Morchella

Morel
A black morel in Poland
Scientific classification
Kingdom:	Fungi
Division:	Ascomycota
Class:	Pezizomycetes
Order:	Pezizales
Family:	Morchellaceae
Genus:	Morchella Dill. ex Pers. (1794)
Type species
Morchella esculenta (L.) Pers. (1801)
Species
~50 worldwide (see text)
Synonyms[1]
Phalloboletus Adans. (1763) Boletus Tourn. ex Adans. (1763) Eromitra Lév. (1846) Mitrophora Lév. (1846) Morilla Quél. (1886) Morchella sect. Mitrophorae (Lév.) S.Imai (1932)

Morchella, the true morels, is a genus of edible mushrooms closely related to anatomically simpler cup fungi. These distinctive fungi appear honeycomb-like, with their cap composed of a network of ridges with pits. Morels are sought by thousands of enthusiasts every spring for their supreme taste and the joy of the hunt, and are highly prized by gourmet cooks, particularly in French cuisine.

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 or muggins. Due to the partial structural and textural similarity to some species of the Porifera sponges, a common name for any true morel is sponge mushroom.

The scientific name of the genus Morchella is derived from morchel, an old German word for mushroom, while morel itself is derived from the Latin maurus meaning brown.

Classification

Taxonomy

The fruit bodies of Morchella are highly polymorphic, varying in shape, color and size, while in many cases, they do not exhibit clear-cut dichotomous features microscopically; this has contributed to uncertainties regarding taxonomy.^[2] Discriminating between the various species is further complicated by uncertainty regarding which species are truly biologically distinct. Some authors have suggested that the genus only contains as few as 3 to 6 species,^[3][4][5] while others recognise up to 50.^[6][7][8] Mushroom hunters mostly refer to them by their color (e.g., gray, yellow, black) as the species are very similar in appearance and can vary considerably within species and age of individual. The genus is currently undergoing extensive reevaluation with regards to the taxonomical status of many species.

Phylogeny

Early phylogenetic analyses supported the hypothesis that the genus comprises only a few species with considerable phenotypic variation.^[9][10] More recent DNA work, however, has revealed more than a dozen genealogically distinct species in North America and more from Europe.^[11] An extensive DNA study revealed three discrete clades, or genetic groups, consisting of the white morels (Morchella rufobrunnea, Morchella anatolica), 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.^[12] This species-rich view is supported by studies in Western Europe,^[13] Turkey,^[14] Israel,^[15] and the Himalayas.^[16]

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.^[17][18][19]

Species

A number of species have been described in the past, many of which have been recently redefined, while others have been shown to be synonyms or illegitimate. A study by Clowez and colleagues, described over 20 new species in 2012.^[20] In the same year, another study by Kuo et al. described 19 phylogenetic species from North America,^[21] while molecular phylogenetics currently suggest there are more than 60 species of Morchella worldwide.^[22] A further revision of the taxonomy of the genus provided by Richard et al. in 2014, applied names to 30 of the genealogical lineages recognized so far.^[23] Also in 2014, Clowez et al. described Morchella fluvialis from riparian forests in Spain.^[24] In 2015, Loizides et al. clarified the taxonomy of Morchella tridentina, a cosmopolitan species described under many names, and recombined Morchella kakiicolor as a distinct species.^[25]

Habitat and ecology

Yellow morels in West Virginia, USA

The ecology of Morchella species is not fully understood. Many species appear to form symbiotic or endophytic relationships with trees,^{[27][28][29][30]} while others appear to act as saprotrophs.^[17][31] Yellow morels (Morchella esculenta and related species) are more commonly found under deciduous trees rather than conifers, while black morels (Morchella elata and related species) are mostly found in coniferous forests, disturbed ground and recently burned areas.^[32][33] Morchella galilaea,^[34] and occasionally Morchella rufobrunnea,^[35] appear to fruit in the autumn or winter months rather than spring, which is the typical fruiting season for morels.

The reported host trees of Morchella species vary greatly depending on the continent or region. In western North America morels are often found in coniferous forests, including species of Pinus, Abies, Larix, and Pseudotsuga, as well as in cottonwood riparian forests.^[36] 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. In the UK, they appear during May and June. Morels are rarely found in the vicinity of most common poisonous mushrooms such as the sulphur tuft and fly agaric (April–May time frame),^[37] but can occur alongside "false morels" (Gyromitra spp.) and "elfin saddles" (Verpa spp.)

Black morels are known to be consumed by grizzly bears (species Ursus arctos horribilis) in Yellowstone National Park.^[38]

Association with wildfire

Longneck morel in Indiana, USA

Certain Morchella species exhibit a pyrophilic behaviour and may grow abundantly in forests which have been recently burned by a forest fire.^[39] The mechanism for this behavior is not well known,^[17] but appears to be related to both the death of trees and the removal of organic material on the forest floor.^[40] Moderate-intensity fires are reported to produce higher abundances of morels than low or high intensities.^[19] 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 closely guarded by mushroom pickers, as the mushrooms are a delicacy and sometimes a cash crop.^[36]

Efforts to grow morels are rarely successful and the commercial morel industry is based on harvest of wild mushrooms.^[36]

False morels

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, for some people, 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:^[41]

• 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.

Gastronomical value

Yellow morels in France

Morels are a feature of many cuisines, including Provençal.^[42] 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. 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. They are great additions to meat dishes or soups. However, as morels are known to contain thermolabile toxins, they must always be cooked before eating.

Black morels in British Columbia, Canada

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, so they are best frozen after steaming or frying.^[43] 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. Any insect larvae which might be present in the fruit bodies drops out during the drying process.^[44]

Toxicity

Morels contain small amounts of hydrazine^[45] toxins that are removed by thorough cooking; morel mushrooms should never be eaten raw.^[46] It has been reported that even cooked morels can sometimes cause mild symptoms of upset stomach when consumed with alcohol.^[47]

When eating this mushroom for the first time it is wise to consume a small amount to minimize any allergic reaction. As with all fungi, morels for consumption must be clean and free of decay. Morels growing in old apple orchards that had been treated with the insecticide lead arsenate may accumulate levels of toxic lead and arsenic that are unsuitable for human consumption.^[48]

See also

• Truffle

References

External links

Wikimedia Commons has media related to Morchella.

• Morchella in Index Fungorum
• MushroomExpert.com's Morel section
• A Beginner's Guide to Hunting Morel Mushrooms, from Field and Stream

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