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Understanding Scientific Names and Words

    In both my books North American Landscape Trees (1996) and Wild Plants of Greater Seattle (2001), editors chopped out most of the information I had written about scientific names of plants. The editors thought that I supplied too much detail. For those of you who desire the detail, here follows an unabridged version.

    Scientific names are the international currency in plant information exchange. This book contains many, including a few alternates or synonyms. Be warned: the cited synonymy is incomplete; those included are but a tiny fraction of the total. Some of the synonyms designated are literally equal or valid alternates --but most are invalid for one reason or another. Some were not the oldest, or were misapplied by botanists or horticulturists, or were never validly published. As a dictionary does with words, this book records usage, and usage often breaks rules or is otherwise improper.
    All English names or adopted foreign ones (whether truly common or merely coined by book-writers) are typeset in regular print or small capitals; all scientific ones are italicized. Most scientific names are Latin or Latinized from Greek or other languages; some, such as Tsuga, are even transliterated Japanese.
    Scientific names are not necessarily apt or literal. The International Code of Botanic Nomenclature (St Louis Code; 2000) does not insist on this. For example, many plants whose specific name is japonica are actually not natives of Japan, but rather of China --albeit long cultivated in Japan. It goes without saying that everyday English names are often fanciful --Kentucky bluegrass is green and from Europe, Canada thistle is European, and so forth.
    Every scientific name has an author, the botanist(s) who first validly published the name. This book never credits the authors of either the family or generic names; and does so only where necessary for specific names. Usually the botanists' names are abbreviated. In ordinary conversation, and in commerce, there is no need for the precision afforded by citing authors of plant names. But in cases of misapplied names, to omit the authority names is often irresponsible --their inclusion hurts no one and yet helps many researchers.
    Alas, scientific judgement has been, is, and shall be divided, so one expert's species can be another's subspecies; one scholar's concept of "valid publication" may fail to meet the criteria of another. Readers familiar with standard floras will find some names preferred in this volume are not in agreement with the judgement of other authors. This is inevitable. Disagreement is easy to find. Even when no disagreement exists, the advance of learning itself also necessitates some name changes. Yes, it is annoying when familiar names are changed; but so it has been, so it shall be. An author must examine and compare every applicable reference available, then judge what seems the best or proper name. The approach adopted in selecting names for this volume has been conservative --to defer to consensus where it exists; otherwise, to usually accept the nomenclature preferred by contemporary generic specialists, regardless whether such specialists are termed "lumpers" or "splitters." However, recognition of apomictic microspecies (as in Rubus, Hieracium and Taraxacum), is not adopted.
    Unfortunately the oft-repeated phrase "there is only one true scientific name for each plant" is untrue. What is true is that for any particular rank (such as species or subspecies) there is only one valid combination (the oldest that fulfills the requirements of valid publication). In any case, with the numerous cross references in this book, readers will be able to locate a plant by one name or another. Readers are free to reject any names given preference to, if an equally valid proposal is available. For example, Mahonia nervosa or Berberis nervosa --neither is right or wrong; one must be chosen. It is difficult for ordinary students to tell which synonymous names are invalid (obligatory name changes), and which are legitimate contemporary alternatives (optional name changes).
    There is still a great deal of work to be done in plant classification. Presently, the different genera are divided into species according to historic chance, frankly, by botanists of varying critical ability and judgement. Different judges interpret the same law or goal variously. If a rigidly applied system of taxonomic uniformity were somehow imposed (God forbid), the result would be a turmoil of name changes, with certain species sunk into synonymy, and numerous varietates elevated to species status, genera shattered and recombined, etc. We must be allowed room to disagree in civil fashion.
    Capitalization of selected specific names puzzles many people. Most professors, perhaps to make life simpler, tell students to always capitalize generic names and never capitalize specific ones. The international rules, however (see photo above), allow capitalization for specific names derived from one of the following categories:

1) a person's name (Pseudotsuga Menziesii --after Archibald Menzies);
2) a vernacular name (Gaultheria Shallon --an "Indian" vernacular for it);
3) a generic name (Anthemis Cotula --meaning "Cotula-like Anthemis").

    Sometimes people use capitals incorrectly. This happens mostly with geographic names. Even though the states Pennsylvania and Washington are named after William Penn and George Washington, the plants recorded with the geographic terms pennsylvanica or washingtonensis remain uncapitalized because they are not directly named after a person. If you choose to use capitals where permissible, be aware that some people bristle at the practice, and some editors refuse to allow it. In 1949, L.H. Bailey said of such intolerance: "The capitalizing of the apposites is not only essential to truth but to the dignity and significance of language; present practice of decapitalizing all specific names, as an editorial expedient, is only a concession to supposed convenience and inactive memory and has no potency in an historical treatment."
    Another well known botanist, M.L. Fernald, echoed and elaborated on Bailey's opinion in 1950:

"Old generic names (such as in Euphorbia Peplus) taken over as specific epithets, aboriginal names (as in Euphorbia Ipecacuanhæ) similarly applied, and personal genitives (such as in Euphorbia Geyeri) are written with initial capitals. This practice of the great founders and leaders of our science is, however, with the present tendency to "standardize" everything and to avoid the mental effort of trying to understand the meanings of names, in danger of becoming overthrown by a hasty and superficial majority. If that time comes Silybum Marianum, named for the Virgin Mary, will to many Americans indicate "coming from Maryland;" the specific name of Zea Mays (from the aboriginal name now rendered as Maize) will be untranslatable; and Fumaria Bastardii (honoring the distinguished French botanist, Toussaint Bastard) will seem to mean "of a bastard." The retention of the initial capital has much of value; its rejection is too often a source of misunderstanding."
(from the Preface to Gray's Manual of Botany; 1950)

Below, ranked from broader categories to narrower, are the levels of scientific plant-classification used in Wild Plants of Greater Seattle. The first three are most important:

    FAMILY (plural families). A group of related genera. Always fully capitalized and ending in the ligature Æ in Wild Plants of Greater Seattle (for example, ACERACEÆ; the Maple Family). Wild Plants of Greater Seattle has 135 families. The international rules, after centuries of contrary usage, changed and now disapprove of ligatures, but do allow the diæresis (¨). However, as ligatures help pronunciation by indicating silent letters, and do no harm, here they are retained in scientific names --not English equivalents (hence Spiræa as the genus, and spirea as the common name; Pæonia and peony, etc.).
    GENUS (plural genera). A group of related species. Always initially capitalized, and italicized in this book (for example, Acer, the maple). Wild Plants of Greater Seattle has just over 500 genera.
    SPECIES (plural species; abbreviated sp. in the singular and spp. in the plural). The basic unit of classification. Usually uncapitalized, and always italicized in this book (for example, macrophyllum). For example, Acer macrophyllum (bigleaf maple) is one of the species in the genus Acer. Wild Plants of Greater Seattle has more than 1,000 species.

These next two levels are far less important:
    SUBSPECIES (plural subspecies; abbreviated subsp. or ssp.). A significant geographic race of a species.
    VARIETAS (plural varietates; abbreviated var.). A minor race not deserving subspecies status; considered the same as subspecies by some botanists.

    HYBRIDS [indicated by ×] Often treated as equal in rank to species and included in lists of species. The international rules prefer squeezing the multiplication sign right next to the name (Æsculus ×carnea); like many other works, the present volume inserts a space (Æsculus × carnea). The few hybrids in Wild Plants of Greater Seattle are designated in one of three different ways:

    1) Æsculus × carnea
A botanical epithet covering all crosses between Æsculus Hippocastanum and Æsculus Pavia.

    2) Coreopsis grandiflora × Coreopsis lanceolata
Direct parentage (useful where no specific epithet has yet been given).

    3) Rosa 'Dorothy Perkins'
This third method inconsistently does not use the multiplication sign (×). It is used in any of the following cases:
* A known hybrid, but parentage unknown, nor is there a specific botanical epithet for the cross.
* Parentage known, but there is no specific botanical epithet for the cross.
* Parentage is unknown, but the plant may be a hybrid.

Horticulturists may employ the category cultivar (abbreviated cv.), often to indicate a clone, whether of a species or a hybrid. It is an abbreviation of "cultivated variety." Older books generally used the term "variety" for what we now call cultivars. But that usage did not differentiate between naturally-occurring wild varietates of scientific nomenclature, and the genetically-identical (or practically so) cultivated varieties named by nurseries and gardeners. In Wild Plants of Greater Seattle few cultivars are cited, and are indicated by single quotes (Rosa 'Dorothy Perkins').

    (TECHNICAL NOTE: In Internet Explorer, at least on my Macintosh, the proper multiplication sign indicating hybridity shows up on web pages such as this. But on my version of Netscape Navigator --and perhaps other browsers-- the proper muliplication sign does not show. And thus in most of my web-pages I have gone ahead and used the letter x to indicate hybrids.)


Arthur Lee Jacobson plant expert
Arthur Lee Jacobson plant expert
Arthur Lee Jacobson plant expert
Arthur Lee Jacobson plant expert
Arthur Lee Jacobson plant expert
Arthur Lee Jacobson plant expert
Arthur Lee Jacobson plant expert
Arthur Lee Jacobson plant expert
Arthur Lee Jacobson plant expert
Arthur Lee Jacobson plant expert
Arthur Lee Jacobson plant expert
Arthur Lee Jacobson plant expert
Arthur Lee Jacobson plant expert
Arthur Lee Jacobson plant expert

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