Biol 324 Introduction to Seed Plant Taxonomy


I. Why Latin names?

  1. - Economy. Arum maculatum has one Latin name but nearly a dozen English common names including: “Adder's Tongue”, “Wake Robin”, “Cuckoo Pint”, “Lords & Ladies”, “Jack in the Pulpit”, and many in nearly all other European languages.
  2. - Precision. “Adder’s tongue” may refer to Ophioglossum, Arum and (in North America) Erythronium (common names can apply to other species….can lead to confusion).
  3. - Universality. Latin avoids having to choose between languages. Botany has its roots in Europe during the Middle Ages (and early post-middle ages) when Latin was the lingua franca of Europe.

Example: Arum maculatum (Adder’s Tongue etc) – it is a widespread European plant so has many names from the languages of the countries in which it occurs (maybe up to 100 names). In addition to the many English common names for this plant there are a number of other ones in other languages:
French: “gouet tacheté” “pied de ceau”, “goult commun”
German: “Gefleckte Aronstab”, “Ronenkraut”

II. Pronunciation of Botanical Latin

  • - Stress: generally on the antepenultimate syllable (two from last syllable): Ranu'nculus auri'comus, Ranuncula'ceae,
  • but compound names are an exception: Pseudotsu'ga.
  • - Traditional vs reformed (Anglo) academic pronunciation. Main differences are in -ae-, -i- and soft/hard c: graeci, Caesar E.g.: graeci (Greece) Traditional pronunciation: gree-c-eye. Reformed academic pronunciation: gr–eye-k-ee. No real “right” way, but there are traditions. Romans probably used hard consonants (eg. C’s and G’s) English soft c’s and soft g’s. Caesar – soft c, although hard c in German (like Kaiser which was derived from caesar)
  • - Pronunciation of non-Latin proper nouns - follow original language (up to a point!): menziesii (Roman pronunciation is not useful for Scottish surnames) – pronounce it how the person would have pronounced it.

III. Botanical Latin
- With its roots in Medieval Latin, botanical Latin has since evolved into a distinctive technical language
- Until 2011, the use of Latin was mandated and regulated by the International Code of Botanical Nomenclature (ICBN). Now English is acceptable for valid descriptions of new taxa, as was already allowed by the Zoological Code. Advantages of the old system of describing in Latin that are frequently cited is that it was universal and that it put a hurdle in front of frivolous description of new taxa.

IV. From phrase names to binomials
- Before 1753 pickerelweed, Pontederia cordata, was known as: Pontederia foliis cordatis, floribus spicatus. This is a “polynomial” or “phrase name” (polynomial)
- Carl von Linné (Carolus Linnaeus) standardized nomenclature on binomials in 1753 in his book “Species Plantarum”. a compendium of all known species in the world. He used binomials consistently throughout. Unlike others who used binomials in the past he applied it to all organisms known in his time in Europe. He standardized the name of species by using the name as a tag, not a full description. In consequence, 1753 is taken as the starting point for botanical nomenclature in order to apply the principle of priority (i.e. the valid name is the first name - after 1753, prior names are correct unless there is a darn good reason to change it). Carolus Linnaeus (1707-1778) - a Swede of great self confidence - is therefore credited as the main champion of a uniform binomial system.

Parts of the binomial

  • - A typical binomial such as: Pseudotsuga menziesii (Mirbel) Franco, the Douglas Fir, consists of three parts: genus, specific epithet and authority
  • - The genus (kind or noun) is Pseudotsuga
  • - The specific epithet, menziesii, is an adjectival qualifier. It is not a name in its own right: “E. coli” not “coli
  • - The authority is the person who first validly described it. In this case Mirbel described it as Abies menziesii in 1825 and Franco (in 1950) transferred it into the correct genus. Curiously, it had been described earlier (as Pinus taxifolia by Lambert in 1803) but this was invalid (Salisbury had described another P. taxifolia in 1796).

Example: Douglas fir - Pseudotsuga menziesii. Common name from David Douglas (Scottish collector). Specific epithet commemorates Archibald Menzies (another Scottish collector)

V. The Rules of Botanical Nomenclature

(a) The Rulebook - Early Days

  • Linnaeus published some rules and principles for naming plants in his Philosophia Botanica in 1751. Philosophia Botanica – 1751: include rules such as no two genera with the same name, no two species in a genus with same name, principle of priority, etc.
  • In 1813 Augustin de Candolle outlined nomenclatural procedures in his “Theorie élémentaire de la botanique”.
  • In 1821 Steudel published his “Nomenclator botanicus”
  • Alphonse de Candolle suggested an international congress of botanists to standardize nomenclature, held in 1867.

(b) The International Code of Botanical Nomenclature (ICBN)

  • 1st International Botanical Congress, Paris, 1867. A revised version of De Candolle's rules accepted (Paris Code), tweaked at the second congress in Vienna in 1905 (Vienna Code)
  • Major spat over interpretation between British botanists at Kew Gardens, and American botanists at the New York Botanical Garden (who refused to accept the Paris Code)
  • A rebel code: 1892 meeting at Rochester, New York Botanical Garden proposed modifications to the Paris Code became in 1907 the "American
  • Code" (not everyone in the states accepted the American Code, Harvard for example)
  • Finally resolved at the 5th International Botanical Congress in Cambridge, England in 1930. Compromises! Cambridge code – first truly universal code.
  • Major changes to the code in 2011 (18th International Botanical Congress in Melbourne). The code itself was renamed the "International Code of Nomenclature of algae, fungi, and plants". Electronic publication of new taxa is now allowed (effective 1 January 2012). English or Latin is now acceptable for the validating diagnosis of a new name (effective 1 January 2012).

How to name a new species
(1) Check that your name has not been used before: The Kew Index (Index Kewensis) – Darwin helped fund this project
(2) Publish in accordance with the code, i.e. in a scientific journal or book, not in a popular magazine or seed catalog (although old names published in seed catalogs before the rule was made are still valid). Electronic publications are now acceptable.
(3) Write a Latin or English description (or diagnosis). English has only been acceptable from 1 January 2012.
(4) Designate a type specimen of the plant and deposit in a herbarium.

Example of Latin diagnosis:
Cyrtandra cleopatrae H.J. Atkins & Cronk, sp. nov. Ab indumento aureorubro et floribus lilacinis distinguitur. Type: Philippines, Palawan, Cleopatra’s Needle, 22 i 1998 [long description in English follows….]
The diagnosis is the short Latin description.


  • - Since 1935 every species or subspecific taxon must be associated with a single herbarium specimen, the type.
  • - The type anchors a name (invalid names and synonyms still have types)
  • - As the rule dates only from 1935, many older names have no explicitly designated types
  • - Rules allow retroactive designation of types

Type specimens

  • - HOLOTYPE - single specimen (or other element) designated by the author as the type
  • - ISOTYPE - a duplicate (from same gathering) of the holotype
  • - LECTOTYPE - specimen chosen as type from the original material (if there is no holotype)
  • - NEOTYPE - a specimen chosen as type if all the original material is lost
  • - PARATYPE - a specimen (additional to holotype) cited by the author of the original description

Holotype of Corispermum hookeri Mosyakin var. pseudodeclinatum Mosyakin from UBC herbarium (Burnaby lake 1965)
Holotype of Polystichum kwakiutlii Wagner from UBC herbarium (Alice Arm, BC, 1934)
Isotype of Crataegus atrovirens Phipps and O’Kennon from UBC herbarium (Okanagan, BC, 2000 - holotype in University of Western Ontario)

The taxonomic hierarchy

  • - “Linnaean taxonomy” has ranks: Kingdom, Subkingdom, Division, Subdivision, Class, Subclass, Order, Suborder, Family, Subfamily, Tribe, Subtribe, Genus, Subgenus, Section, Species, Subspecies, Variety, Forma
  • - Useful for informatics, teaching and learning - not a reflection of nature
  • - International Code specifies certain endings: -ales for order, -aceae for family (with 8 permitted exceptions: Compositae, Cruciferae, Gramineae,
  • Labiatae, Leguminosae, Palmae, Umbelliferae)

Hierarchy-free taxonomy: Phylocode (

  • - Ranks have no biological basis - therefore a push for a rank-free taxonomy
  • - First international meeting of the Phylocode in Paris (!) in 2004
  • - Worked out procedures for defining and naming clades - eventual aim is to have a web-based ‘clade finding’ database
  • - Presently controversial and divisive… the future?

Nomina conservanda

  • - Rules of priority can be circumvented by a vote at a congress to “conserve names” (as nomina conservanda)
  • - Camas, a plant in the lily family with blue flowers, was named as the genus Camassia by Lindley in 1832, and has long been known by that name
  • - However, it had earlier been named Quamasia by the eccentric botanist Rafinesque in 1818
  • - The genus Camassia was conserved by a vote at the Cambridge Congress in 1930 to avoid confusing name changes for these common plants

Cultivated plants

  • - Names of cultivated plants must follow the International Code of Botanical Nomenclature, but present additional complications
  • - So, additional rules: International Code of Nomenclature of Cultivated Plants for plants with "fancy" names
  • - A cultivar (cultivated variety) is a distinguishable assemblage of cultivated plants
  • - Cultivar names are to be not more than three words in a modern language (not Latinized) e.g. Rosa ‘Peace’ or Rosa cv. Peace.

Osteospermum ‘Pink whirls’ - “cultivar” coined by L.H. Bailey as a contraction of Cultivated + variety. Naming governed by the International Code of Nomenclature for Cultivated Plants (ICNCP)

Naming of hybrids

  • - Interspecific hybrid formula (with multiplication sign) Trochetiopsis ebenus × Trochetiopsis erythroxylon
  • - Or give it a new name (preceded by multiplication sign) Trochetiopsis × benjamini Cronk (follow the rules of the International Code of Botanical Nomenclature)
  • - Intergeneric hybrid formula: Cupressus macrocarpa × Chamaecyparis nootkatensis
  • - Or, new genus preceded by multiplication sign: ×Cupressocyparis leylandii
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