As a passionate student of both horticulture and language, this is a subject I have strong interest in. If you search the web (or a library) looking for guidance on how to pronounce a particular Latin name, you will quickly find an array of conflicting recommendations. You are also likely to see such recommendations prefaced by a remark such as the following (no, I cannot bear to link to this site):
Relax! The good news is there is NO "correct" way to pronounce them! You may pronounce them any way you wish, and you will be just as "correct" as any Ph.D. botanist. So have confidence, and just say them however feels comfortable to you. Anyone who corrects you is only showing their own ignorance, and the correct response is to just smile and say "Yes, that's what I said, (and repeat the name as you pronounced it before).
In my experience, the more strident the assertion that there is no correct pronunciation, the more scattered and arbitrary the pronunciation advice that follows. Still, the sentiment above has been expressed in milder form by a number of respected writers knowledgeable in botanical Latin, including the modern pontiff on the subject, W. T. Stearn:
How they are pronounced really matters little provided they sound pleasant and are understood by all concerned...
Now one can hardly take exception to the pragmatic assertion that the purpose of language is to communicate, and if one is communicating successfully, there is no cause for anxiety or concern. Yet it strikes me as odd that people writing about the pronunciation of botanical names so often feel obliged to include such a disclaimer. Writers on other disciplines do not. When was the last time you read a chemistry text that reassured students with "You can say OX-i-gen, ox-EYE-gen, or OH-zee-gen, and they are all correct!"
From the standpoint of linguistics, which regards the spoken language as primary and the written language as secondary, it is quite a strange circumstance that a community of speakers would not know how to say the words they use. How did this come about?
Long after the fall of the Roman Empire, Latin remained the lingua franca of Europe, particularly among the learned. Although it ceased to be a native language, it did not cease to be a spoken language. Even into the nineteenth century, classically educated people in Europe would converse in Latin, as well as writing and reading it. Because the language was in continuous use, its pronunciation changed with the locale and the era, as does the pronunciation of any language. Especially significant were the changes that occurred in England. During the Middle English period, English experienced what is known as "the great vowel shift", which dramatically changed the sounds of the long vowels: A went from "ah" to "ay", E from "eh" to "ee", and I from "ee" to "eye". Thus Old English mis (pronounced "mees") became Modern English mice. Keep in mind that this shift in pronunciation was not something people were conscious of; it happened gradually over several generations. The older pronunciations were forgotten. And the change carried the pronunciation of Latin words with it. So as "mees" changed to "mice", so linum (Latin for "flax") changed from "LEE-num" to "LYE-num". (Of course, there have been many other changes in English pronunciation between when the Romans introduced Latin to England and the present day, but these are some of the most pertinent for the present discussion.) Other pronunciation changes were happening all over Europe, so that Latin as pronounced in England was different from Latin as pronounced in Germany, which was different again from Latin as pronounced in France.
As many of our modern sciences blossomed from the seventeenth century onward, they took their terminology from Latin. Botany was no exception: following Linnaeus's system of binomial nomenclature, every species was assigned a genus name and species name, both in Latin form (although the root words from which these names were formed were often Greek or from some other language). In England, these Latin (or Latinized) names were all pronounced as Latin was pronounced in England at the time. There was at this time no disagreement over the pronunciation of words in Latin. Even those constructed on Greek roots were easy to pronounce for anyone with a classical education (just as people of our generation knew how to pronounce "internet" when the word first appeared, since although it was a new word it was made up of familiar components.) Furthermore, many technical terms were adopted straight from Latin into English, with perhaps only a minor change in form. Many of these borrowings from Latin are transparent to us today: area, species, orbit, formula, momentum.
By the late nineteenth century, linguists had worked out, based on careful study of ancient sources and comparisons between the various Romance languages, how Latin was actually pronounced in the classical era of Caesar and Cicero. Latin began to be taught according to this reconstructed classical pronunciation, rather than the English pronunciation that had been familiar up to that time. This was a positive change in terms of appreciating the previously forgotten sounds of the ancient language, but it gave rise to problems in using the Latin or Latinized technical vocabulary of the sciences. In most cases, the traditional English pronunciation was retained, as the words had already become quite familiar. Thus species remained "SPEE-sheez" (the traditional English pronunciation), rather than becoming "SPEK-ee-ess" (the classical pronunciation).
Note: I've come across a few references that erroneously use the word "traditional" to refer to the reconstructed classical pronunciation of Latin. In this context, the word "traditional" does not mean "oldest", but instead refers to what has been handed down through tradition (with changes along the way), rather than what has been reconstructed by linguists studying ancient Latin.
But for words less often encountered, such as the names of lesser-known genera and species, English speakers afer 1900 were left in a state of uncertainty. The traditional English pronunciation was no longer being taught, and fewer people had any instruction in Latin at all. So from the 20th century on, people encountering a Latin species name for the first time would either (1) use the traditional English pronunciation if they could infer it from the pronunciation of similar names they had actually heard spoken, (2) use the classical Latin pronunciation if they had learned this in school or from books, or (3) make something up. You will find all of these approaches evidenced in the pronunciation guides now in circulation, almost always mixed together without much attempt at consistency.
Botany (or biology, more broadly speaking), I think, has suffered worse from this confusion than the other sciences that make use of Latin terms, simply because we have so many names to contend with (many of which will be encountered in writing before they are ever heard), rather than a manageable set of technical terms whose pronunciation is reinforced by use in conversation. It is small wonder that writers on the subject have given up trying to maintain a pronunciation system that is shared by all.
So what is one to do, assuming that one is actually interested in pronouncing the names in a way that has some basis in linguistic tradition, rather than just arbitrary guesswork? For me, it comes down to two viable choices: (1) use the traditional English pronunciation, or (2) use a mixture of the traditional and classical systems, informed and tempered by the practices of people you converse with.
Why not just use the classical pronunciations exclusively? Surely this has the best claim to being the "real" pronuncication of Latin. The reason is that many plant names have become familiar in their traditional English pronunciation, and they are here to stay. Iris itself is a perfect example. The classical pronunciation is "EE-ris". Try this at your next local iris society meeting or at your local nursery and see how it goes. Many other examples are easy to come by. Who is going to talk of "gair-AH-ni-ums" instead of "jer-AY-ni-ums"? "SAY-dum" instead of "SEE-dum"? "nar-KISS-us" instead of "nar-SISS-us"? (If you do adopt a consistently classical pronunciation, though, you will come closer to the way many non-English speakers pronounce the names.)
My own inclination is to use the traditional English pronunciation, up to the point where it isolates me from contemporary practice in my area. An example is the term plicata, which is "pli-KAH-ta" classically and "pli-KAY-ta" traditionally. In North America, at least, I don't ever expect to hear the latter as the name for the familiar iris color pattern - or the pseudo-species for which it was named. I will, however, say "re-tik-yoo-LAY-ta", "flor-en-TYE-na", and "hoog-i-AY-na", even though I often hear "ret-tik-yoo-LAH-ta", "flor-en-TEE-na", and "hoog-i-ANN-a". The traditional English pronunciations have several advantages. We can use English words borrowed from Latin as a pronunciation guide (alpine helps us pronounce alpinus, albino helps us pronounce albinus, variegated helps us pronounce variegata, etc.) It also provides a consistency that reinforces the pronunciation of common elements in different names, and thus makes new names easier to pronounce when you encounter them. Finally, it connects us to the English-speaking botanists and gardeners of the past, who knew no other way to pronounce Latin. W. R. Dykes and Sir Michael Foster are excellent company, in my view.
If you mix traditional and classical pronunciations (provided you get your mix from listening to others, rather than randomly), then your choices are less likely to stand out in your locality, and will probably come closer to what people in your area would expect, having encountered the names only in writing. The pronunciation guide accompanying this essay uses grave and accute accents so that you can easily use either traditional long vowel sounds (ay, ee, eye, oh, yoo/oo) or classical ones (ah, eh/ay, ee, oh, oo). Also remember also that c and g are always hard in classical pronunciation.
Just in case anyone should interpret the above to imply that I'm some kind of obsessive pronunciation enforcement officer, have no fear. It is bad manners to correct anyone's pronunciation, particularly in an area where informed people can and do have different preferences. My approach is to respect others' informed choices, to encourage struggling beginners (it's much more important that they want to talk about iris species at all than that they pronounce them well), and to work to inform myself as best I can, so that I can be a resource to others if asked. In my experience the oft-cited unpleasantness of people correcting each other's pronunciation is a rarity.
Let me conclude with a story of one iris name and its pronunciation, spanning several decades. When I was a teenager, I was already interested in Latin and knew its (classical) pronunciation rules. In one of our iris society round robins (a sort of pre-internet discussion group, conducted through the quaint media of paper, typewriters, and envelopes), the question came up of how to pronounce Iris pseudacorus. I asserted that pseuda- meant "false" and that I didn't know whether corus had a long or short o in Latin, which would determine which syllable to stress. Bee Warburton, one of the iris world's luminaries, patiently explained that there is plant called Acorus, the sweet flag, that the prefix pseudo- lost its -o- in the compound, and that Acorus is stressed on the first syllable. So the pronunciation can only be "sood-ACK-or-us". It was my first encounter with the names as living words, words that could be understood if you knew about the plants as well as the language.
Recently, while attending an open house at an amazing display garden in my area, someone remarked on irises growing in a watercourse, and asked if they were Louisianas. The garden owner said they were not, but could not recall the name. He said they were the fleur-de-lis. Being helpful, I suggested pseudacorus. Because I was stressing the a isntead of the o, he didn't recognize my suggestion as being the same as the name he had read in books. I mention this because it provides a cautionary note to the oft-repeated advice to "say it however you like, people will understand". There are some advantages to using a shared pronunciation.
Finally, out of curiosity, I decided to try to verify Warburton's assertion that the a is stressed, and that it is short. Internet searches quickly revealed many web sites stating with authority that the pronunciation is "sood-AY-cor-us", many others stating with authority that it is "sood-ACK-or-us", plenty holding out for "sood-a-COR-us", and one lone site with enough honesty (or bewilderment) to offer a choice of pronunciations. None of them provided the etymology in enough detail that I could verify the vowel lengths in either Latin or Greek. In this research game, you soon find that the older the source, the more reliable, consistent, and informed it is likely to be. If you can get back to the nineteenth century, any book you find is likely to be written by someone who actually knew some Latin and Greek, and who had a good idea what the words meant and how they had been adapted. Sure enough, I eventually came upon A Manual of Scientific Terms: Pronouncing, Etymological, and Explanatory; Chiefly Comprising Terms in Botany, Natural History, Anatomy, Medicine, and Veterinary Science: with an Appendix of Specific Names, by the Reverend James Stormonth (1885, digitized by Google), wherein I learned that all three vowels are short in Greek akoros as well as in Latin acorus. Bee was right all along. Not that I doubted that.
One often finds, in pronunciation guides that are informed and careful, the advice that this ending, common in plant names, should be pronounced "oh-EYE-deez". The reasoning is sound: -ides comes from Greek -eidos, "resembling", with the -o- as a connective. Thus the i is long, and the short o is separate from it. Yet strangely, I kept enountering venerable and reliable sources suggesting it be pronounced "OY-deez". Why should that be? I learned that in the traditional English pronunciation of Latin, when two vowels are in hiatus, the first usually became long. Furthermore, oi is a diphthong in Anglo-Latin, though an uncommon one. Since most of the words with this ending are coined technical terms, not natural borrowings into Latin from Greek, early speakers of scientific Latin in England may have had some latitude in pronunciation, whether to regard the -oi- as a diphthong or not. In the cases where a coined Latin word with this ending was borrowed fully into English ("asteroid" being a prime example), the -oi- was pronounced as a diphthong. "OY-deez" is certainly more natural for English speakers than the trisyllabic alternative.
Unless otherwise noted, all text and illustrations copyright Tom Waters and all photographs copyright Tom or Karen Waters. Please do not reproduce without permission.