As a child, you've all had (or seen) the experience of a teacher asking you (or someone else) to define a word, and when you responded by giving an example of the word's use, the teacher said, "No, I asked for a definition!" Well, teacher was wrong. People learn the vast majority of their language (grammar, vocabulary, you name it) not from definitions, but from hearing words used in context. This fact and its consequences are known under the rubric of Natural Language. The most important consequence for mycology is that words don't come pre-packaged with clear, unambiguous meanings - - instead, they have the meaning you inferred for the word when you first heard it. This meaning is personal and, while it is subject to revision as you accumulate more instances of the word's use, it is completely dependent on your personal experience of other people using the word.
[Natural Language is one of two terms made trendy in the 60's by Noam Chomsky (the other is "generative"). Over the next several decades, linguists expanded the definitions (or "original usages") of these words by using " natural language" as both a venue for research, an explanatory principle, and their actual object of study, and using "generative" for anything that they wanted to label as cool. This expansion is a good example of natural language in action. In this website, I'm going to limit my definition and discussion of natural language to the fact that the meanings of the words we use is contingent on our live experience with them.]
One effect of natural language is that if something never gets precisely defined, we'll all make up definitions for it, even if these definitions never get explicitly stated. For instance, the english expression "upwards of a hundred". This means "about a hundred", as everyone familiar with it knows. But does it mean slightly greater or less than a hundred? This is never spelled out in normal usage of the expression. So, if you poll a roomful of people, you will find that they are almost evenly split on whether it means more or less than a hundred.
But this is a very simple example, with only a few possible interpretations. A more complicated example (and more relevant for mycology) is the difference between the colors violet and purple. I see speciesdescriptions all the time that seem to be making a distinction between these colors, and I have no idea whatsoever what that distinction is. I am furthermore willing to bet money that if you took several people who do make the distinction, sat them down with color samples, and got them to label them violet or purple, they'd come out with very different responses. There is also the problem of segregated populations: fashion designers may all talk amongst themselves and come up with a consistent concept of what violet is, but odds are that it will be different from the one that fly-fisherman come up with in exactly the same way. This problem has obvious resonance not only with mycological terms, but with species concepts.
So Bulliard knew about the term adnexed, but considered it synonymous with adnate. He lacked a latin term for narrow gill attachment, so he made one up. Forty years later, Fries would start using adnate and adnexed in clear opposition to one another, but without ever defining them. People using his books had to try to identify their mushrooms from terms whose meanings were not clear, then look at the features of the mushrooms they'd identified and try to firm up their understanding of his terms from the mushrooms. It's no wonder that things got so confused.
Things are worse when you go to the terms sinuate and emarginate. Bulliard's Dictionnaire de botanique shows up the horrible truth that all these terms are really derived from the botany of vascular plants: his illustrations for these terms are of leaf shapes. Sinuate is illustrated by a white oak leaf. Well, that's clear enough. Emarginate, on the other hand, is defined as "with a piece cut out sufficiently big to look like an angle cut with scissors" and he gives two pictures, which I have crudely redrawn here. Presumably the piece cut out is at the top center of both leaves. It's hard to see how someone could decide to transfer this concept (without explanation) to mushroomgill attachment, especially without distinguishing it from the concept we now call serrate. It's especially difficult to believe that someone would do this without explaining what the term meant in its new context.
So, it's a big mess. Some of you knew this already. What I do when defining terms in this website is notify you if a term has been used in many senses over the years. I try to select a reasonable, useful meaning from the ones available, and ditch the term if I can't come up with one.
It's quite easy to trace many of these misunderstandings back to natural language. For instance, take a pair of nineteenth-century mycologists, using Fries' book. They find the mushroom shown in this picture, whose gills are given as adnexed, and identify it. One of them looks at the right-hand side of the cross-sectioned specimen and decides that this gill attachment (emarginate or sinuate, as defined in this website) is "adnexed". The other one looks at the left-hand side and decides that this is the definition of adnexed. Or, more likely, each sees both sides but interprets one side as aberrant. Or realizes that the concepts are rather difficult to apply here, and comes up with something different from anyone else. Then each mycologist writes a book (groan), and their students try to use it. Then those students each writes a book... You can see where I'm going with this. Any attempt to define these terms without a discussion of these problems is at best a primary-source interview, like those that anthropologists hold with members of other cultures. And each book should define their terms (at least for that work) explicitly, to avoid misunderstandings.
A similar problem is the intense confusion between the terms for furriness or hairiness, but here things are a little different. With these terms, it seems to be more a case of people assuming that if Author A used a different term than Author B, the feature s/he was looking at must have been different. In other words, the assumption is that hispid actually means something different from villose, and that (furthermore) the distinction is so clear that the mushroom is definitely going to stay on one side of the line for its entire life-span.
There's a further issue that doesn't seem to have been addressed here, which is the difference between descriptive and prescriptive language. Applying the term villose to a collection may actually be correct if you're just taking notes on it: this may be, irrefutably, exactly what you have in front of you at the time. This is descriptive language. However, if you then publish that description as a description of the species, it becomes prescriptive language: it doesn't describe what you saw, it tells other people what to look for. In a prescriptivecontext, the term villose implies an exclusion of other similar conditions, such as hispid, pilose, velutinate, and canescent. If you want to allow for the possibility of those conditions, you have to either list them all, which is annoying, or you just have to use a broader term like "furry", which is what I do.
There is a related problem, which is that we currently have a standard set of characters that are supposed to be listed in a description (or even a diagnosis), whether or not they are relevant in characterizing the mushroom. If, for example, I'm trying to identify something in the genus Strobilomyces, all I need to know is that it's a bolete whose cap is completely covered with shaggy black tufts of hyphae, and that its overall coloration is dark. It's also nice to know that its flesh stains red where cut or bruised, and then slowly turns black. These are features which no other fungus possesses, and are entirely adequate on their own to distinguish the genus from all other genera. I don't need to know anything about the stalk; I don't particularly need to know about the sterile margin, or its mycorrhizal associates. If these qualities are mentioned in the context of identification, they're just confusing. I may make the mistake of thinking that they are essential for the characterization of the taxon when they're not, and I may make the even more serious mistake of thinking that they're consistent when they're not. This then feeds right into the problems of ambiguity in terms that we've just been discussing.
I have tried to make a clear distinction in the key between the diagnostic features that are supposed to be taken in a prescriptive sort of way ("The mushroom is supposed to look like this; if it doesn't, you probably have another mushroom.") and the remarks under "Comments", which list features that I've often found, in a descriptive kind of way. These features are there to help reassure you that your identification is correct if they fit, but they don't disqualify your identification if they don't. I have, by and large, altogether omitted features that don't specifically help you identify your mushroom.
It's a shame that there's no official system for cleaning up terminology, the way there is with species. I think it would be wonderful to establish the priority of papilionnacé as a term for narrow gill attachment and let the two words that sound almost alike (adnexed and adnate) go back to meaning the same thing. It would be a heck of a lot easier to remember...
Another dynamic that sometimes contributes to confusion in terminology is pragmatics. Pragmatics is the branch of linguistics that addresses how one's concrete situation affects language learning and production. The pragmatics of 19th centurymycology are dominated by factors reinforcing the isolation of geographically separated mycological communities: nationalism, publications that were only intermittently available away from their point of origin, and just plain poor communication. The virtually simultaneous "discovery" of the basidium in the 1830s, in different countries and with different terminology, by Léveillé, Berkeley, Ascherson, Klotzsch, and Corda (as detailed in John Ramsbottom's (1953) Mushrooms and Toadstools, pp. 22-23) is a good example of this poor communication. That Massee(1913) was still willing to give Berkeley full credit, 75 years later, without mentioning any of the others, is a good example of the nationalism at work, deliberately prolonging the lifespan of differences in terminology and interpretation that created by more innocent circumstances.
The effect of all of this was to divide mycology into a large number of fairly isolated communities. One need not have any background in linguistics whatsoever to realize that the effect of such isolation is for each to community to develop their own dialect of their (supposedly? previously?) common language. This is a circumstance that is acknowledged by the notion of "species concept"s, but not for terminology. If Lawrence M. Leonard's (2000) "Is it sinuate or emarginate?" is taken as reasonably exhaustive, then there was no discussion of terminology in the technical literature whatsoever until the late 20th century. Previous to that, definitions of terminology were limited to popular works (starting in the 1860s) and stand-alone mycological dictionaries, of which the first seem to have been Snell(1936) and Ainsworth & Bisby(1943) .
In conclusion, we should not forget that the confusion over macroscopic, Friesian terms is not just a product of the real-life situation of 19th centurymycology - - it is also a very real situation in the practice of mycology today, and hence generates its own pragmatics. For example, the tremendous emphasis on microscopic characters that started gaining momentum around the turn of the century was a reaction to the supposed variability and lack of clarity of macroscopic characters. Maybe we should try to assess how much of that unclarity was due to the characters themselves, and how much to the language that was used to describe them.