The Naming of Plants
Arthur R. Kruckeberg
Professor of Botany, University of Washington
NOTE - Botanical names are a mystery, and sometimes an irritation, to some rhododendron buffs while to others they are interesting, meaningful and convey a bit of the romance of distant lands and legendary characters. This article by Dr. Kruckeberg, although not written especially for a rhododendron audience contains answers to many of the questions frequently asked. It appeared in the Summer, 1964, issue of the University of Washington Arboretum Bulletin and is Part II of a series. We are indebted to the author and to the Arboretum Foundation for permission to publish it in the A. R. S. Bulletin.
Since the first installment of these notes on plant names in the last number of the "Arboretum Bulletin," I hope that the reader has continued to encounter Latin botanical names and has asked himself questions about them. You might have met a binomial like Townsendia rothrockii and been perplexed at the lack of information content in such a name. Both the generic name and the specific name are Latinized personal names; they tell you nothing about the nature of the plant in question. Or, you may have puzzled over a "jawbreaker" like Eccremocarpus scaber and wonder how in the world to pronounce it. To resolve some of these questions, we had better confront plant names analytically. We will take a close look at the kinds of names one encounters in botanical literature, the history of the binomial, and some of the rules of pronunciation and grammar.
What variations on plant names do we encounter all within the framework of the binomial? There are essentially four classes of generic and specific names. In the previous paragraph I used the genus name, Townsendia. This example of the commemorative epithet honors a little-known eastern amateur botanist, David Townsend. Kings, rogues, botanists, patrons and lovers, all have been eulogized in this way. The addition of "ia" to a personal name is a sure route to immortality. Just look at these commemoratives: Linnaea, Kalmia, Lewisia, Kolkwitzia, Magnolia, Jepsonia, Jeffersonia, and so on through the floras of the world! Linnaea, the delightful trailing twin-flower, is named for Carolus Linnaeus, the father of systematic botany. Kalmia, the mountain laurel, is named for one of Linnaeus' students, Peter Kalm. You would be certain to recognize that Lewisia is named for Merriwether Lewis of the Lewis and Clark expedition. William Clark is commemorated in the genus Clarkia, a delightful group of annuals so common in the spring floras of the Pacific Coast.
A more academic class of generic epithets is the classical descriptive name. Here, Greek or Latin, or sometimes a mismatch of both ancient tongues, are used to depict some characteristic of the genus in question. Thus the genus Liriodendron is translated from the classic language as "lily tree"; Xanthorhiza means "yellow root"; Oxydendron means "sour tree"; Cladothamnus means "branched shrub"; Enkianthus means "pregnant flower"; etc. Occasionally, generic names have been derived from the original native word. A botanist in the tropics would find that many of the genera he finds there are Latinized versions of the original native name. Two examples from the Asiatic flora are Tsuga, which is the Japanese name for hemlock, and Ginkgo, the Chinese name for that famous and sacred tree of temple gardens. The last category of generic names is both an amusing and intriguing one-the so-called fanciful, poetical, or mythological name. Here are four names which typify this kind of generic epithet. Dodecatheon means "twelve gods"; Theobroma, the generic name for the cocoa plant, means "god's food" Phyllodoce, Calypso and Narcissus are characters in Greek mythology. Now test yourself. Pick up any book which abounds in botanical names and see if you can identify various kinds of generic names just outlined. You should be able to pick out commemorative, classical, or Latinized native names, and even some of the fanciful names or those that have mythological allusion.
Of the four categories of species names, the descriptive and commemorative groups of names are the commonest. Such simple descriptive adjectives as rubra (red), nana (dwarf), repens (prostrate growth), saxatilis (growing in rocks) etc. are ubiquitous examples. Sometimes the descriptive adjective is compound, as in angustifolia ("narrow" and "leaf"), cordifolia ("heart-shaped leaf"), racemiflora (flowers in a racemose inflorescence). Occasionally, a specific name is taken from the generic name in another group - thus we find the specific name bignonioides, which means "like bignonia," or acerifolia ("leaves like a maple"). A great many of the more recent specific epithets are simply commemorative generic names. Thus, you would find on any page of Rehder's "Manual of Cultivated Trees and Shurbs," plants with proper names as the specific epithet, such as Thunbergii, Wilsonii, Kerneri Greyana, Forrestii, Mildredae. Parenthetically, I should mention that, whereas in the past commemorative specific names have been capitalized, the current recommendation of the International Rules is to de-capitalize both commemorative and place names. It is largely left to the discretion of the user as to whether he capitalizes or de-capitalizes such names. The last group consists of species names which indeed are nouns. In the binomials, Pyrus malus and Prunus laurocerasus, the specific epithets are nouns. Usually such names were formerly generic; thus the species in question which was once placed in another genus now uses the former genus name as a specific epithet.
The inquisitive reader may wonder about the meaning of specific epithets. A number of references can satisfy curiosity on this score. I have before me a book by H. I. Featherley called "The Taxonomic Terminology of Higher Plants." The latter portion of this book contains a list of common specific epithets and their meanings. Old subscribers to the Arboretum Bulletin will recall that for several years a continuing series of lists of such names and their meanings appeared regularly in The Bulletin. These lists are particularly fascinating because many of those used almost exclusively in the regal genus Rhododendron are transcribed and their meanings given. Another source is the introduction in the first volume of L. H. Bailey's "Cyclopedia of Horticulture." Part I of the Royal Horticultural Society's "Rhododendron Handbook" (1963) gives the English derivatives for all of the species listed in that volume. The meanings of many generic names can be found towards the end of each generic synopsis in such books as Bailey's "Manual of Cultivated Plants," Rehder's "Manual of Cultivated Trees and Shrubs," or, if it is a. genus which is quite local in our own flora, the five volume series on the "Vascular Plants of the Pacific Northwest," by C. L. Hitchcock, et al., is another source. So curiosity can be satisfied, memory aided and information content increased when you delve into meanings of some of the common names encountered in horticultural and botanical literature.
Now for a little history. Somewhere during the course of our high school or college training, most of us were indoctrinated, however fleetingly, with the idea that Latin botanical names and the 18th century Swede, Carolus Linnaeus, are inextricably linked. Indeed, Linnaeus contributed more than anyone else to the codifying, naming and cataloging of the then-known plants of the world. He is the father of systematic botany. In 1753, Linnaeus published the all-important work, "Species Plantarum." This compendium in Latin of all the known plants of the period serves today as the starting point for botanical nomenclature. Succinct and pithy Latin statements followed the generic name and out in the margin was a single name in italics; at the time this so called trivial name was meant to be a reference or index term for the particular plant in question. The species name of Linnaeus was actually the more lengthy phrase or sentence. I quote such a combination of generic names, the multi-word species name, and the trivial epithet from "Species Plantarum":
"1. Plantago foliis ovatis glabris, nudo scapo tereti, spica flosculis imbricatis-major." Here you have the generic name, the compound species name and the trivial name as it appeared in 1753. What has come down to us in the form of the present binomial is the generic name and the trivial name joined together, that is, Plantago major. Thus, the birth of the present-day binomial was somewhat of an unexpected, but blessed, event. Linnaeus' intention was to use the generic name with a polynomial specific name; he wanted his specific name to serve as a series of descriptive words by which each species was to be differentiated at a glance from all others in the genus. The Linnaean polynomial species name is roughly equivalent to the diagnosis found in present-day botanical works. A diagnosis is a series of "telescoped" phrases of description, succinctly defining the morphological boundary of the species in question. My only point in dragging you through all of this, though, is to remind you that the binomial-the two words, genus and species-came into being through an accidental coupling of the Linnaean or even pre-Linnaean generic name with the inconspicuous, marginal "trivial" name.
We can do little but skim over the thorny problems of pronunciation and grammar in the forest of botanical names. Strict conformity to the classicist's rules of pronunciation of Latin and Greek names would cause, I am sure, embarrassment among even professional botanists who have used their own or inherited pronunciation for years on end. Europeans tend to pronounce Latin binomials largely as they would have pronounced the Latin that they learned in school. This is not so in the New World. Pronunciation seems to be inherited from teacher to pupil and I can offer no great solace to those who are looking for pat rules to pronunciation. Some taxonomic works, like Jepson's "Flora of California-" show accent marks on generic and specific names. This - of course - is a big help. There is usually little difficulty in dealing with the pronunciation of commemorative names; one simply pronounces the name of the man and adds (in the case of a generic name) "ia," or in the case of a specific name the "ii" or single "i." Thus - one would say Jonesii. In all other names of Latin or Greek origin - the coward's way out is to pronounce each syllable and hope that the next to the last syllable is the one to accent. There does remain one rather exceptional suffix to specific names - the one called "unlucky" by Dr. C. B. Bradley in his quaint note on accentuation of Latin names given in Jepson's "Flora." The suffix "-oides" is generally mispronounced as though one were saying such words as ovoid - thyroid and mastoid. "All such tabloids-" says Dr. Bradley, "Are of modern manufacture and suited to the haste and impatience of our modern life; but '-oides' is a leisurely and dignified mouth-filling tri-syllable and has been such at least ever since the Trojan war." The grammatical rules for binomials apply particularly to the specific epithet. Since these are largely adjectives they must agree grammatically with the generic name. The generic name is always singular in number and either masculine - feminine or neuter. What follows is a sampling of such specific epithets with three case endings.
Masculine Feminine Neuter Meaning albus alba album white niger nigra nigrum black viridis viridis viride green acer acris acre acid, sharp japonicus japonica japonicum Japanese vulgaris vulgaris vulgare common
Commemorative names take the possessive case and thus end in -i or -ii- regardless of the gender of the generic name - if the person honored is a man. Here are some examples: Baileyi, one i; Nuttallii, two i's; Jonesii, two i's. Thus - in most cases such specific epithets of commemorative type end in double "i." A rather rare exception is when the commemorative word ends in "-ey" or "-er"; it is then followed by a single "i" - thus Baileyi, Kerneri and Rehderi. If the honorific refers to a woman - then the proper ending is always "ae," as in Edithae, Margeritae, Mildredae, etc. Here is a cute variation on this immediate theme: if two or more persons are being honored - as two brothers or a man and wife - the ending would be "orum"; the plural possessive - as in Davisiorum. Gender for generic names varies depending upon the nature of the name thus - most commemorative genera - such as Magnolia, Kernera, Jepsonia, Grayia, end in "a" and are usually feminine. Generic names ending in "um" are neuter - and those ending in "us" are usually masculine. A rather odd exception is that for many trees the generic name - although ending in "-us-" is considered feminine and therefore would take a correspondingly feminine form of the specific name: Thus Quercus alba, rather than Q. albus; or Pinus monticola, not P. monticolus.
Sometimes the ending gives a clue to the meaning that is intended by the specific epithet. Thus - if the epithet is derived from a geographical name - it is usually adjectival and takes the ending "-ensis," "-anus," "inus," Besseya wyonningensis, Iris virginiana, Rubus columbianus, and Acer pensylvanicum. Habitat preference of plants is often indicated by the suffix "icola," as in rupicola or saxicola, and silvi- cola-meaning, respectively- "living in the rocks-" and "living in the forest."
It is hoped by now that the justification for the binomial, its usages, its pronunciations - its grammatical procedures, etc. are at least incipiently understood by the reader. It should also be apparent - especially if you were to scan a list of binomials in a catalog or a floristic list or a manual of systematic botany that the information content of these binomials is rather minimal. They don't reveal much about the plant they name. But the same gap exists in everyday communication: most names in any language mean very little by themselves but take on meaning when associated with an object. That this is true of botanical nomenclature will become even more apparent when we chuckle over some quaint botanical anagrams. Some practitioners of the art of nomenclature have resorted to twists and inversions of established generic names in order to manufacture more generic names with minimum effort. A good example is the lily family: the old established name of Allium (for all onion species) was borrowed to name a closely related group of plants in the California flora; the taxonomist - lacking a generic name - turned Allium around to make Muilla the generic name for this related group. Here are some more examples of this droll practice: the name of Edwin Palmer is used anagrammatically in the generic name now Malperia; Psoralea becomes Parosela; Filago becomes Gifola; Inula becomes Luina; Onagra becomes Angora; Mitella becomes Tellima; Asarum becomes Saruma; there are two anagrams for the genus Liatris; Trilisa and Litrisa. Cheap erudition to get two names for the price of one! Yet these bits of nonsense are indeed part of the accepted and official lists of generic names.
I close these sketchy notes on plant names with a word of counsel and encouragement. You should eye a Latin name boldly - pronounce it without hesitation, and learn to use it according to the few simple rules that are now available to you. Your skill in their use will increase immeasurably once you begin using them.