Common Name: Yellow Morel, Common Morel, Molly Moocher, Sponge Mushroom, Honeycomb Morel, Haystack, Blond Morel, Dryland Fish, Thick-Footed Morel

Scientific Name: Morchella esculenta (An esculent is something fit for food, especially a vegetable, from the Latin esculentus)


Morels are probably the most celebrated of edible mushrooms in North America.  They were among the first to be classified as belonging to a genetic group, owing to their unique taxonomy.  The etymology of the genus name Morchella is accordingly of uncertain origin, as it first appeared in the scientific literature in 1719 and is of Swedish origin (Carolus Linnaeus 1707-1178, the father of binomial classification, was Swedish).  Theories as to the derivation of Morchella include an old German name for morel and the genus of the mulberry tree Morus due to the resemblance of the morel to the mulberry fruit.  Many European languages share similar names for the English morel such as the Bulgarian morchella, the Danish morkel, the French motile and the German morchel.


As morels are choice edibles, they are sought out by mushroom foragers throughout the world. Though they are toxic when raw, when cooked they impart an epicurean flavor reminiscent of hazelnuts to a host of gourmet dishes.  They contain more protein than most vegetables, are rich in vitamins E, D, K and the B group, and their fiber is conducive to proper intestinal function.   However, finding morels is quite challenging, as the habitat that is likely to favor their growth is imprecise and inconsistent.  They may be found under tulip poplars, white and green ash, hickory, elm, striped maple, sycamore, in abandoned apple orchards, and, most significantly, in burned areas after a fire. In some parts of Europe, laws were passed to prevent the burning of forests that had previously been set to promote morel growth the following year.  The lack of consistency in morel fruiting has been a deterrent to commercial cultivation.


The reason for the seemingly arbitrary growth of morels is the sclerotium.  When morel spores germinate, they form the underground fungal body called the mycelium, as do other fungi.  The difference is that the morel mycelium subsequently forms the sclerotium, a mass of large cells several inches in diameter resembling a slippery walnut. It is this structure that allows the fungus to survive adverse conditions for decades.  Although there have been scattered reports of successful morel production since 1883, it was not until 1982 that Ronald Ower of San Francisco succeeded in demonstrating a consistent process.  U.S. Patent number 4,594,809 was issued in 1986 specifying the series of operations necessary and sufficient  for morel cultivation. 


The unusual appearance of the morel is due to the nature of its spore production.  Most mushrooms have an umbrella-like canopy to protect the spores from moisture so that they are dry enough to be carried away by the wind to propagate. These capped mushrooms are called basidiomycetes because the spores are attached to structures called basidia that project outward from the gills.  The morel is an ascomycete, its spores are contained is sac-like sausage shaped containers called asci that project outward from the outward surface of the cap. The morel has ridges and pits that create the characteristic spongy appearance in order to provide maximum surface area for asci attachment and spore dispersal. Even with the extensive structure for spreading spores, the morel is far from efficient.  The cap does not protect the spores from getting washed away by rain and the aerodynamics of the ridge structure does not contribute appreciably to wind dispersal.


The complexity and variation of the shape of the ridged and furrowed cap of the morel is due to the process by which the spores are propelled out of the asci.  The force that acts to expel the spores is generated by the shrinkage of the tissues when they dry. If the tissue dries too fast, there will not be enough time for the spores to develop.  If the tissue dries too slowly, the morel will deliquesce (melt away) and destroy the flesh before any spores can be emitted. Accordingly, a morel cap may be composed of thick ridges for dry climates and thin ridges for wet climates, adapting to the environment as needed to promote spore dispersal.


One theory for the singular nature of the morel is that it is a recent evolutionary mutation of a yeast fungus that will ultimately devolve into a cup fungus.  Yeasts evolved some 50 million years ago in consonance with the production of sugary substances by flowering plants. In the competition against mold and bacteria for the sugar, yeasts mutated to achieve rapid growth at the expense of complexity, achieving mass doubling in about 90 minutes at standard temperature as compared to 45 minutes for bacteria. As a second competitive adaptation, yeasts break down the sugar into carbon compounds, with excreted byproducts of acid and alcohol.  These products inhibit the growth of the mold and bacteria competition.  There is some experimental evidence that morels excrete acids which attack the bacteria in the soil, which the morel then feeds on for nutrition.

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