HerbalEGram: Volume 7, Number 11, November 2010
The Plant List: The First Comprehensive Inventory of Most Known Plant Species
“If the names are unknown, knowledge of the things also
perishes.”1 –Carl Linnaeus
A single plant can be given multiple scientific names over
time.2
More than 3,000 scientific names exist for only 19 species of Mentha, for example, and thousands of additional plants
have multiple names (A. Tucker, e-mail, September 25, 2010). This is the result of plant systematists disagreeing with the original author’s naming, an unawareness that particular plants have already been named, or changing plant names to reflect evolving knowledge of relationships among plant species. Based on the
widely used “principle of priority,” the “correct” name of a species should be the first name published according to
guidelines set out in the International Code of Botanical
Nomenclature.3 Often, the
oldest plant names are found in the 1753 book Species Plantarum
written by Carl Linnaeus, a Swedish botanist who is referred to as the father
of taxonomy.
Still, these numerous names continue to cause confusion and
problems, especially in the case of geographically widespread plants and
commercially used plants like medicinal herbs. “We need clear, definitive names to facilitate
communication among plant scientists and those in the commercial world, to be
sure that we are all using the same name in the same way,” said John Wiersema,
a botanist at the US National Germplasm Resources Laboratory and director of
the GRIN (Germplasm Resources Information Network)
database (e-mail, October 28, 1010). “Any piece of information on a
particular taxon is largely meaningless if the name to which it is associated
cannot be accurately represented.”
Seeking to solve this problem, the Royal Botanic Gardens,
Kew, and the Missouri Botanical Garden (MOBOT) are currently creating a more
definitive and comprehensive list of plant names that indicates which names are
accepted as correct and which are synonyms.4 “The Plant List,” as the project is
called, was started by Kew and MOBOT in 2008 as an initiative addressing the
Global Strategy for Plant Conservation’s (GSPC) first target goal, which calls
for “a working list of all known plant species” by 2010. According to GSPC’s
website, such a list “is considered to be a fundamental requirement for plant
conservation.”5 The GSPC was
enacted in 2002 by the Convention on Biological Diversity, an international
treaty that aims to stop the “continuing loss” of the earth’s plant diversity,
as well as to encourage sustainable use and benefit sharing of plants.6
Botanists and other scientists, as well as information technology
specialists at Kew and MOBOT have been developing and testing a new process to
generate the list, which consists of merging existing resources through an
automated, rules-based approach.4
The heuristic informatics method captures taxonomic knowledge into a rulebase,
and computers are then used to aid in sorting out the millions of plant name
records from Tropicos, Kew’s World Checklist of Selected Plant Families, The
International Compositae [daisy family] Alliance, International Legume [Fabaceae] Database and Information Service (ILDIS), and plant name information from the
International Plant Name Index (IPNI).
Several media sources have reported that the project will
eventually cut the global list of plant names by 600,000, making the number of
plant species names about 400,000.7
The project is not exactly cutting plant names from existence, however. “The
significance of the Plant List,” said a Kew spokesperson, “is not to
provide a few names and delete the non-current ones, but rather to identify the
names which are used and have been used in the past, and as far as possible
link the names which refer to the same species to facilitate information
retrieval and study” (B. Friedlander, e-mail, October 29, 2010).
“There are around 1,000,000 Latin names for plant
species,” said the spokesperson. “The estimates for the number of [actual]
plant species vary from around 250,000 to 440,000. Our work on the Plant
List to date suggests that the number of species is likely to be nearer the
high end of that range. Thus plants have on average between 2 and 3 names;
plants which are widespread and used tend to have several synonyms. This
obviously is a problem. Some work we have done at Kew suggests that if you
search online resources for a medicinal or nutritional plant using just one of
the alternative names of a species, you might only find 20% of the information
about the species. The point of the Plant List is to alert people
that more than one name for a species might exist and if they are interested in
finding out about that species, they need to search using the alternative names
(synonyms).”
According to the Kew spokesperson, who noted that the
project is still a work in progress, the list currently contains 301,000
accepted species names, 480,000 synonym names, and 240,000 remain un-assessed
as being either accepted or synonyms. Remaining work includes the adding of
important data sets to the resource, such as key names resources on legumes, composites, and grasses, so that the working list is as comprehensive as
possible.4
Kew recognizes that the list has its limitations, including a lack of coverage
of ferns and fern allies (pteridophytes, about 10,000 species) and algae (about
30,000 known species), variable completeness and accuracy in synonymy
information for flowering plants other than monocots, and weak coverage of
Southeast Asia and genera that start with letters in the latter half of the
alphabet.
“It will not be perfect, but for the first time we will
concentrate the available information in one place,” said the spokesperson.
“One of the reasons this has not been done before is that different sources of
synonymy information sometimes conflict and these differences need to be
resolved.” The final list is set to be published online sometime between the
2010 winter holidays and New Year.
Though Kew and MOBOT did not work with the American Herbal
Products Association (AHPA), which publishes the smaller subset of common and
Latin names of most herbs used in commerce in the United States, Herbs of
Commerce, 2nd edition, this will
not affect the quality of the final product, said Michael McGuffin, AHPA’s
president (e-mail, October 25, 2010). “The institutions involved are highly
authoritative,” he said, “and there is every reason to believe that they will
produce an excellent and comprehensive final product.” Still, Herbs
of Commerce will remain as is. “The
KEW/MOBOT project appears to be of a very broad scope,” he continued. “The
purpose of Herbs of Commerce
seeks to provide a unified nomenclature for just over 2,000 herbs used in
dietary supplements. These decisions were made on a case-by-case basis, usually
deciding in favor of names that reflected or facilitated common use.”
Likewise, GRIN will continue to base its plant
classifications on primary sources, such as taxonomic articles published in
scientific literature, and will use secondary sources, such as The Plant List,
“only when more primary sources of information are lacking, or perhaps to alert
us to the need to further evaluate a particular taxon,” said Wiersema. Though
there has been no organized effort similar to The Plant List between GRIN and
its partners, taxonomic experts from these organizations continuously try to
indicate and employ the most “correct” and current taxonomic acceptance of any
name, he continued. According to Wiersema, the resources being used for The
Plant List, which have been critically reviewed by taxonomic specialists for
certain groups, will be adequate for some plant families. “For many other
families this remains to be seen,” he added. A reviewer of this article noted that, while The Plant List will be imperfect, a list with errors and omissions is a better starting place than no list at all and that the manpower and funding to create a totally complete list of all names do not exist.
Before Linnaeus published Species Plantarum, biologists used various naming practices, which
often included long series of Latin names, such as one of the pre-Linnaean
names for the common briar—Rosa sylvestris alba cum rubore, folio
glabro.8 Additionally, these names could be altered whenever a biologist wanted to do
so. About this time, many new
botanical and animal specimens were being brought back to Europe from the New
World, further increasing the need for a more definitive and organized
nomenclature system.
In Species Plantarum,
Linnaeus introduced the binomial system of scientific naming by combining the
genus name and the specific, descriptive epithet designating the species. For
example, the scientific binomial of garlic is written as Allium
sativum, Allium being the genus, sativum being the epithet, and Allium sativum being the species. Thus his name for common briar
became Rosa canina. Though this
system has been used throughout much of history, it was not until 1930 that
international representatives officially agreed upon using it and Species
Plantarum as the source for oldest
botanical names.9 Among
additional requirements laid out in this agreement—the International Code of
Botanical Nomenclature—is the rule that to be official, botanical names must
be published in a normal botanical publication that is delivered to at least 2
botanical organizations.
—Lindsay Stafford
References
1. Linnaeus C. Philosophia Botanica
(1751), aphorism 210. Trans. Frans A. Stafleu, Linnaeus and the Linnaeans: The
Spreading of their Ideas in Systematic Botany, 1735-1789 (1971).
2. Permitted and quarantine species list. Government of Western Australia
Department of Agriculture and Food website. Available at: www.agric.wa.gov.au/PC_93105.html -
syn. Accessed October 25, 2010.
5. Target I: a list of all plants. Global Strategy for Plant Conservation website.
Available at: www.plants2010.org. Accessed October 20, 2010.
6. Global Strategy for Plant Conservation introduction. Convention on Biological
Diversity website. Available at: www.cbd.int/gspc/intro.shtml.
Accessed October 20, 2010.
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