Over the course of the next few articles I will be applying concepts from the discipline of Psychology to the identification of mushrooms. Examples from both professional and amateur mycology will be used to illustrate processes which influence the way we see the world and classify fungi. In the first installment an argument will be made that from the first moment of sensation, through the various stages of the perceptual-cognitive process (to the final conceptual framework of the taxonomist or collector) the eye and brain operate so as to filter, shape and reify material as we attempt to give meaning and structure to what we see. 

In subsequent installments the importance of meaning, memory, cognition, language, concept formation and abstract symbolic manipulation will be stressed.  Classical taxonomic schemes will be reviewed and compared to some challenges posed by recent DNA restructuring of the clades.  An argument will be made that different operational definitions, focusing on differing aspects of the physical world, yield different meanings of that reality. These different taxonomies are best seen as complimentary views of the same world.

Part 0ne: Sensation and Perception in Mushroom Identification:

Here is a problem for those of us who collect mushrooms. They don’t come with name tags attached. So, when we want to refer to them, say to search out their edible, toxic, or pharmacological properties, we must “identify” them, give them names – symbols – and use these as substitutes for the actual objects in our baskets or bellies.

The problem is that the process of naming and identifying the various species we encounter is quite complex. Often it is done “intuitively” based upon a simple glance at a “familiar” shape; at other times it is enormously complex, involving the use of microscopes, chemical reagents, and densely written, often conflicting, treatises. 

What I hope to do in this article is to examine this process from a psychological point of view… But Wait! I can almost hear some readers at this point saying “Oh, NO! Not another account of Phallus impudicus and the impropriety of young women viewing the slimy sinful disgust.” 

Fear not, Dear Reader. We are not going there. Modern psychological understandings have long since left that Freudian sexual stuff in the dust, (even though his insights have forever altered and infused our popular, secular culture.) For various reasons even college courses in introductory psychology usually omit much of the “nuts and bolts” of the biological workings of that neural instrument we call “the brain”. This is a topic usually left for the second, third, fourth course, or perhaps never. Many graduates know less about how their bodies and brains work than they do about their cell phones, MP3 players, or GPS devices. 

So let’s begin here, with a short review of how our innate microscope (the eyes) and computer (the brain) work together as we attempt to see, recognize, identify, and name that mushroom we may have just collected. A bit down the line we will look at some specific issues related to the concept of species at it relates to mycology and encounter some of the very abstract understandings of DNA analysis as they impinges upon our understanding of the mushrooms we hold and have. 

Some of this will seem like common sense, obvious when it captures our attention. Mushrooms don’t come with name tags. (Duh! Well, Yeaaah! Says our Dear Reader.)    Naming, therefore involves perception and cognition. (Yes…says he.) Perception and cognition are but endpoints of the same continuum; they exist as a process. (Hummm, perhaps you better go on.)


In this continuum, the process of sensation can be considered as a baseline. A major conclusion drawn here is that we do not have access to veridical transduction: which is to say that energy from the world as it exists outside of our nervous system must be changed – transduced – into other forms of energy used within the nervous system in order for sensation to occur. And the process is not perfect. Photons, for example, must excite various specialized neurons within the retina (or skin) and be transformed into an electrochemical language common to the rest of the neural tissue.

Humans, as we know, differ with regard to the ability to see color. In my early years of mushrooming I was fortunate to collect with a member of the New York Mycological Association who was color blind. He was one of the sharpest naturalists in the group, and it was a pleasure to collect with him. Working with him enabled me to clarify and sharpen my own technique. In part his gift, and skill, seemed to come from the fact that he could not distinguish colors. Much like a deer, he became exquisitely attuned to aspects of his visual world that escape normally sighted collectors. Often, while collecting, he would approach me with a mushroom and ask for my opinion of its color. “Would you call this ‘brown’”, he might say, emphasizing the color. “In every other aspect it agrees with the description of ‘brunnescens.’”   

Years after meeting him I underwent vitrectomy, retinal repair and cataract lens implant of my right eye. I was absolutely amazed at the different color reading I received from the two eyes. What was pinkish to my left (undamaged) eye was bluish to my right.  I came to understand that this was perfectly normal, an artifact of the normal aging of the lens and vitreous humor of the eye, both of which accumulate matter and filter spectra thereby giving a “warmer” look to the world as we age. My retinal surgeon explained that the cataract implant in the right eye, without the filters, gave a “truer rendition” of the “real color” of the visual world. Knock me down with a feather! What was I seeing all of those years?

Because we are living biological creatures, veridical (perfect 1 to 1) transduction (sensing of stimuli from the external world) is not available to us. Errors and variation creep into our identification process from the very beginning. (Well, that’s neat, [might say our Dear Reader], but is there more?)

Cells of the retina, although able to fire to single quantum of energy, are placed at the very back of the eyeball, under several layers of tissue, and actually point away from the iris and the external world. The visual input, by design, is exceedingly well buffered and filtered. What is “out there” is not seen as much as it is “created”. (Sure! Now this is Really Far Out!)

Consider also that the eyeball itself continually flutters from side to side in a jerky motion called the “saccadic movement” (from the French “flick of the sail”). An image stabilized on the retina (by a specialized contact lens) fades and disappears. Sensation therefore is a matter of differential energy input. From a practical point of view, this means that subtle aspects of color, size, shape, texture, often go unseen, unnoticed: “Nonexistent” until pointed out by a “trained eye”. 

One aspect of these “subtle differences” is referred to as a JND (Just Noticeable Difference). With careful training the normal person can become attuned to and more sensitive to these nuances. Most of us, for example cannot “see” the subtle flicker of a 60 cycle per second light bulb, but most would notice the slower, 30 CPS, flicker of the earlier hydroelectric juice distributed at Niagara Falls. With training however the JND can be altered so that the range of detection moves closer to the 60CPS range. Most subjects so trained find the flicker to be disturbing, sort of like a perpetual strobe effect.

In a similar manner, special training is necessary to distinguish between the subtle differences of color, texture, and spore size of mushrooms. It takes practice and a trained eye to appreciate and meaningfully use the Ridgeway Color Standards for hue and saturation of color, the ISCC-NBS Centroid Color Charts, or the “Q” Standards for the average length/breadth ratio of mushroom spores.  Globose, subglobose, broadly elliptical are enlightening terms, but within this context, analogous to only the 30 CPS flicker of Niagara, not the steadier glow of the more modern grid.

Returning to the saccadic flicker of the eye, what we “see” as an image is actually a highly processed dynamic overlay of sensations, the borders of which are distributed as the arithmetic mean of a normal probability curve, with its attendant sets of average interior and exterior values. The information which strikes the retina (itself brain tissue) is therefore encoded much as a TV image might be, and is then sent to a receiver in the rear of the brain (the area striata of the visual lobe) for decoding. Once decoding is processed the information must then be sent to yet other forward parts of the brain for interpretation. Throughout, the interpretation is altered by information previously processed and held in our memory banks.

The conclusion, reiterated, is that we do not “see” the world as much as we “create” it. 

Ergo, “Mushrooms” do not exist, we create them. There may be various sensations emanating from the forest floor which impinge upon our sense receptors, but we have to learn to group and process this sensory information into images and attribute to them an external reality that we call a “mushroom”. We later learn to attend to sensory subtleties and perceive/differentiate/discriminate between the creations/inventions of a “Lactarius”  “Russula”, or “Amanita”. (Wow!  And all the time I thought you guys who talked like that simply ate too much “Psilocybe” Heh, Heh!)

Well, there is actually more, but enough. Let’s go on to Perception, the second stage of this process. These ideas should be more obvious.


As we have seen, learning to attend to subtle nuances is part of the perceptual process.  Now most of the time we think of learning as a conscious event; you know, like learning how to deliver the baseball into the strike zone. You throw with spin on the ball. The ball curves away from the bat and the batter swings and misses. You take pleasure – are rewarded – by the consequences of your action and learn to throw a better curve ball. But not all learning is conscious, or even under the influence of external rewards. Some learning appears to be shaped by processes wired into our neural tapestry, preordained and almost instinctual. 

This appears to hold for perceptual organization. Gestalt psychologists, who pioneered the study of perception, noticed that there are several major processes that shape how we see and organize the world. These are often called Gestalt Principles. Four are Contiguity, Similarity, Continuity, and Closure. Items grouped according to these forces “feel right”; we are rewarded accordingly, and come to see those observations as part of the natural world.

The Principle of Contiguity refers to the fact that we tend to group together in our mind items that are close to one another in space (or time). If two items, say mushrooms, grow side by side there is a tendency to see them as members of the same class or group, perhaps the same species. So, we tend to “see” fairy rings as expressions of a single expanding mycelium and the fruiting bodies which penetrate the duff or soil as the same mushroom. Dr. Cornelis Bas placed Amanita excelsa and A. spissa in synonymy (in part) because he had “seen both organisms growing in the same fairy ring, the “excelsa” form in loose, humus rich soil, and the “spissa” form in dry sandtrack”. (Jekins1986)

Similarly Nancy Smith Weber (1972) developed her concept of Helvella lacunosa (in part) by contiguous temporal and spatial collections. In her text, following a discussion of Helvella lacunosa, sulcata and palustris, she centers in on her concept of H. lacunosa which…. 

“…can almost be characterized as variable, but the species actually varies within definite limits. In the fall of 1968, in northern Idaho, H. lacunosa was the most common species of Discomycete. Over 900 specimens of it were seen by a single collector in one day. It was quite variable in color, apothecial shape, and size, but the basic morphology of the stipe and the extremes of apothecial shape were relatively constant.  For example, both stipe and hymenium varied from nearly white to black and all possible combinations of light and dark stipes and apothecia were observed.  However, in isolated fruitings, all specimens were consistent in shape and color.  No significant breaks in the spectrum of color or shape variation were observed.  However, if only a few specimens representing separate points in the spectrum of variants are examined, one might believe that several taxa are represented.  This may have happened in Europe and may explain, in part, why so many varieties and new species have been described in the H. lacunosa group.” 

This method of comparison is also evident in her study of Morchella angusticeps, leading her to the conclusion that the “small blacks” and the “big blacks” are both members of the same species. “At this time I am of the opinion that the evidence does not seem to support recognizing more than one “black morel” at the species level in Michigan”, she concluded. (Weber 1988) 

On a smaller scale this can also be seen in the collections of Homer House, Peck’s immediate successor at the New York State Museum. In the Herbarium are several boxes of “mixed types” collected by him. House, more a botanist than a mycologist, was more interested in vascular plants than fungi. His method was to “collect large quantities of fungi [from] a single host species, perhaps one nearby his home or office, and [later] carefully sort through the material to find fungi…This practice led to some interesting discoveries as well as a few blunders.” One of his assumptions seems to have been that fruiting bodies present on the same host at the same time were representatives of the same fungi. (Leonardi and Haines in ms) 

At forays we may have seen, perhaps encouraged, a similar but looser “vacuum cleaner” approach to contiguous collecting. It is a technique often used by neophyte collectors. On trip after trip they will return with baskets indiscriminately loaded with the fungal detritus of an area which then is dumped ceremoniously onto the collecting table. Such habits continued at home will almost surely lead to more than “a few blunders”. 

Authors of reputable field guides are well aware of the problems which can result from the influence of this pattern of perceptual grouping and issue warnings in their texts. They remind us, for example, to be aware of collecting the deadly Clitocybe dealbata which might infiltrate an otherwise edible fairy ring of Marasmius oreades. (Lincoff (1981; Miller and Miller 2006)

The Principle of Similarity:  “If it walks like a duck, and quacks like a duck, it must be a duck!”

The principle of Similarity holds a particular place of honor for taxonomists. It is their bread and butter. Things that look alike are seen as belonging together, and morphological features have long been the province of naturalists everywhere – as Darwin himself  puts it in The Origin of Species, “I look at the term species as one arbitrarily given for the sake of convenience as a set of individuals closely resembling one another.” (Cited by Weiner 1994)

Consider the Polypores:  (The following synopsis is From Overholts 1953)

For Linnaeus, if it had pores it was a Boletus. – All twelve of his Bolete species we now consider members of the family Polyporaceae. Schaeffer followed this lead and kept all of the pored Polypores in the tribe Boleti based on what we would call “gross morphological features”. It looks like a duck. (He also did one better by illustrating a species of Morchella as Phallus. One of my students during a September foray reversed this treatment by proudly producing a somewhat weathered Phallus ravenelii calling it a “Fall Morel”. Apparently a follower of McIlvaine, she declared it “delicious”, having eaten it several times in the past!)

Persoon, and then Fries placed an emphasis on morphological similarities of the fertile hymenium and in the Systema Mycologicum (1821) Fries separated the chickens from the ducks recognizing Boletus and Polyporus as separate genera of the order “Pileati”. Over the next fifty years, he split and lumped and by 1874 (Hymenomycetes Europaei) recognized eight kinds of ducks within the Polypore flock; Lenzites, Daedalea, Cyclomyces, Favolus, Hexagona, Trametes, Polystictus and Polyporus. 

A succession of other authors followed who worked and reworked the Polypores, tending them into a number of other, often conflicting, segregate genera, a gaggle, perhaps.  By 1940 Cooke had his ducks in line and concluded that forty-six generic names were valid. Overholts resisted and herded them together into a flight of twelve, basically following the Friesian system. He stated his vision of the flock clearly when he said…

“it is extremely doubtful whether among the several other classifications proposed any is more practical, or perhaps even more natural” [than the Friesian system] …In a group that varies in as many ways as does the large share of the genus Polyporus it will be found almost if not quite impossible to show relationships to any better advantage by a multitude of generic segregates than by retaining all species in a single large genus.  And if the demands of a natural arrangement cannot be met, wherein lies the value of a multiplication of generic names?” 

Overholts died before his text could be finished, and it fell upon Josiah Lowe to see it to press in 1950.  By 1977 however, Alexander Smith, in the Preface to the Third Edition of this classic text, listed the new names of forty-three “modern” genera based upon a more refined classification scheme. By this time the ducks had apparently molted into eclipse plumage based upon microscopic, hyphal and spore characteristics. 

With advances in technology taxonomists are able to see similarities between finer and finer, heretofore obscure, characteristics and the move to segregate genera and species refinement continues. (This tendency towards finer and finer discrimination presumably could continue unhindered until it faced the limits set by Heisenberg’s Principle of Uncertainty at the sub-atomic level.)

In the two volume North American Polypores, by Gilbertson and Ryvarden (1986) I count some ninety-six genera listed in their Synoptic Key to Genera spread over four pages. I must confess that for me it is at times difficult to nearly impossible to find species, even ones that I know well, within this classification scheme.

“Fomes rimosus”, for example shows up only as a chance parenthetical under “Cultural characteristics” of Phellinus robineae (Murr.) A. Ames (P602). This name is based upon one of the ‘other classifications’ that Overholts took issue with (above). In this case knowledge that Black Locust is Robinia, and that Phellinus has at times been used synonymously with Fomes helps us to see how authors of even a century past were dividing up the barnyard birds. Without that small, twelve letter, parenthetical however, I would have not been able to easily refer to details of this fungus without entering this 885 page text from the beginning. The same is true for several other fungi that I have turned to in this text.

Historians tell us that revisionists, those of us who “see” the world differently, can, if they change their language sufficiently, make a clean break with the past. The example of Chairman Mao, who simply changed the Chinese language used in his Little Red Book and effectively split off Modern Communism from its Confucian roots, is often given as a definitive use of this technique. Similar revisionist tendencies also occur in natural history!

The flock is getting larger, less floristic and natural, based more and more upon smaller and smaller units of similarity. The consequent analytic dexterity of the specialist, replete with technological sophistication, and necessary as it is for scientific advancement, nevertheless becomes more and more burdensome, and perhaps less and less relevant to the layperson and generalist. When we need DNA analysis of the feathers to know what’s a duck and what’s not the day of the naturalist will be over. But I digress; more about this later.

Before we leave the Principle of Similarity let us simply note one of it’s  more common expressions in mycology, that of  “seeing”  an American mushroom to be the same as a European one simply because they look alike in a picture book or from memory. I am confident that any reader of this article can easily supply numbers of examples. (Think “Jack o’ Lantern”, “Caesars Mushroom” or “Death Cap”.) 

The Principle of  Continuity refers to the tendency of the perceptual system to retain an original organization - a “gestalt” as the German Psychologists called it - even in the face of  changing evidence, as in, “Once a Commie, always a Commie”, or “once a Bolete, always a Bolete”, or…“Once a pictus, always a pictus.”

Ernst Both (1993) has done a great service by committing his study of Boletes to print. If you want to get to know your Bolete a bit better, check it out in this Compendium. His discussion of the well known “Painted Bolete”, Suillus pictus Peck, for example, includes treatment of eight synonyms (and two other Boletes also called “pictus”) and concludes with this statement: 

“According to Palm & Stewart… the correct name for this taxon is Suillus spraguei (Berkeley & Curtis in Berkeley) Kuntze.  It is very unfortunate that such a widely used epithet as “pictus” would have to be replaced with a totally meaningless epithet, “spraguei” because of some technicality.  The name “Suillus pictus” should and can be conserved because it is an economically important entity, not only forming mycorrhizae with Pinus strobes but also because it may become an important source of food wherever its host is planted.” 

“Conservation” in this sense is a process whereby a previous name is, by rule, retained in the literature. In the passage cited above, “pictus” has higher “associational value” to Dr. Both and therefore a much richer meaning to him and presumably other mycologists than does “spraguei” a name which refers to Charles Sprague, a friend of Frost. (In a later installment of this article we shall see that one of the meanings of "meaning" is the associational value of the term, "associational value" being the number of referents a term has.)

We can see this principle of Continuity used with even sharper effect when we look at Dr. Both’s discussion of Gastroboletus lariscinus Singer and Both. 

“According to Baura, Szaro & Bruns (1992) this is a recent mutant of Suillus grevillei, genetically identical with it and thus a synonym of it.  However, there are a number of macro- and microscopic differences which warrant to maintain it as an autonomous species.” 

In this case the fungus was originally described by Singer and Both in 1972, and despite evidence discovered twenty years later showing it to be genetically identical to another species, an argument is advanced to retain the previous name. Something quite important seems to be going on here and I will attempt to fold it into a discussion of DNA typing in a future installment.

In the meantime, one more example from the Boletes.  Oh Boletus, that most difficult of all genera: The stories here are legion!

In discussing two of Pecks mushrooms, Boletus subglabripes and B. subglabripes var. corrugis, Smith and Thiers (1971) take issue with Singer who placed these species in Leccinum. Several arguments are advanced for keeping both species in Boletus (thus illustrating the principle of Continuity) but in a surprising turn they then argue that var, corrugis, for somewhat similar reasons, be given a new name as a distinct species, Boletus hortonii, and there it rests. (It has been my impression and I must confess to forgetting where I first heard this, that the differences are due to the weather, hortonii, with the wrinkled top, being the form subglabripes takes in wet rainy conditions. I can’t find the reference, but my records show that all of my collections of hortonii were during very wet summers. Chalk one up to continuity for influencing my perception.)

The Principle of Closure refers to the tendency to complete a gestalt (perceptual organization) where gaps and holes exist. We “fill in” the missing pieces and see the complete form as if it were a completed image, perception or thought. We therefore tend to see things that are only/primarily/partly in our mind. We leap to conclusions and form snap judgments. 

Dr. Jerome Groopman of the Harvard Medical School describes in his book, How Doctors Think (2007), the consequences of misdiagnoses made by these premature closures. These “anchoring mistakes” as he calls them are a leading cause of physician error.

It is embarrassing to think of how many times I have seen a mushroom and made a snap judgment based upon a single characteristic that, at the time, seemed completely diagnostic but which later turned out to be completely wrong. Because of this my own personal rule of edibility is to follow a new mushroom for a season or two before I commit it to the test of my gut.

I recall vividly one mushroom poisoning case I worked on where the patient mistook a yard full of Amanita virosa for Lepiota naucina. The naucina had fruited in the yard of her friend, an experienced collector, the previous year and they had both enjoyed a meal cooked from their find. When white mushrooms came up in the same place a year later, the friend announced the fruiting during a telephone chat and the patient collected and ate a basketful of Amanita. She was also a mushroom collector of many years standing, having learned at her family’s side in her native Czechoslovakia, but had nevertheless mistaken the poisonous mushroom for the one she had previously enjoyed. (Incidentally, she survived and lived to eat other meals of wild mushrooms but with permanent liver, kidney, and heart damage. The fact that she was a nurse and her husband a physician may have helped with the excellent treatment she received. I never did find out why the husband refused to eat her mushroom dish!  She also proclaimed them “not all that good”.) 

In the face of premature closure, Dr Groopman counsels his fellow physicians to always ask of their diagnosis, “What else could it be?” and, “Might two things be going on at the same time?” We might ask a similar question for mushrooms, particularly those “known only from their type location”, as the following example illustrates.

In 1960, M. Pantidou, near Paul Smith College in the Adirondack Region of New York State, collected a pure white Suillus with a flaring glutinous ring in mixed coniferous woods and gave it the name Suillus hololeucus – “entirely white”.  It is hard to know what is in the mind of another, but it is probably fair to say, from the name alone, that Pantidou placed quite a bit of importance on the color of the mushroom. A decade later, Snell and Dick (1970) included the description, with drawings of spores and cystidia in The Boleti of Northeastern North America. 

In 1987 the Northeastern Mycological Foray was held at Paul Smith. Nearly three hundred sets of eyes, many (like me) with Snell and Dick in their dorm room, looked for this mushroom for four days without avail. If not a distinct species, what else could it be? And, what else might have been going on when it was found and named?

A pencil notation in my copy of Snell and Dick reads, “Now thought to be a white form of grevillei. Pomerleau and others. NEMF1987 ” Dr. Pomerleau, it turns out, had been present when the original collection was made, and at the time, made the observation that it was not a new species, simply a white form of Suillus grevillei.(see Both  p154) Others apparently have agreed with this observation. You will not find it in the authoritative Boletes of Michigan (Smith and Thiers 1971), Nova Scotian Boletes (Grund and Harrison 1976), or the most recent North American Boletes (Bessete et. al. 2000).   A mushroom, perhaps, whose time has come and gone.

A similar “phantom mushroom” is Boletus fulvus, collected near Philadelphia Pa, around 1885, by Charles McIlvaine. There was communication between Peck and McIlvaine about this tawny yellow mushroom that grew in clusters on rotting stumps and, according to Ernst Both (p.130), “It must be assumed that Peck based his description on [a drawing] and McIlvaine’s notes rather than on actual specimens, as he did with most other of McIlvaine’s boletes.” There is no type… but McIlvaine reported that it “was excellent in flavor, rather spongy, but fine.” Various authors have since attempted to validate this species, usually by synonymy with other species.

A final example shows how premature closure was avoided as the author, in this case Charles Peck, kept an open mind and considered several options as his thinking progressed. (From Both, p.225):

“A study of Peck’s field notes (unpublished notebook 6:51, 1874-76) revealed a peculiar story. Peck started to describe a collection under the heading “Boletus speciosus Frost”, beginning with a discussion of how his specimens differed, being “rather smaller than the type but scarcely more than a variety I think.”  At some point he must have decided that he was dealing with a different species and crossed out the sentence cited above.  He also erased (the notes were written with a pencil) “speciosus” but left the author’s name (Frost). Underneath he wrote “Boletus pulcherripes Pk. N. sp.”  This was then crossed out and “Peckii” written above it (where “speciosus” had been erased), thus creating “Boletus Peckii Frost.”   The label in the box containing the type also reads “Boletus pulcherripes Pk.” with “pulcherripes” crossed out and “Peckii” written above it.”… “As [Roy] Halling points out, there is no evidence that Frost sent specimens of this taxon to Peck, and a manuscript description by Frost is lacking. According to Halling, ‘the type of B. peckii is a specimen collected and described by Peck.’ ” 

This example seems as good a place to end this installment as any other.  What I have tried to show is that through various psychological/biological processes we create internal mental symbols – names - from the flux of sensory constellations gathered from the external world. This process is so automatic and well greased that we can easily forget that these symbols, mushroom names in this case, have been abstracted from the reality from which they spring.  I have applied these concepts here to naturalistic observation, but a case can be made that they are central to more 'objective' taxonomies as well. 

In the next installment, we will look at the cognitive end of the perceptual-cognitive continuum: memory and meaning in the identification process.


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Both, E. 1993. The Boletes of North America: A Compendium. Buffalo Museum of Science, Buffalo NY.

Gilbertson, R.L. and L. Ryvarden. 1986. North American Polypores. Fungiflora Oslow Norway 

Gregory, R.L. 1997.Eye and Brain: the Psychology of Seeing, Princeton University Press, Princeton NJ 5th ed..

Groopman, J. 2007.  How Doctors Think. Houghton Mifflin, Boston Mass. 2007

Grund, D.W. and A.K.Harrison.1976.  Nova Scotian Boletes.  Bibliotheca Mycologica Vol 47  

Jenkins, D. 1986. Amanita of North America. Mad River Press. Eureka CA 

Largent, D., D. Johnson and R. Watling. 1977. How To Identify Mushrooms To Genus III: Microscopic Features. Mad River Press; Eureka CA 

Leonardi, L. and Haines, J. The New York State Museum, in ms. The Mycological Work of Homer House. 

Lincoff, G. H. 1981. The Audubon Society Field Guide to North American Mushrooms. Alfred A. Knopf, New York

McKnight, K. H. 1977. A note on the ISCC-NBS Centroid Color Charts. McIlvainea 3 (1) p4-11

Miller, O.K. and H.H. Miller. 2006. North American Mushrooms: A Field Guide to Edible and Inedible Fungi. A Falcon Guide Guilford CT

Moore-Landecker, E. 1982. Fundamentals of the Fungi 2nd. Ed. Prentice-Hall Englewood Cliffs NJ   

Overholts, L.O. and J.L. Howe. 1953. The Polyporaceae of the United States, Alaska and Canada. University of Michigan Press, Ann Arbor Michigan, 1953 esp. P1-10

Smith, A. H. and H.D. Thiers. 1971. The Boletes of Michigan. The University of Michigan Press, Ann Arbor  

Snell, W.H. and E,A. Dick. 1970. The Boleti of Northeastern North America. Verlag von J. Cramer, Lehre Germany 

Weber, N. S. 1972. The Genus Helvella in Michigan. The Michigan Botanist V.11, 1972 

Weber, N. S. 1988.  A Morel Hunter’s Companion:  A Guide to the True and False Morels of Michigan. Two Peninsula Press. Lansing Mich. 

Weiner, J. 1994. The Beak of the Finch: A Story of Evolution in Our Time. Vintage Books Random House NY

Wood, S.E. and E.G. Wood. 1996. The World of Psychology 2nd ed.  Allyn and Bacon, Needham Heights, MA 1996