molly moochers." Other common names for morels include sponge mushroom. Genus Morchella is derived from morchel, an old German word for mushroom, while morel itself is derived from the Latin maurus meaning brown.
The fruit bodies of the Morchella are highly polymorphic in appearance, exhibiting variations in shape, color and size; this has contributed to uncertainties regarding taxonomy. Discriminating between the various species is complicated by uncertainty regarding which species are truly biologically distinct. Some authors suggest that the genus only contains as few as 3 to 6 species, while others place up to 50 species in the genus. Mushroom hunters refer to them by their color (e.g., gray, yellow, black) as the species are very similar in appearance and vary considerably within species and age of individual. The best known morels are the "yellow morel" or "common morel" (M. esculenta); the "white morel" (M. deliciosa); and the "black morel" (M. elata). Other species of true morels include M. conica, M. vulgaris, and the half-free morel (M. semilibera).
Early phylogenetic analyses supported the hypothesis that the genus comprises only a few species with considerable phenotypic variation. More recent DNA work has suggested more than a dozen distinct groups of morels in North America. An extensive DNA study showed three discrete clades, or genetic groups, consisting of Morchella rufobrunnea, the yellow morels (M. esculenta and others), and the black morels (M. elata and others). Within the yellow and black clades, there are dozens of individual species, most endemic to individual continents or regions. This species-rich view is supported by studies in Western Europe, Turkey, Israel, and the Himalayas.
Morchella tomentosa, a fire-associated species described from western North America, commonly known as the "gray morel", may also deserve its own clade based on DNA evidence. M. tomentosa is easily identified by its post-fire occurrence, fine hairs on the surface of young fruiting bodies, and unique sclerotia-like underground parts.
- Morchella anatolica
- Morchella angusticeps
- Morchella australiana
- Morchella bicostata
- Morchella brunnea
- Morchella capitata
- Morchella conica
- Morchella crassipes
- Morchella cryptica
- Morchella deliciosa
- Morchella deqinensis
- Morchella diminutiva
- Morchella elata
- Morchella esculenta
- Morchella esculentoides
- Morchella frustrata
- Morchella gigas
- Morchella guatemalensis
- Morchella hotsonii
- Morchella importuna
- Morchella meiliensis
- Morchella populiphila
- Morchella prava
- Morchella punctipes
- Morchella rufobrunnea
- Morchella semilibera
- Morchella septentrionalis
- Morchella septimelata
- Morchella sextelata
- Morchella snyderi
- Morchella spongiola
- Morchella tomentosa
- Morchella umbrina
- Morchella virginiana
- Morchella vulgaris
Habitat and ecology
Habitats favorable to fruition
Morchella species appear to have either symbiotic mycorrhizal relationships or act as saprotrophs. Yellow morels (Morchella esculenta) are more commonly found under deciduous trees rather than conifers, and black morels (Morchella elata) can be found in deciduous forests, oak and poplar. Deciduous trees commonly associated with morels in the northern hemisphere include ash, sycamore, tulip tree, dead and dying elms, cottonwoods and old apple trees (remnants of orchards). The fruiting of yellow morels in Missouri, USA, was found to correlate with warm weather, precipitation, and tree species, and most usually in the springtime. Morels are rarely found in the vicinity of most common poisonous mushrooms such as the sulphur tuft and fly agaric (April–May time frame), but can occur alongside "false morels" (Gyromitra sp.) and "elfin saddles" (Verpa sp.)
Association with wildfire
All types of morels may grow abundantly in forests which have been burned by a forest fire, with black morels at the start of the season, followed by the yellows, greys and greens. The mechanism for this behavior is not well known, but appears to be related to both the death of trees and the removal of organic material on the forest floor. Moderate-intensity fires are reported to produce higher abundances of morels than low or high intensities. Where fire suppression is practiced morels often grow in small amounts in the same spot year after year. If these areas are overrun by wildfire they often produce a bumper crop of black morels the following spring. Commercial pickers and buyers in North America target recently burned areas for this reason. The Finnish name, huhtasieni, refers to huhta, area cleared for agriculture by the slash and burn method. These spots may be jealously guarded by mushroom pickers, as the mushrooms are a delicacy and sometimes a cash crop.
Efforts to grow morels are rarely successful and the commercial morel industry is based on harvest of wild mushrooms.
When gathering morels, care must be taken to distinguish them from the poisonous false morels, including Gyromitra esculenta, Verpa bohemica, and others. Although the false morels are sometimes eaten without ill effect, they can cause severe gastrointestinal upset and loss of muscular coordination (including cardiac muscle) if eaten in large quantities or over several days in a row. They contain a gyromitrin-like toxin (an organic, carcinogenic poison) that is produced by the mushroom.
The key differentiating features of false morels in comparison to morels include:
- The false morels can be told apart from the true morels by careful study of the cap, which is often "wrinkled" or "brainy", rather than honeycomb or net-like. Gyromitra esculenta has a cap that is generally darker and larger than the true morels (Morchella sp.).
- The caps of early morels (Verpa sp.) are attached only at the apex (top) of the cap, unlike true morels which have caps that are attached at or near the bottom. The easiest way to tell the false from the true variety, is to simply look inside the stem.
- False morels contain a cotton-ball looking substance inside their stem while true morels are hollow inside.
- The caps of the false morel can be easily twisted in comparison to the normal morel.
- False morels are often a brown, reddish color.
Morels are a feature of many cuisines, including Provençal. Their unique flavor is prized by cooks worldwide, with recipes and preparation methods designed to highlight and preserve it. As with most edible fungi, they are best when collected or bought fresh. Morels occasionally contain insect larvae that drop out during the drying process.
One of the best and simplest ways to enjoy morels is by gently sauteeing them in butter, cracking pepper on top and sprinkling with salt. Others soak the mushrooms in an egg batter and lightly bread them with saltine crackers or flour before frying them. Lastly, morel mushrooms go great with meat or in a soup.
Morels are not improved by extensive washing or soaking, as it may ruin the delicate flavor and require long cooking times. Due to their natural porosity, morels may contain trace amounts of soil which cannot be washed out. They can best be 'flash frozen' by simply running under cold water or putting them in a bucket to soak for a few minutes, then placing on a cookie sheet or pizza pan and placing into a freezer. After freezing they keep very fresh with the frozen glaze for a long time in airtight plastic containers. However, when thawed they can sometimes turn slightly mushy in the cap. Any visible soil should be removed with a brush, after cutting the body in half lengthwise if needed.
Drying is a popular and effective method of long-term storage for morels, and they are readily available commercially in this form; dried morels can be reconstituted by soaking in warm water or milk. They may also be frozen after steaming or frying. Canning is not recommended because the necessary high pressure and temperature destroys much of the nutty flavor.
Morels contain small amounts of hydrazine toxins that are removed by thorough cooking; morel mushrooms should never be eaten raw. It has been reported that even cooked morels can sometimes cause mild intoxication symptoms when consumed with alcohol.
When eating this mushroom for the first time it is wise to consume a small amount to minimize any allergic reaction. Morels for consumption must be clean and free of decay.
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