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I understand that truffles share a symbiotic relationship as they reside among the root systems of host trees, but I cannot find any material that specifies the details of such a relationship. In other words, what exactly do truffles get from their host trees, and what do they provide in turn?
A truffle is the fruiting body of a subterranean Ascomycete fungus, predominantly one of the many species of the genus Tuber. Truffles are ectomycorrhizal fungi and form symbiotic relationships with the roots of several tree species including beech, birch, hazel, hornbeam, oak, pine, and poplar.
Mycorrhizal symbiosis is a mutualistic association between a fungus and the roots of a plant (usually a tree) in which (typically) the fungus obtains energy in the form of carbohydrates from the plant, and the plant gains the benefits of the mycelium's higher absorptive capacity for water and mineral nutrients, partly because of the large surface area of fungal hyphae, which are much longer and finer than plant root hairs, and partly because some such fungi can mobilize soil minerals unavailable to the plants' roots. The effect is thus to improve the plant's mineral absorption capabilities.
Based on the quote below from the website of a truffle nursery in Australia (http://trufficulture.com.au/what_are_truffles.html), it sounds like truffle symbiosis is a completely standard mycorrhizal symbiotic relationship.
The truffle coats the tips of the tree roots to form mycorrhiza which act as an extension of the tree's root system. The tree provides the truffle with a source of photosynthesised carbohydrates, and in return the fine, thread-like filaments (mycelia) of the truffle, extract and trade soil minerals and nutrients which would normally be unavailable to the tree. Thus the mycorrhiza is able to increase the effectiveness of the trees roots, enabling the tree to grow in soils which would normally be too nutrient deficient to support them.
Truffles: everything you need to know
A truffle is a fungal fruiting body that develops underground. It relies on mycophagy for spore dispersal. Almost all truffles are usually found in close proximity with trees. There are hundreds of species of truffles, but the genus Tuber specie is the most highly prized as foodstuff. Edible truffles are held in high esteem in French and northern Italian cooking, as well as in the international haute cuisine.
The mycelia of truffles form symbiotic relationships with the roots of several tree species, including beech, poplar, oak, birch, hornbeam, hazel, and pine. They prefer argillaceous or calcareous soils which are well drained and neutral or alkaline. Truffles fruit throughout the year, depending on the species, and can be found buried between leaf litter and soil.
The origin of the word truffle appears to be the Latin word tuber, meaning "lump", which later became tufer and gave rise to the various European terms: French truffe, Spanish trufa, German Trüffel, Dutch truffel and in piedmontese "Le Trifole". In Portuguese, the words trufa and túbera are synonyms — the latter closer to the Latin term. The German word Kartoffel ("potato") is derived from the Italian tartufo (truffle) due to superficial similarities.
Over several years, the Peay lab has gathered about 1,500 soil samples from 68 pine forests, which represent a swath of North America from Florida to Alaska. In past work, they sequenced DNA in each sample to understand what fungal species live in that soil, and in what abundance. Their results, published previously, suggested that fungi were different in each region, contradicting a common assumption that those communities would look similar in most places in the world. They followed that up by mapping the associations between trees and symbiotic microbes around the world.
Mapping microbial symbioses in forests
Data collected from over 1 million forest plots reveals patterns of where plant roots form symbiotic relationships with fungi and bacteria.
For their latest paper, Brian Steidinger, a postdoctoral scholar in the Peay lab, explored the relationship between these geographical fungal patterns and historical climate data.
“We took soil from the cores and climatic data unique to each site,” said Steidinger, who was lead author of the study. “We found that climate was by far the most important predictor of contemporary fungal diversity patterns across North America.”
Steidinger also found that different regions of North America had unique optimal temperatures for fungal diversity. For example, cold boreal forests had a diversity peak around 5 C mean annual temperature, while Eastern temperate forests peaked in diversity near 20 C.
The researchers then applied these data to predict future diversity, given projections of climate change produced by the Intergovernmental Panel on Climate Change. Because of the regional differences in optimal climate for fungal diversity, some forests, particularly those in the North and Northwest, could experience major decreases in fungal diversity.
“According to our models, climate change over the next 50 years could eliminate more than a quarter of ectomycorrhizal species inside 3.5 million square kilometers of North American pine forests,” said Steidinger. “That’s an area twice the size of Alaska.”
Other regions, such as the Eastern temperate forests, could experience gains of 30 to 50 percent – assuming it is as easy to develop new species as to lose them.
“One of the things that’s kind of shocking and a little bit scary is that we predict there will be some pretty significant decreases in diversity in western North America, well known culturally for fungal diversity and for people who are interested in collecting edible mushrooms,” Peay said.
Symbiotic relationship between California oaks and mutualist fungi appears to provide a buffer for climate change
Mutualist root fungi extend the reach of plants and trees to nutrients in faraway places. Credit: Wikimedia Commons
"Happy families are all alike each unhappy family is unhappy in its own way." So goes the first line of Leo Tolstoy's "Anna Karenina." Little did the Russian novelist know his famous opening line would one day be used to describe microbial communities, their health and their relationships to their hosts.
It's this idea that an unhealthy or stressed host to a microbiome has a more diverse microbiome than its healthy counterpart," said UC Santa Barbara ecologist An Bui, a graduate student researcher in the lab of theoretical ecologist Holly Moeller. The diversity, she said, is a response to variable conditions that may in turn indicate an unstable or stressed environment. "Healthy hosts are probably going to have very similar microbiomes," she said, "while unhealthy hosts are different in their own ways."
Bui and colleagues recently put the Anna Karenina hypothesis to the test in California's Tehachapi mountains as they sought to understand how climate change might affect fungal communities in woodland soil in a future California.
"Fungi are really important for woodland systems," said Bui, the lead author of a study that appears in the journal FEMS Microbiology Ecology. "But we don't necessarily know how they will change with climate change."
As the global average temperature rises, forests and woodlands around the world are under increasing threat, she explained.
"It's not just about temperature and rainfall, but also the organisms the trees and plants associate with," she said. Soil fungi have a variety of relationships with woodland plants. Saprotrophic fungi, for instance, decompose dead organic matter, while pathotrophs eat live organic matter.
And then there are the symbiotrophs, which engage in mutually beneficial relationships with their plant hosts via their roots. Attaching to roots and extending threadlike hyphae in every direction underground—the so-called "Wood Wide Web"—mycorrhizae give the woodland tree and plant community access to nutrients from faraway places.
"They get all of their energy in an exchange for carbon from trees and other plants," Bui said. "And then they give their hosts nitrogen and phosphorus from the soil." These fungi provide almost half of a tree's organic nitrogen budget, according to the study, and contribute the bulk of new carbon into the soil.
To get a sense of how warming could affect California's woodland soil fungal community, the team sampled soils at sites along an arid (dry) to mesic (moderately moist) climactic gradient at the Tejon Ranch in the Tehachapi mountains.
"The sites we worked at were a proxy for what we think California would look like with future climate change," Bui said. As one ascends from the warmer, drier base of the mountains into the cooler, moister elevations, the landscape changes with the temperature and relative humidity, giving the researchers a glimpse of what California woodlands might look like as climate change forces them to retract.
Of particular interest to the team were the soils around the oak trees that dot the landscape, where, in addition to the decomposers and pathogenic fungi in the soil, tree-mutualist mycorrhizae create their vast networks. The researchers were interested in how the number of species and their abundance might change between sites.
"As it turns out, the fungal communities are completely different," Bui said. "And the hottest, driest sites have the highest number and the greatest diversity in fungal species." True to the Anna Karenina hypothesis, the trees under the more arid, stressful conditions had the most diverse and dispersed fungal communities.
But, while the larger fungal communities varied from site to site, Bui said, the communities of mutualists within them tended to remain the same, save for small shifts within the mutualist populations to select for traits that could be more useful under the the circumstances.
"When we looked at ectomycorrhizae and arbuscular mycorrhizae, those communities were more similar across climactic conditions than the whole fungal community," she said. "So there's a possibility that host association for mutualists at least buffers that shift in community structure the whole fungal community experiences."
If so, the benefit could be reciprocal, according to the researchers. Buffering the fungi from climate change preserves their function, which could, in turn, conserve their host trees' function in the face of a changing California woodland ecosystem.
More work would need to be done to understand how far this buffering effect would extend, but the results are a positive bit of news for the future of California woodlands. Further studies could broaden the scope to include how these relationships and other adaptations might affect tree health, according to Bui.
"I think this gives us a little bit of hope that the players in this ecosystem that are crucial for the survival of the habitat for many species—like the oaks—might be able to keep doing what they're doing," she said. "Even though we do need to do a lot of work in terms of conservation and mitigation, there's a possibility for them to persist. And I think that's hopeful and exciting."
How Truffles Grow
Once you decide you want to start growing truffles, you will need to know as much about the process as possible. Use this information to prepare for the tough road ahead and ensure that you don’t make costly beginner mistakes.
One important thing to keep in mind is that the way truffles grow is unusual compared with other things. They actually have a symbiotic relationship with oak or filbert trees.
The truffles grow on the roots of trees underground and use the tree as their main source of nutrients. Then, once the truffles are fully-grown, the trees feed off of them.
This relationship is a give-and-take that benefits both sides, but the truffles should be harvested before the trees begin to feed off of them.
The trees lay dormant when the winter months come or when temperatures start to drop. This allows the truffles to use the tree’s nutrients to stay alive and growing.
Dogs can help find truffles you grow
Harvesting Fully Grown Truffles
When you have successfully grown your truffles, one part of the process requires you to have a four-legged helper.
Since truffles grow underground, there is no way for humans to know where all the truffles are, so you might end up digging everywhere. You might also not be able to harvest all the full-grown truffles underground.
As such, training a dog to recognize the truffle scent will allow it to lead you to each one of the ready-to-harvest truffles. With the dog’s keen sense of smell, they can sniff out the truffles and alert you, so you know where to dig.
This process can take some time if you are on your own with a single dog. But if you have a few helpers for harvest, each with a dog of their own, the process can go by quicker.
Therefore, if you are attempting to grow some truffles on your own, taking time to train your dog or adopt one to train will be a great way to prepare for the harvest while the truffles are still growing.
The training can take some time, so being prepared early on will give your dog time to get used to it.
What Dog Breeds Are the Best for the Job?
The good news is any dog that has a good sense of smell and likes food rewards can get the job done. This pretty much describes almost all dogs, so you will likely have little trouble finding one that will not do it.
As mentioned, just start the training early for the dog or dogs to get good at it before the actual harvest. With that in mind, although most dogs can do the job, it is probably a good idea to get a large dog.
That is because it could get tiring to complete a whole harvest for a smaller dog. A larger dog that is more athletic will likely do better without getting tired or fatigued during the process.
Likewise, larger dogs often eat more, which means they love food rewards and will be more motivated to be trained and accomplish the task.
Take some treats with you to reward your dog with, and you will have a professional truffle-sniffer for many harvests to come!
Chipmunks and Truffles - A Recipe for a Healthy Forest
A gluttonous eastern chipmunk. Photo by Brian Lasenby.
While on an afternoon hike last fall, I sat down at the base of a large tree to take in what might be going unnoticed. Within seconds, a chipmunk appeared from behind a pile of large rocks. Based on its behavior, I suspected this chipmunk had had the good fortune of a past encounter with a hiker willing to share a snack. When it realized that I had nothing to offer, the chipmunk turned and began searching the area. It quickly stopped and began digging. Lucky guy, I thought, assuming that the chipmunk had located a cached acorn buried by a hard-working gray squirrel. It came as a surprise, then, when in less than a minute, the chipmunk unearthed an acorn-sized truffle!
Most of us have heard of truffles, though we often associate them with fancy European restaurants black and white truffles, in particular, are prized ingredients. But truffles exist here, as well, and while our Northeastern chipmunks probably don&rsquot have gourmet tastes, they&rsquore certainly gourmand in their taste for truffles.
Small-mammal gnawing marks on a deer truffle. Photo by Ryan Stephens.
A wide variety of fungi are found in most forests, and loosely speaking, they obtain nutrients in one of three ways. Saprotrophic fungi are decomposers. They release acids and enzymes that break down dead tissue into smaller molecules that they can absorb. Decaying wood, plants, and even some animals can become food for a saprotroph. Examples of these include oyster and shiitaki mushrooms. Parasitic fungi infect a living host and sometimes kill it. The distinction between parasitic and saprotrophic fungi isn&rsquot always clear for example, some bracket fungi that produce conks on the exterior of a tree trunk can be both. Mycorrhizal fungi form symbiotic relationships with the root systems of forest plants. Common examples include porcini, chanterelle mushrooms, and almost all truffles.
The fungal &ldquomycelium&rdquo &ndash a mass of branching, thread-like fibers &ndash encapsulate the roots of a tree and extend out into the soil where they capture water, nitrogen, phosphorus, and other nutrients that are then transported to the tree&rsquos roots. In return, the mycelium fibers obtain carbohydrates (sugars) from the roots. A number of field and laboratory experiments have demonstrated that removing the fungus substantially reduces the growth rate of a tree and can result in its death. So, healthy trees need their fungi and fungi need their trees.
University of New Hampshire researchers inventory truffles in the White Mountain National Forest. Photo by John A. Litvaitis.
The term &ldquotruffle&rdquo is commonly used in reference to the belowground fruiting body, or sporocarp, that enables reproduction. An above-ground mushroom&rsquos fruiting body grows up and out of the ground on a stem and then develops a cap that contains spores. Once the cap dries out, it releases the spores into the wind as a means of reproduction. But because truffles fruit in the soil, this wind-blown spore dispersal mechanism isn&rsquot possible. The truffles&rsquo cap has evolved into an underground mass that resembles a small potato within that mass are millions of spores and each can develop into a new truffle-bearing fungus. So, how do truffle spores disperse if they are below ground?
It&rsquos important to be eaten
Let&rsquos return to the chipmunk I encountered on my hike. As it handled what seemed to be a stag or deer truffle (genus Elaphomyces), the chipmunk seemed most intent on eating the outer rind, or peridium. No doubt it also swallowed a number of spores found inside. In addition to chipmunks, flying squirrels, red squirrels, various voles and mice, deer, bears, and even fishers are known to consume truffles. Truffles provide these animals with nutrients, essential minerals, amino acids, and vitamins. Vitamin D in some truffles occurs in higher concentrations than most other foods available in the forest, and for nocturnal rodents, truffles may be an important source of this &ldquosunshine vitamin.&rdquo
In New Brunswick, Canada, red squirrels and northern flying squirrels are major truffle consumers. Truffle researcher Karl Vernes found that red squirrels cache truffles as they do spruce cones, often in a central location or midden. Near the town of Moncton, for example, a suburban red squirrel was found to be using an abandoned robin&rsquos nest to store more than 50 deer truffles. Truffles preserve well simply by air drying, so having a cupboard well stocked with truffles is a wise strategy for a snowbound squirrel.
Similar to berry-eating birds, chipmunks and other animals that eat truffles disperse the undigested spores, helping to establish new populations of the fungus. Additionally, researchers found that fungal spores collected from flying squirrel droppings had a higher germination rate than spores collected directly from the truffle. This suggests that, in addition to aiding in spore dispersal, the success of spores may be enhanced by passing through the digestive tract where they are exposed to body heat and digestive enzymes. Or it may simply be that fungal spores deposited in droppings have a readily available supply of fertilizer.
The relationships among trees, truffles, and small mammals illustrate the inter-connectedness of organisms in this ecosystem.
How do animals locate a buried truffle? Above-ground fruits signal to animals that they are ready to be eaten by changing color truffles also signal to their consumers, but do it with a distinct odor. As truffles mature, they produce strong, chemically complex odors that attract many small mammals. The scent of a truffle may contain compounds similar to certain animal pheromones, meaning that a little goes a long way. And like pheromones, they are often species-specific. The truffles I&rsquove handled range from mildly foul, like something rotting, to a very pleasant citrus-like odor. Responding to these olfactory cues, small mammals are adept at uncovering mature fruit-bodies of truffle fungi. This clue to finding truffles has also been used by human foragers seeking prized white and black truffles in southern Europe. Historically, human- truffle-hunters relied on the sensitive snout of a domestic pig that was tethered on a leash. Pigs are efficient in rooting out truffles however, a major downside to this approach is that they often eat the truffles before their handler can scoop them up. As a result, dogs have replaced pigs because they are more interested in a treat as a reward than eating the truffles they sniff out.
How widespread is the truffle connection?
In their comprehensive book Trees, Truffles, and Beasts &ndash How Forests Function, authors Chris Maser, Andrew Claridge, and James Trappe summarize decades of their research on truffles in the Pacific Northwest and Australia. They trace the long evolutionary history of truffles and show that the relationships among trees, fungus, and fungus-eating (mycophagous) animals have existed for a very long time and likely occur throughout the forests of the world.
The abundance of truffles, especially in softwood or conifer stands, provides a reliable food source for many animals. Photo by Ryan Stephens.
In northern Minnesota, forest ecologists John Terwilliger and John Pastor were puzzled as to why black spruce trees were rare in abandoned, drained beaver meadows, yet very common in surrounding forests. Using information on the diet and distribution patterns of red-backed voles, a major consumer of truffles in that region, these researchers were able to demonstrate that it was the reluctance of voles to enter the meadows and the lack of their spore-filled droppings that limited black spruce from colonizing the meadows. Fungal spores and the mycorrhizal network that eventually develops are essential for seedling spruces to thrive.
In New England, the role of truffles in forest ecosystems had largely gone unexamined until researchers from the University of New Hampshire recently took on the topic. Associate Professor Rebecca Rowe and doctoral student Ryan Stephens are leading the investigation in the White Mountain National Forest. Among the questions they are addressing: What conditions affect the distribution and abundance of truffles in northern forests?
Although fundamental to our knowledge of forest ecology, such information can also aid in understanding how disturbances, natural or human-caused, can affect mycorrhizal fungi, thereby aiding in the development of approaches that might help offset such disruptions to this co-dependent system. To answer this question, Stephens and Rowe inventoried the abundance and variety of truffles in different parts of the forest, divided by dominant tree groupings. Hardwood stands included American beech, red maple, sugar maple, yellow birch, white birch, and white ash. Softwood stands were dominated by eastern hemlock, red spruce, balsam fir, and an occasional white pine. Finally, mixed-wood stands included a combination of both hardwoods and softwoods. Within each forest type, Stephens and his field assistants used garden cultivators to rake up samples of the forest floor and then carefully filtered through the rotting leaves, needles, branches, and soil in search of truffles.
In the White Mountains of New Hampshire, mature stands of eastern hemlock provide the greatest abundance of truffles. This raises some concern with the potential decline of hemlocks with the spread of wooly adelgids across the Northeast. Photo by John A. Litvaitis.
Suspecting that this method might miss some truffles, Stephens also used chipmunks as an additional source of information. Small, baited box traps were set to capture chipmunks in the same forest stands that were sampled by digging. When captured, small mammals usually defecate in the trap. So it&rsquos quite easy to get several samples from an animal and then release it. The more challenging part of this approach is identifying the specific truffles eaten by chipmunks from the fungal spores found in their droppings. Size and shape of spores are often unique for a variety of truffle, and there are standardized keys that lead a biologist to a correct identification. But spores are quite small &ndash some just a fraction of the width of a human hair &ndash and as a result, extreme care and the use of a powerful microscope is required when preparing and identifying samples.
While the research is not yet complete, Stephens and his colleagues have found some interesting patterns. Truffles were most abundant in softwood stands, with an average of roughly 60 pounds growing per acre, and least abundant in hardwoods, with less than 7 pounds per acre. Not surprisingly, chipmunk droppings yielded a greater variety of truffles than the researchers were able to locate on their own. Chipmunks are capable of finding truffles that are no larger than a plump grain of rice.
Among individual trees, eastern hemlocks were consistently associated with sites containing the most truffles. Even in hardwood stands, clusters of truffles were located at the base of a lone hemlock. This pattern suggests a tight relationship between hemlocks and several of the most common truffles that Stephens found in the White Mountains. That relationship makes sense because hemlocks are abundant in northern forests and they are among the longest-lived trees, which must be an attractive trait to a symbiotic fungi.
Deer truffles are among the most common variety found in northern forests. Photo by Ryan Stephens.
The human connection
The researchers also found that the vitality of truffle-producing fungi is clearly linked to its host trees. When trees are removed or the composition of a forest changes over time, the diversity and abundance of truffles in the forest will also change. As a result, wildfires and timber harvests can have a large effect on truffles. Removal of host trees eliminates the supply of energy to the fungus and that prevents it from producing truffles. In addition to removing host trees, soil temperature, moisture content, and compaction can limit truffles. Based on that information, foresters and loggers might be encouraged to leave small groups of trees that include at least one dominant tree to ensure that important fungi remain on a site where most trees are removed. In northern New England, it may be especially appropriate to leave groups of hemlock.
The association of truffles with eastern hemlocks raises greater concerns because of the recent invasion into the Northeast of the hemlock woolly adelgid, an insect that threatens the hemlock&rsquos very existence. At the Harvard Forest in western Massachusetts, forest ecologists are attempting to understand the changes that will occur to forest composition if hemlocks die out. Using experimental removals (where hemlocks are cut) and computer simulations, they predict that white pine, black birch, and beech trees may become more abundant. Their results also indicate that changes in forest composition will vary with local conditions, such as soil fertility and rainfall patterns. Regardless of which species replace them, there&rsquos no doubt that with a loss of hemlocks, the diversity and perhaps abundance of truffles will change.
Understanding the role of small mammals and truffles in maintaining the vitality of our forests highlights the interdependence of organisms and how those connections may be disrupted. Chipmunks and truffles may be small, but it is quite impressive to see how important they are to a healthy forest.
John Litvaitis has worked as a wildlife ecologist for county, state, and federal natural resource agencies in New Jersey, Florida, and Oklahoma. After 31 years as a professor at the University of New Hampshire, he is “re-wiring” his career as a full-time advocate for wildlife. John lives in Madbury, New Hampshire.
© 2018 by the author this article may not be copied or reproduced without the author's consent.
Spores and dissemination
Mature deer truffles harbor a dark blue to purple spore mass inside that can be pulled apart as tough filaments.
Reynolds (2011) concludes in her dissertation on Elaphomyces that while it clearly relies on animal vectors for excavation and dispersal. However, the history of long-distance dispersal of the genus and current spore trajectories suggest that Elaphomyces spores can also be dispersed passively in the air. This is because the spores can remain airborne long enough to be dispersed over long distances by the wind.
Mycotrophic wildflowers are sometimes called "fungus flowers." There are two characteristics these plant exhibit that are similar to fungi: their mode of obtaining water, minerals and carbohydrates and, when the plant pushes up through the soil surface they have the appearance of a mushroom poking out of the ground.
There are eight genera and nine species of mycotrophic wildflowers in the Heath family (Ericaceae) native to the United States. They occur more commonly in the western United States, especially in mixed and coniferous forests.
Sweet pinesap (Monotropsis odorata) is the only species that does not occur in the western United States. It is a rare wildflower restricted to rich hardwood forests in the southeastern United States. Wildflower enthusiasts who are hiking through rich hardwood forest in North Carolina may begin to smell violets! Though there are no violets to be seen, a sharp eye may detect the camouflaged sweet pinesap.
Sweet pinesap (Monotropsis odorata). Photo by Hugh and Carol Nourse.
Snow plant (Sarcodes sanguinea). Photo by Gary Monroe.
Sugarstick (Allotropa virgata). Photo by Russ Holmes.
Several of the mycotrophic wildflowers are quite colorful and beautiful. Snow plant (Sarcodes sanguinea) is a brilliant scarlet red. Sugarstick (Allotropa virgata) is another beautiful wildflower. This common name is derived from the beautiful red and white striping on the flower stalk. Other colorful wildflowers from this group include pinedrops (Pterospora andromedea) and pinesap (Monotropa hypopitys) with their shades of pinkish-red and yellow. One of the more fascinating members of this group of mycotrophic wildflowers is the ghost plant (Monotropa uniflora). Ghost plant is a ghostly white translucent color.
Pinedrops (Pterospora andromedea). Photo by Charles Peirce.
Pinesap (Monotropa hypopitys). Photo by Nancy Cotner.
Ghost plant (Monotropa uniflora). Photo by Gary Monroe.
Fringed pinesap (Pleuricospora fimbriolata) and the gnome plant (Hemitomes congestum) are the only two mycotrophic species in the heath familiy (Ericaceae) to have a fleshy berry as a fruit. The other mycotrophic species in the heath family have a dry capsule as a fruit.
The diminutive California pinesap (Pityopus californica) barely pokes its head up through the leaf litter. The California pinesap is not commonly encountered and is easily over looked. It is the smallest mycotrophic wildflower in the heath family.
Fringed pinesap (Pleuricospora fimbriolata). Photo by Norman Jensen.
Gnome plant (Hemitomes congestum). Photo by Allyn G. Smith.
California pinesap (Pityopus californica). Photo by Barry Rice.
The first mention of truffles appears in the inscriptions of the neo-Sumerians regarding their Amorite enemy's eating habits (Third Dynasty of Ur, 20th century BC)  and later in writings of Theophrastus in the fourth century BC. In classical times, their origins were a mystery that challenged many Plutarch and others thought them to be the result of lightning, warmth, and water in the soil, while Juvenal thought thunder and rain to be instrumental in their origin. Cicero deemed them children of the earth, while Dioscorides thought they were tuberous roots. 
Rome and Thracia in the Classical period identified three kinds of truffles: Tuber melanosporum, T. magnificus, and T. magnatum. The Romans instead used a variety of fungus called terfez, also sometimes called a "desert truffle". Terfez used in Rome came from Lesbos, Carthage, and especially Libya, where the coastal climate was less dry in ancient times.  Their substance is pale, tinged with rose. Unlike truffles, terfez have little inherent flavour. The Romans used the terfez as a carrier of flavour, because the terfez tend to absorb surrounding flavours. Indeed, since Ancient Roman cuisine used many spices and flavourings, the terfez were appropriate in that context.
Middle Ages Edit
Truffles were rarely used during the Middle Ages. Truffle hunting is mentioned by Bartolomeo Platina, the papal historian, in 1481, when he recorded that the sows of Notza were without equal in hunting truffles, but they should be muzzled to prevent them from eating the prize. 
Renaissance and modernity Edit
During the Renaissance, truffles regained popularity in Europe and were honoured at the court of King Francis I of France. They were popular in Parisian markets in the 1780s, imported seasonally from truffle grounds, where peasants had long enjoyed them. Brillat-Savarin (1825) noted that they were so expensive, they appeared only at the dinner tables of great nobles and kept women. They were sometimes served with turkey.
Truffles long eluded techniques of domestication, as Jean-Anthelme Brillat-Savarin (1825) noted:
The most learned men have sought to ascertain the secret, and fancied they discovered the seed. Their promises, however, were vain, and no planting was ever followed by a harvest. This perhaps is all right, for as one of the great values of truffles is their dearness, perhaps they would be less highly esteemed if they were cheaper. 
Truffles can be cultivated.  As early as 1808, attempts to cultivate truffles, known in French as trufficulture, were successful. People had long observed that truffles were growing among the roots of certain trees, and in 1808, Joseph Talon, from Apt (département of Vaucluse) in southern France, had the idea of transplanting some seedlings that he had collected at the foot of oak trees known to host truffles in their root system.
For discovering how to cultivate truffles, some sources now give priority to Pierre II Mauléon (1744–1831) of Loudun (in western France), who began to cultivate truffles around 1790. Mauléon saw an "obvious symbiosis" between the oak tree, the rocky soil, and the truffle, and attempted to reproduce such an environment by taking acorns from trees known to have produced truffles, and sowing them in chalky soil.   His experiment was successful, with truffles being found in the soil around the newly grown oak trees years later. In 1847, Auguste Rousseau of Carpentras (in Vaucluse) planted 7 hectares (17 acres) of oak trees (again from acorns found on the soil around truffle-producing oak trees), and he subsequently obtained large harvests of truffles. He received a prize at the 1855 World's Fair in Paris. 
These successful attempts were met with enthusiasm in southern France, which possessed the sweet limestone soils and dry, hot weather that truffles need to grow. In the late 19th century, an epidemic of phylloxera destroyed many of the vineyards in southern France. Another epidemic killed most of the silkworms there, too, making the fields of mulberry trees useless. Thus, large tracts of land were set free for the cultivation of truffles. Thousands of truffle-producing trees were planted, and production reached peaks of hundreds of tonnes at the end of the 19th century. In 1890, 75,000 hectares (190,000 acres) of truffle-producing trees had been planted.
In the 20th century, with the growing industrialization of France and the subsequent rural exodus, many of these truffle fields (champs truffiers or truffières) returned to wilderness. The First World War also dealt a serious blow to the French countryside, killing 20% or more of the male working force. As a consequence, newly acquired techniques of trufficulture were lost. Between the two world wars, the truffle groves planted in the 19th century stopped being productive. (The average lifecycle of a truffle-producing tree is 30 years.) Consequently, after 1945, the production of truffles plummeted, and the prices have risen dramatically. In 1900, truffles were used by most people, and on many occasions. [ citation needed ] Today, they are a rare delicacy reserved for the rich, or used on very special occasions.
In the 1970s, new attempts for mass production of truffles were started to make up for the decline in wild truffles. About 80% of the truffles now produced in France come from specially planted truffle groves. [ citation needed ] Investments in cultivated plantations are underway in many parts of the world using controlled irrigation for regular and resilient production.   Truffle-growing areas exist in numerous countries. [ citation needed ]
A critical phase of the cultivation is the quality control of the mycorrhizal plants. Between 7 and 10 years are needed for the truffles to develop their mycorrhizal network, and only after that the host-plants come into production. A complete soil analysis to avoid contamination by other dominant fungus and a very strict control of the formation of mycorrhizae are necessary to ensure the success of a plantation. Total investment per hectare for an irrigated and barrier-sealed plantation (against wild boars) can cost up to €10,000.  Considering the level of initial investment and the maturity delay, farmers who have not taken care of both soil conditions and seedling conditions are at high risk of failure.
New Zealand and Australia Edit
The first black truffles (Tuber melanosporum) to be produced in the Southern Hemisphere were harvested in Gisborne, New Zealand, in 1993. 
New Zealand's first burgundy truffle was found in July 2012 at a Waipara truffle farm. It weighed 330 g and was found by the farm owner's beagle. 
In 1999, the first Australian truffles were harvested in Tasmania,  the result of eight years of work. Trees were inoculated with the truffle fungus in the hope of creating a local truffle industry. Their success and the value of the resulting truffles has encouraged a small industry to develop. In 2008, an estimated 600 kilograms (1,300 pounds) of truffles were removed from the rich ground of Manjimup. Each year, the company has expanded its production, moving into the colder regions of Victoria and New South Wales.
In June 2014, A grower harvested Australia's largest truffle from their property at Robertson, in the Southern Highlands of New South Wales. It was a French black perigord fungus weighing in at 1.1172 kg (2 lb 7 + 7 ⁄ 16 oz) and was valued at over $2,000 per kilogram 
United States Edit
Tom Michaels, owner of Tennessee Truffle, began producing Périgord truffles commercially in 2007.  At its peak in the 2008–2009 season, his farm produced about 200 pounds of truffles, but Eastern filbert blight almost entirely wiped out his hazel trees by 2013 and production dropped, essentially driving him out of business.  Eastern filbert blight similarly destroyed the orchards of other once promising commercial farmers such as Tom Leonard, also in East Tennessee, and Garland Truffles in North Carolina. Newer farmers such as New World Truffieres clients Pat Long in Oregon and Paul Beckman in Idaho, or  Likewise, Ian Purkayastha of Regalis Foods has set up a small farm in Fayetteville, Arkansas.  
Nancy Rosborough of Mycorrhiza Biotech in Gibsonville, North Carolina reports their 2021 harvests are outstanding, producing as much as an estimated 200 pounds of bianchetto, or “whitish” truffles on one plot. 
Other uses Edit
The Prophet Muhammad advised his Companions to use truffle to treat illnesses of the eyes. 
The origin of the word "truffle" appears to be the Latin term tūber, meaning "swelling" or "lump", which became tufer- and gave rise to the various European terms: Danish trøffel, Dutch truffel, English truffle, French truffe, German Trüffel, Greek τρούφα trúfa, Italian tartufo, Polish trufla, Romanian trufă, Spanish trufa, and Swedish tryffel.
The German word Kartoffel ("potato") is derived from the Italian term for truffle because of superficial similarities.  In Portuguese, the words trufa and túbera are synonyms, the latter closer to the Latin term.
Phylogenetic analysis has demonstrated the convergent evolution of the ectomycorrhizal trophic mode in diverse fungi. The subphylum, Pezizomycotina, containing the order Pezizales, is approximately 400 million years old.  Within the order Pezizales, subterranean fungi evolved independently at least fifteen times.  Contained within Pezizales are the families Tuberaceae, Pezizaceae, Pyronematacae, and Morchellaceae. All of these families contain lineages of subterranean or truffle fungi. 
The oldest ectomycorrhizal fossil is from the Eocene about 50 million years ago. This indicates that the soft bodies of ectomycorrhizal fungi do not easily fossilize.  Molecular clockwork has suggested the evolution of ectomycorrhizal fungi occurred approximately 130 million years ago. 
The evolution of subterranean fruiting bodies has arisen numerous times within the Ascomycota, Basidiomycota, and Glomeromycota.  For example, the genera Rhizopogon and Hysterangium of Basidiomycota both form subterranean fruiting bodies and play similar ecological roles as truffle forming ascomycetes. The ancestors of the Ascomycota genera Geopora, Tuber, and Leucangium originated in Laurasia during the Paleozoic era. 
Phylogenetic evidence suggests that the majority of subterranean fruiting bodies evolved from above-ground mushrooms. Over time mushroom stipes and caps were reduced, and caps began to enclose reproductive tissue. The dispersal of sexual spores then shifted from wind and rain to utilizing animals. 
The phylogeny and biogeography of the genus Tuber was investigated in 2008  using internal transcribed spacers (ITS) of nuclear DNA and revealed five major clades (Aestivum, Excavatum, Rufum, Melanosporum and Puberulum) this was later improved and expanded in 2010 to nine major clades using large subunits (LSU) of mitochondrial DNA. The Magnatum and Macrosporum clades were distinguished as distinct from the Aestivum clade. The Gibbosum clade was resolved as distinct from all other clades, and the Spinoreticulatum clade was separated from the Rufum clade. 
The truffle habit has evolved independently among several basidiomycete genera.    Phylogenetic analysis has revealed that basidiomycete subterranean fruiting bodies, like their ascomycete counterparts, evolved from above ground mushrooms. For example, it is likely that Rhizopogon species arose from an ancestor shared with Suillus, a mushroom forming genus.  Studies have suggested that selection for subterranean fruiting bodies among ascomycetes and basidiomycetes occurred in water-limited environments.  
The black truffle or black Périgord truffle (Tuber melanosporum), the second-most commercially valuable species, is named after the Périgord region in France.  Black truffles associate with oaks, hazelnut, cherry, and other deciduous trees and are harvested in late autumn and winter.   The genome sequence of the black truffle was published in March 2010. 
Summer or burgundy Edit
The black summer truffle (Tuber aestivum) is found across Europe and is prized for its culinary value.  Burgundy truffles (designated Tuber uncinatum, but the same species) are harvested in autumn until December and have aromatic flesh of a darker colour. These associate with various trees and shrubs. 
Tuber magnatum, the high-value white truffle or trifola d'Alba Madonna ("Truffle of the Madonna from Alba" in Italian) is found mainly in the Langhe and Montferrat areas  of the Piedmont region in northern Italy, and most famously, in the countryside around the cities of Alba and Asti.  A large percentage of Italy's white truffles also come from Molise.
In Spain, per government regulation, white summer truffles can be harvested only in May through July. 
The "whitish truffle" (Tuber borchii) is a similar species native to Tuscany, Abruzzo, Romagna, Umbria, the Marche, and Molise. It is reportedly not as aromatic as those from Piedmont, although those from Città di Castello are said to come quite close. 
Geopora spp. are important ectomycorrhizal partners of trees in woodlands and forests throughout the world.  Pinus edulis, a widespread pine species of the Southwest US, is dependent on Geopora for nutrient and water acquisition in arid environments.  Like other truffle fungi, Geopora produces subterranean sporocarps as a means of sexual reproduction.  Geopora cooperi, also known as pine truffle or fuzzy truffle, is an edible species of this genus. 
A less common truffle is "garlic truffle" (Tuber macrosporum).
In the U.S. Pacific Northwest, several species of truffle are harvested both recreationally and commercially, most notably, the Leucangium carthusianum, Oregon black truffle Tuber gibbosum, Oregon spring white truffle and Tuber oregonense, the Oregon winter white truffle. Kalapuya brunnea, the Oregon brown truffle, has also been commercially harvested and is of culinary note.
The pecan truffle (Tuber lyonii)  syn. texense  is found in the Southern United States, usually associated with pecan trees. Chefs who have experimented with them agree "they are very good and have potential as a food commodity".  Although pecan farmers used to find them along with pecans and discard them, considering them a nuisance, they sell for about $160 a pound and have been used in some gourmet restaurants. 
The term "truffle" has been applied to several other genera of similar underground fungi. The genera Terfezia and Tirmania of the family Terfeziaceae are known as the "desert truffles" of Africa and the Middle East. Pisolithus tinctorius, which was historically eaten in parts of Germany, is sometimes called "Bohemian truffle". 
Rhizopogon spp. are ectomycorrhizal members of the Basidiomycota and the order Boletales, a group of fungi that typically form mushrooms.  Like their ascomycete counterparts, these fungi are capable of creating truffle-like fruiting bodies.  Rhizopogon spp. are ecologically important in coniferous forests where they associate with various pines, firs, and Douglas fir.  In addition to their ecological importance, these fungi hold economic value, as well. Rhizopogon spp. are commonly used to inoculate coniferous seedlings in nurseries and during reforestation. 
Hysterangium spp. are ectomycorrhizal members of the Basidiomycota and the order Hysterangiales that form sporocarps similar to true truffles.  These fungi form mycelial mats of vegetative hyphae that may cover 25-40% of the forest floor in Douglas fir forests, thereby contributing to a significant portion of the biomass present in soils.  Like other ectomycorrhizal fungi, Hysterangium spp. play a role in nutrient exchange in the nitrogen cycle by accessing nitrogen unavailable to host plants and by acting as nitrogen sinks in forests. 
Glomus spp. are arbuscular mycorrhizae of the phylum Glomeromycota within the order Glomerales.  Members of this genus have low host specificity, associating with a variety of plants including hardwoods, forbs, shrubs, and grasses.  These fungi commonly occur throughout the Northern Hemisphere. 
Members of the genus Elaphomyces are commonly mistaken for truffles.
The mycelia of truffles form symbiotic, mycorrhizal relationships with the roots of several tree species including beech, birch, hazel, hornbeam, oak, pine, and poplar.  Mutualistic ectomycorrhizal fungi such as truffles provide valuable nutrients to plants in exchange for carbohydrates.  Ectomycorrhizal fungi lack the ability to survive in the soil without their plant hosts.  In fact, many of these fungi have lost the enzymes necessary for obtaining carbon through other means. For example, truffle fungi have lost their ability to degrade the cell walls of plants, limiting their capacity to decompose plant litter.  Plant hosts can also be dependent on their associated truffle fungi. Geopora, Peziza, and Tuber spp. are vital in the establishment of oak communities. 
Tuber species prefer argillaceous or calcareous soils that are well drained and neutral or alkaline.    Tuber truffles fruit throughout the year, depending on the species, and can be found buried between the leaf litter and the soil. The majority of fungal biomass is found in the humus and litter layers of soil. 
Most truffle fungi produce both asexual spores (mitospores or conidia) and sexual spores (meiospores or ascospores/basidiospores).  Conidia can be produced more readily and with less energy than ascospores and can disperse during disturbance events. Production of ascospores is energy intensive because the fungus must allocate resources to the production of large sporocarps.  Ascospores are borne within sac-like structures called asci, which are contained within the sporocarp.
Because truffle fungi produce their sexual fruiting bodies under ground, spores cannot be spread by wind and water. Therefore, nearly all truffles depend on mycophagous animal vectors for spore dispersal.  This is analogous to the dispersal of seeds in fruit of angiosperms. When the ascospores are fully developed, the truffle begin to exude volatile compounds that serve to attract animal vectors.  For successful dispersal, these spores must survive passage through the digestive tracts of animals. Ascospores have thick walls composed of chitin to help them endure the environment of animal guts. 
Animal vectors include birds, deer, and rodents such as voles, squirrels, and chipmunks.    Many species of trees, such as Quercus garryana, are dependent on the dispersal of sporocarps to inoculate isolated individuals. For example, the acorns of Q. garryana may be carried to new territory that lacks the necessary mycorrhizal fungi for establishment. 
Some mycophagous animals depend on truffles as their dominant food source. Flying squirrels, Glaucomys sabrinus, of North America play a role in a three-way symbiosis with truffles and their associated plants.  G. sabrinus is particularly adapted to finding truffles using its refined sense of smell, visual clues, and long-term memory of prosperous populations of truffles.  This intimacy between animals and truffles indirectly influences the success of mycorrhizal plant species.
After ascospores are dispersed, they remain dormant until germination is initiated by exudates excreted from host plant roots.  Following germination, hyphae form and seek out the roots of host plants. Arriving at roots, hyphae begin to form a mantle or sheath on the outer surface of root tips. Hyphae then enter the root cortex intercellularly to form the Hartig net for nutrient exchange. Hyphae can spread to other root tips colonizing the entire root system of the host.  Over time, the truffle fungus accumulates sufficient resources to form fruiting bodies.   Rate of growth is correlated with increasing photosynthetic rates in the spring as trees leaf out. 
Nutrient exchange Edit
In exchange for carbohydrates, truffle fungi provide their host plants with valuable micro- and macronutrients. Plant macronutrients include potassium, phosphorus, nitrogen, and sulfur, whereas micronutrients include iron, copper, zinc, and chloride.  In truffle fungi, as in all ectomycorrhizae, the majority of nutrient exchange occurs in the Hartig net, the intercellular hyphal network between plant root cells. A unique feature of ectomycorrhizal fungi is the formation of the mantle on outer surface of fine roots. 
Truffles have been suggested to co-locate with the orchid species Epipactis helleborine and Cephalanthera damasonium.,  though this is not always the case.
Nutrient cycling Edit
Truffle fungi are ecologically important in nutrient cycling. Plants obtain nutrients via their fine roots. Mycorrhizal fungi are much smaller than fine roots, so have a higher surface area and a greater ability to explore soils for nutrients. Acquisition of nutrients includes the uptake of phosphorus, nitrate or ammonium, iron, magnesium, and other ions.  Many ectomycorrhizal fungi form fungal mats in the upper layers of soils surrounding host plants. These mats have significantly higher concentrations of carbon and fixed nitrogen than surrounding soils.  Because these mats are nitrogen sinks, leaching of nutrients is reduced. 
Mycelial mats can also help maintain the structure of soils by holding organic matter in place and preventing erosion.  Often, these networks of mycelium provide support for smaller organisms in the soil, such as bacteria and microscopic arthropods. Bacteria feed on the exudates released by mycelium and colonize soil surrounding them.  Microscopic arthropods such as mites feed directly on mycelium and release valuable nutrients for the uptake of other organisms.  Thus, truffle fungi, along with other ectomycorrhizal fungi, facilitate a complex system of nutrient exchange between plants, animals, and microbes.
Importance in arid-land ecosystems Edit
Plant community structure is often affected by the availability of compatible mycorrhizal fungi.   In arid-land ecosystems, these fungi become essential for the survival of their host plants by enhancing ability to withstand drought.  A foundation species in arid-land ecosystems of the Southwest United States is Pinus edulis, commonly known as pinyon pine. P. edulis associates with the subterranean fungi Geopora and Rhizopogon. 
As global temperatures rise, so does the occurrence of severe droughts detrimentally affecting the survival of arid-land plants. This variability in climate has increased the mortality of P. edulis.  Therefore, the availability of compatible mycorrhizal inoculum can greatly affect the successful establishment of P. edulis seedlings.  Associated ectomycorrhizal fungi will likely play a significant role in the survival of P. edulis with continuing global climate change. [ citation needed ]
|Truffle dog||Truffle hog|
|Keen sense of smell||Keen sense of smell|
|Must be trained||Innate ability to sniff out truffles|
|Easier to control||Tendency to eat truffles once found|
Because truffles are subterranean, they are often located with the help of an animal possessing a refined sense of smell. Traditionally, pigs have been used for the extraction of truffles.  Both the female pig's natural truffle-seeking, and her usual intent to eat the truffle, are due to a compound within the truffle similar to androstenol, the sex pheromone of boar saliva, to which the sow is keenly attracted. Studies in 1990 demonstrated that the compound actively recognized by both truffle pigs and dogs is dimethyl sulfide. 
In Italy, the use of the pig to hunt truffles has been prohibited since 1985 because of damage caused by animals to truffle mycelia during the digging that dropped the production rate of the area for some years. An alternative to truffle pigs are dogs. Dogs pose an advantage in that they do not have a strong desire to eat truffles, so can be trained to locate sporocarps without digging them up. Pigs attempt to dig up truffles. 
Fly species of the genus Suilla can also detect the volatile compounds associated with subterranean fruiting bodies. These flies lay their eggs above truffles to provide food for their young. At ground level, Suilla flies can be seen flying above truffles. 
The volatile constituents responsible for the natural aroma of truffles are released by the mycelia or fruiting bodies, or derive from truffle-associated microbes. The chemical ecology of truffle volatiles is complex, interacting with plants, insects, and mammals, which contribute to spore dispersal. Depending on the truffle species, lifecycle, or location, they include:
- volatiles, which occur in all truffle species, such as dimethyl mono- (DMS), di- (DMDS) and tri- (DMTS) sulfides, as well as 2-methyl-4,5-dihydrothiophene, characteristic of the white truffle T. borchii and 2,4-Dithiapentane occurring in all species but mostly characteristic of the white truffle T. magnatum. Some of the very aromatic white truffles are notably pungent, even irritating the eye when cut or sliced.
- Metabolites of nonsulfur amino acid constituents (simple and branched-chain hydrocarbons) such as ethylene (produced by mycelia of white truffles affecting root architecture of host tree), as well as 2-methylbutanal, 2-methylpropanal, and 2-phenylethanol (also common in baker's yeast). -derived volatiles (C8-alcohols and aldehydes with a characteristic fungal odor, such as 1-octen-3-ol and 2-octenal). The former is derived from linoleic acid, and produced by mature white truffle T. borchii. derivatives appear to be produced by bacterial symbionts living in the truffle body. The most abundant of these, 3-methyl,4-5 dihydrothiophene, contributes to white truffle's aroma. 
A number of truffle species and varieties are differentiated based on their relative contents or absence of sulfides, ethers or alcohols, respectively. The sweaty-musky aroma of truffles is similar to that of the pheromone androstenol that also occurs in humans.  As of 2010 [update] , the volatile profiles of seven black and six white truffle species have been studied. 
Because of their high price  and their pungent aroma, truffles are used sparingly. Supplies can be found commercially as unadulterated fresh produce or preserved, typically in a light brine.
As the volatile aromas dissipate quicker when heated, truffles are generally served raw and shaved over warm, simple foods where their flavor will be highlighted, such as buttered pasta or eggs. Thin truffle slices may be inserted into meats, under the skins of roasted fowl, in foie gras preparations, in pâtés, or in stuffings. Some specialty cheeses contain truffles, as well. Truffles are also used for producing truffle salt and truffle honey.
While chefs once peeled truffles, in modern times, most restaurants brush the truffle carefully and shave it or dice it with the skin on so as to make the most of the valuable ingredient. Some restaurants stamp out circular discs of truffle flesh and use the skins for sauces.
Truffle oil is used as a lower-cost and convenient substitute for truffles, to provide flavouring, or to enhance the flavour and aroma of truffles in cooking. Some products called "truffle oils" contain no truffles, or include pieces of inexpensive, unprized truffle varietals, which have no culinary value, simply for show.  The vast majority is oil that has been artificially flavoured using a synthetic agent such as 2,4-dithiapentane. 
Because more aromatic molecules in truffles are soluble in alcohol, it can be used to carry a more complex and accurate truffle flavour than oil without the need for synthetic flavourings. Many commercial producers use 2,4-dithiapentane regardless, as it has become the dominant flavor most consumers, unexposed to fresh truffles but familiar with oils, associate with them. Because most Western nations do not have ingredient labeling requirements for spirits, consumers often do not know if artificial flavorings have been used.  It is used as a spirit in its own right, a cocktail mix or a food flavoring. 
Cultural and culinary significance of truffles
The first mention of truffles appears in the inscriptions of the neo-Sumerians from 20th century BCE regarding their Mesopotamian enemy's eating habits. 3 Other notable ancient records include the writings of Theophrastus, a Greek philosopher in the 4th century BCE, and the records from Roman naturalist Pliny the Elder in 1st century CE. 2
Today, truffles are found in temperate areas of Mediterranean Europe, western North America and Australia. 2 They find their way into some of the world&rsquos best restaurant kitchens within a few days (sometimes hours) of being foraged. Creamy pasta dishes, eggs, potatoes, and poultry are some traditionally popular companions for truffles. Thin slices or shavings are used to garnish the dish. Due to their perishability, seasonal availability, and high cost, not everyone can enjoy truffles. This makes truffle infused condiments like salt, olive oil, and butter quite popular among gourmands. Oprah, for instance, is said to refuse to travel without ensuring that she, her assistant, and security detail have packed surplus truffle salt! 4
Wild Mushroom Identification by Season
Temperature, time of year, and light are aspects of habitat to consider as well.
- Make note of the temperature, not only at the time of mushroom hunting but also at night. Many mushrooms fruit in the early fall, as the nights begin to grow cooler. These cool evenings tend to trigger mycelium to produce mushrooms as they indicate a change in seasons. Observing temperature changes in your environment can tell you when to begin searching for new specimens.
- The time of year is important as some mushrooms fruit mainly in the fall, others in the spring. The length and conditions of these seasons may change depending on where you live so consult a local guidebook for more information. The most famous example of seasonal fruiting is probably the morel, which is notorious for showing up mainly from April to early June.
- Finally there's light. Although mushrooms are famous for growing in the dark, most of them need a little light. They don't use it to produce food, but indirect, sustained light also triggers mushroom production. Many will grow towards the light, called "photosensitivity".
So the next time you're trying your hand at wild mushroom identification, remember to look around your prize. Observe the trees, soil, and other aspects of the environment. There's no telling what you might find next!