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Northern Ontario Plant Database


Scientific Authorities

In scientific publications, a species binomial is followed by the name of the person or persons who named a species. This person is referred to as the scientific authority. Example: Comarum palustre L.: Carl Linnaeus was the first person to assign the binomial Comarum palustre to what we commonly call the marsh cinquefoil. Authority names, placed after the species name, are often shorted to an abbreviation and they are not italicized. The abbreviations for authorities mentioned in this database follow the standards defined in Brummitt and Powell's Authors of Plant Names (1992). Full names and official abbreviations for botanical authors are available online at Harvard University's Index of Botanists website.

When a species name changes, the first name validly published is called the basionym (base name) and the author of this name is called the basionym author. To show the connection to the source of the new name, botanists retain the name of the basionym author by placing it in parentheses, hence this author is often referred to as the parenthetical author. The authority of the new combination is placed after the parentheses. Example: Potentilla palustris (L.) Scop. The name Comarum palustre was published in 1753 in Linnaeus's Species Plantarum. Later, Giovanni Scopoli decided that the genus Comarum should be included in the genus Potentilla, so in 1771 he created the new combination Potentilla palustris (L.) Scop.

If the name of the species changes again, the basionym author is still retained, but the name of the author of the new combination replaces the author of the previous combination. Example: In 1837, Rafinesque moved Comarum palustre into the genus Pancovia, creating the new combination Pancovia palustris (L.) Raf. The abbreviation for Rafinesque's name replaces that of Scopoli as the author of the new combination.

When the name of a species changes, the specific epithet usually remains the same, unless, according to the ICBN rules, another specific epithet has priority in that genus. Example: Platanthera foetida Geyer ex Hook. f. (1855) has priority over Platanthera unalascensis (Spreng.) Kurtz (1894) when Piperia unalascensis (Spreng.) Rydb., the Alaskan rein orchid, is transferred back to the genus Platanthera.

What information do you need to include in an author citation?

In a scientific paper, it is necessary to include the authorities after the species name, but publications geared towards the general public do not often include the scientific authorities. While this is less confusing to the public, it can cause confusion if you are dealing with names that have several isonyms or homonyms. Without the author citation, it is impossible to know whose version of the name is being discussed.

In this database, we have included additional information with each name, which does not need to be mentioned if you are including the scientific names in a non-technical report. For example, the NOPD checklist entry for the smooth wild rose is Rosa blanda Aiton 1789, non Pursh 1814. This tells you that Aiton was the first known author to name Rosa blanda, but in 1814, Pursh created the same combination (a later isonym) for the same taxon. Since the rules of priority state that only the earliest validly published name is recognized, Aiton's name is the accepted name and Pursh's name is rejected. When this name is included in a typical report, it is correct to write just Rosa blanda Aiton. Neither the date of Aiton's publication nor Pursh's name and date are necessary, unless your purpose is to show the presence of isonyms, homonym, or other synonyms (see Definitions and Abbreviations).

The following chart compares how names are entered in this checklist (column 1) with the usual manner that such names would be written (column 2). The rationale for each change is provided in parentheses in column 2.

Entry in the NOPD checklist Typical citation form
1) Rosa blanda Aiton 1789, non Pursh 1814 1) Rosa blanda Aiton
2) Osmorhiza divaricata (Britton) Piper 1901, non Blank. 1904, nec Suksd. 1906 2) Osmorhiza divaricata (Britton) Piper
(Later isonyms do not need to be mentioned.)
3) Rosa serrulata Crép. non Raf. 3) Rosa serrulata Crép.
(Later homonyms do not need to be mentioned.)
4) Ageratum altissimum L., non Eupatorium altissimum L. 4) Ageratum altissimum L.
(Names that may be confused with the name in question do not need to be mentioned.)
5) Arnica plantaginea Pursh, and sensu Fernald 1933 5) Arnica plantaginea Pursh
(Other author's understanding of a taxon do not need to be mentioned, unless they are different from the original author's - see next example).
6) Salsola salsa sensu Nutt., non L. 6) Salsola salsa sensu Nutt. non L.
(When the sense of a species by one author differs from the intended sense of a species as established by the original author, both authors should be mentioned for clarity.)

More information on authorities: explaining 'in' and 'ex'

In the case of author citations that include the author of a text in which the name was published (if different than the author of the species name), the name of the text author is included only in the original citation. Example: Rosa humilis Marshall var. grandiflora Baker in Willmott. Baker created variety grandiflora of Rosa humilis, but it was published in Ellen Willmott's monograph "The Genus Rosa." The "in Willmott" portion of this name is a bibliographic citation and does not need to be written when including this name in a report. When this variety was moved to Rosa carolina, it becomes Rosa carolina L. var. grandiflora (Baker) Rehder. Since the basionym was published by Baker, not Willmott, only Baker's name is mentioned in the parenthetical position, even though it occurred in Willmott's monograph.

When an author citation includes the word 'ex,' it indicates that the author listed before the 'ex' did not validly publish the name, but the name was later validated by the author listed after the 'ex.' Example: Rhus rydbergii Small ex Rydb. In 1900, Rydberg created the name Rhus rydbergii, attributing the original authorship to Small, who had not validly published the name. When Greene moved the dermatitis-causing Rhus species into the genus Toxicodendron, the combination became: Toxicodendron rydbergii (Small ex Rydb.) Greene. When moved into the parenthetical position, both authors are still mentioned, since (using our example) Small's name is not valid without Rydberg's.

Example: Chenopodium album L. var. leptophyllum Moq. in DC. Christian Moquin-Tandon created the combination Chenopodium album var. leptophyllum in DeCandolle's 1849 classic publication, Prodromus. When Sereno Watson elevated this taxon to full species status in 1874, Moquin's name is moved into the parenthetical position, but DeCandolle's name is not, since he was not the author of the basionym. Watson also attributed the authorship of the combination Chenopodium leptophyllum to Nuttall, who had originally created, but not validly published, this name. Thus, the new combination becomes Chenopodium leptophyllum (Moq.) Nutt. ex S.Watson.

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