Although at times they are a mouthful to say, we can all
concede on some level that scientific plant names have their uses. They provide a
systematic way of
referring to plants by using unique names that dispel the confusion that common
names create. L.H. Bailey, in his
1933 book How Plants Get Their Names, explains the necessity of scientific
names with an enjoyable description of the Jerusalem cherry, which, he points
out, is neither a cherry nor from Jerusalem.
As with any other system, there are rules,
and the rules
come from some governing body, often self-appointed. Grammar rules come from our eighth grade teacher, or so it
seemed, style rules come from Strunk and White, and the rules of order for a
meeting come from Roger. But
whence the rules for plant names?
The plant classification system itself comes from
mid-18th-century Species Plantarum by Carl Linneaus. In that work, Linneaus first published the system for
organizing plants and assigning them a binomial, a two-word name for a species.
The International Association for
Plant Taxonomy (IAPT) maintains the set of rules for naming; it is called the
International Code of Botanical Nomenclature.
Makes the Rules?
The ICBN is the set of rules that provides taxonomists
the guidelines for assigning names to plants, and checking on existing names if
a controversy arises about the correctness of a plant name. When the IAPT meets, an
updated set of
rules is published and the update is referred to by the place where the meeting
was held. So, the most recent code
is called the St. Louis code, named for the International Botanical Congress
held in that city in 1999; before that, the Tokyo code (1993) was enforced.
are a scientist, reading the code is rather
dry work, even for someone who loves to learn and say scientific plant
names. The code deals with such
topics as what happens when the specific epithet is in the form of an adjective
or a noun, what is a validly published name, and how to form infraspecific
epithets. You may want to read
through the code yourself, and so here it is on the Web:
it is more likely that you are interested in plant
name topics that hit closer to home.
And one particular topic of interest is why plant names change. That, too,
is described in the code,
but let's look at some particular examples that can make sense of the
In The New Plantsman, March 1994, Brent Elliott, who is
the librarian for the Royal Horticultural Society, expressed the frustration of
many gardeners when he wrote:
"One of the liveliest and most predictable subjects of gardeners'
conversation is the problem of changes in plant names, instituted for
mysterious reasons by interfering botanists."
This was the introduction into the subject
of the many
scientific names that have been applied to the Douglas fir, Pseudotsuga
menziesii, over the last two hundred or so years. Elliott's story of the Douglas fir name changes has to do
with the rule of priority. That
rule states that the correct name of a plant is the first published correct
name. It must be correct; it must
be published; it must be first.
It began when Archibald Menzies collected a specimen
the tree while serving as naturalist on Captain George Vancouver's 1791-1795
voyage. Unfortunately, the cones
had been lost, and that made any identification or classification difficult
right from the beginning, because Linneaus's entire system was built around
categorizing and naming plants by their sexual parts.
So, the first name applied to
the Douglas fir was Pinus
taxifolia. It was a pine, because
at that time almost any conifer was considered a pine; the second word easily
described the look of the needles, which resemble a yew (Taxus). This was in 1803.
In 1825, the third name given to the Douglas fir was
Abies menziesii, suggesting that the tree be named for the man who first
collected the specimen. From there
it's a merry romp through more firs (Abies), more pines, a spruce or two
(Picea) and a couple of hemlocks (Tsuga).
All the while, the specific epithet (the second word in the name), also
bounced around. It was not until
1867 that a new genus, Pseudotsuga, was proposed, and the taxifolia was
added. But, in 1950, it was
pointed out that the specific epithet taxifolia had been misapplied when the
tree was thought to be a pine or a fir.
And so the specific epithet was changed to menziesii, which was the
first published correct name.
Got that? So,
in 1950, the Douglas fir's scientific name settled down.
clue to the fact that a plant has had other names
can be found when, after a plant name, you see parentheses and the abbreviation
"syn." For example, the
California fuchsia, Zauschneria, was formerly listed as an Epilobium, the genus
of fireweed. The listing would
appear: Zauschneria californica
(syn. Epilobium canum).
Plant names can change after years of debate-or
sometimes, the debate continues and gardeners' heads go back and forth as if we
were watching a tennis match. The
two camps held by taxonomists on the Mahonia/Berberis debate (some felt all the
species should be Berberis) appears to have decided that their really are two
genera there. On the other hand,
there is still a large contingent of taxonomists who include Pernettya in
Gaultheria, and so you may see them lumped together in some references.
times, a precipitous event causes something akin
to fruit basket mixup. Case in
point: the Alaska cedar, Monterey
cypress and their offspring, the leyland cypress.
The leyland cypress has been known
by the botanical name
x Cupressocyparis leylandii. It
was a cross between two West coast species, the Alaska cedar (then known as
Chamaecyparis nootkatensis) and the Monterey cypress (Cupressus macrocarpa)
which occurred in, of all places, Leighton Park, Wales in 1888. An intergeneric hybrid
is noted by the
"x" at the beginning of the name; the genus name for leyland cypress was formed by combining the parents'
Even before 2001, taxonomists were uncomfortable with the
placement of the Alaska cedar in the genus Chamaecyparis (the genus is
sometimes called "false cypress"). Perhaps it was really a Cupressus, in which case the leyland
would be an interspecific, not intergeneric, hybrid. But when a new conifer was discovered in Viet Nam in 2001,
it seemed to settle the controversy for all the scientists.
The new genus was given
the name Xanthocyparis, and the
species found, Xanthocyparis vietnamensis. Xanthocyparis is described as the link between true cypress
(Cupressus) and false cypress.
With what seemed like a huge sigh of relief, Chamaecyparis nootkatensis
was moved into the new genus, and renamed Xanthocyparis nootkatensis.
This meant that
the leyland cypress was still an
intergeneric hybrid, but one parent's name had been changed, and so must the
leyland's. The correct name is now
x Cuprocyparis leylandii.
Don't expect the plant name dance to stop. Now, with the ability (but perhaps not
all the funding in the world) to describe the DNA of a plant, more changes are
to come. Just within the last
couple of years, gardeners have seen the genus bugbane (Cimicifuga) moved into
the baneberry genus (Actaea). That
means that the lovely, dark-foliaged 'Hillside Black Beauty' is now Actaea
simplex 'Hillside Black Beauty'.
Next after scientific names, gardeners focus on the
cultivar names of plants—that part of a plant name within single quotes. The
rules for cultivar names are the responsibility
of an organization related to the ICBN; it is the International Code of
Nomenclature for Cultivated Plants.
The ICNCP keeps a sharp eye on cultivar names, and hopes
to clarify the whole subject for gardeners. For example, one rule passed in the late 1950s stated that
cultivar names should not sound like Latin, so that gardeners won't be confused
about which part is the scientific name and which part is the horticultural
community's name. Granted, many
plants were given cultivar names before that rule was passed, and so we
continue to find Viburnum opulus 'Roseum', whereas today that 'Roseum' would be
changed to something less latiny.
The ICNCP includes more than 70 International Cultivar
Registration Authorities (ICRA) focussing on some of the most popular groups of
garden plants; the overseeing organization is the International Society for
Horticultural Science. ICRAs are
worldwide and, in most cases, are a particular plant society. For example, the American
Society, the Heather Society and the International Oak Society, both based in
the UK, and the Bromeliad Society International in Australia are all ICRAs.
It may seem
like a lot of to-do over one little four-inch
perennial you see at the nursery.
But in fact, if we did not have all those botanists constantly sifting
through research and previously published plant names, we would soon sink into
the morass of the quirky world of common names.