[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]

Re: name game

Scott Hieber might have hit the nail on the head when he wrote:
"...I long for future technology -- UPC cards on
every plant and the code reveals the DNA identity"

There are two separate but related issues at work here - taxonomy and
nomenclature. Taxonomy deals with how plants stand in relation to others,
usually in a hierarchical classification scheme. It has to do with grouping
similar and related plants together, traditionally based upon morphology
(i.e. structure). The theory being (in very general terms) that the closer
the structural similarities between two plants, the closer the "family
relationship". This can get bunged up when totally unrelated plants share
similar structures but those structures have come from quite different

For example, flowering plants have traditionally been classified as being
either dicots or monocots, with each group having a set of clearly
distinguishing characteristics. There were always some plants which didn't
quite "fit" into this scheme, but they were "made" to fit into the taxonomic
classification (i.e. Cronquist, and many others). Recent work with DNA
analysis (for example, by Chase et al) has shown that while the "monocots"
is probably a valid "group" in that all plants classified as such are
related through and evolved from a common ancestor, there probably isn't a
real group which could be called "dicots", at least not one which includes
ALL of the plants which are NOT monocots.

Go to The Flowering Plant Gateway at
http://www.csdl.tamu.edu/FLORA/newgate/cronang.htm to get some idea of the
diversity of opinion which has and continues to exist in this area. The most
recent work can be found under the section "APG". Compare the APG ordinal
classification (which is really just a work in progress at this point in
time) with the Cronquist scheme. Cronquist devised a classification scheme
which appears neat, elegant, and may be easily memorized - hence (probably)
its popularity and widespread acceptance by so many people over the past 20
odd years. But how "true" is it? The APG work, on the other hand, has many
"hanging chads" which indicate that it still very much a "work in progress"
and still subject to considerable revision. But because of its more
expansive base (DNA + morphology), it is probably closer to reality than any
scheme which was based upon morphology alone.

Nature is much more diverse than was initially suspected. She has taken many
twists and turns over the ages and unrelated plants have quite often
developed morphologically similar strategies to cope with different
evolutionary pressures. Combining DNA analysis with morphological comparison
is getting scientists closer to "the truth" but there is much more work
which needs to be done before we can realistically say that "the fat lady
has sung her song".

During this search for the truth, it is quite common to see plants get moved
from one area of the "classification scheme" to another as scientists
realize that what they thought were related groups are not in fact related
at all. Complicating this is the fact that "opinion" still plays a part, and
people being people, they generally resist change - if a botanist was always
taught and thought that groups "A" and "B" were related, it is sometimes
difficult to get them to accept that "B" might be more properly grouped in
with "C", based on an analysis of the DNA of all three groups.

Circumspection of the groups is also always evolving - i.e. the "boundaries"
that botanists draw around a set of morphological characteristics which
define a group. Some botanists are considered "lumpers" while others are
considered "splitters". As an example, consider the Lily family (Liliaceae).
Arthur Cronquist, one of the most influential botanists of the latter part
of the 20th Century (until quite recently, most university botany courses
were anchored upon his classification scheme, and much recent work still
uses "Cronquist" as the basis for their classification), used a very broad
brush when he defined what plants fall into the family Liliaceae. There are
85 listed synonyms for Liliaceae, many of which are valid names used for
sub-groups which other botanists consider distinct enough to deserve
independent "family" status on their own, separate from Liliaceae. It all
depends upon where they draw the boundaries (i.e. the circumspection) of the
larger group, and thus what is necessary to be considered "in" or "out" of
the group. Is a Tulip closely enough related to an Amaryllis for the two to
be included within the family Liliaceae? Cronquist thought so, but many
botanists both before and since have disagreed. You can find the same kind
of disagreement in many other areas of the plant family - it is an evolving
discipline with opinions changing as new information gets discovered.

The only way you can hope to get through these sorts of things is to
understand the reference (i.e. the authority) you are using and to find out
which reference someone else is using as a base. If you both use Cronquist,
all is well and you can communicate easily. If however you use Cronquist and
someone else is relying on some other "expert", you had better be aware of
any differences of opinion which exist between the two systems, or you'll
never understand one another.

Nomenclature deals strictly with the NAMES of the plants - it is a set of
"rules" which govern how a plant gets a name, keeps a name, and how that
name can be changed, when necessary. The other day, in my remarks to David
Grim concerning his Sagittaria plants, I was discussing the NOMENCLATURE,
not the taxonomy. Names are either valid or not, quite independently of the
issue of whether or not the name is applied to the correct plant by a vendor
or a hobbyist. Without actually seeing the plant David Grim has, as well as
having examples of ALL the other species of Sagittaria currently known,
described and accepted available for comparison, nobody can really say for
sure WHAT his plant is. It was sold to him as Sagittaria chilensis. I
checked out the validity of the NAME, and discovered a number of interesting
possibilities. But that is only about the NAME, not about the actual
specimens he has. If he's lucky, the vendor was accurate.

When a new plant is discovered, specimens are collected and examined,
hopefully by an expert, who determines where they fit into a "taxonomy" -
i.e. which previously known group of plants is this "new" one most likely to
be related to. Once this determination has been made, the plant can get a
"name". The genus is the group of plants most similar to the new discovery
and usually a careful worker can at least get this part right. But when
determining the species level distinctions, the person doing the examining
and the naming had better be familiar with ALL of the other species and
varieties of that particular group before he or she decides that the plant
in question is "new" or not. If they make a mistake, and people being people
that does happen, a name might be assigned, the description might get
published and the error might not be discovered for years, until a more
careful worker, more familiar with the entire group, sorts out the mess.

As I showed (hopefully) in my response to David, having the NAME of a plant
is like having a key to its literature. With the name, you can find out by
whom and when it was first discovered and described, possibly locate actual
herbarium specimens, maybe find out other interesting details associated
with how other botanists felt about it. Names can change, but if you dig
deep enough you can always follow the trail of those changes because the
rules of NOMENCLATURE require that certain procedures must always be

We can see that with the situation surrounding the genus Echinodorus, the
Sword plants. As Reue Jez pointed out in his article in the latest TAG, Dr.
Karl Rataj (the author of that infamous TFH book "Aquarium Plants") reviewed
the genus in 1975 and he considered it to contain 74 separate "species". A
later review, by other workers, considers the genus to contain only 26
genuinely separate species. Kasselmann soundly criticizes BOTH arrangements
and has published her own views in a recent German language book on the
genus. Whom do you believe? Who is correct?

Who cares, really??? A lot of this is way beyond us mere mortals...most of
us just want to know how to grow the things. But where we should care about
names is when we try to communicate with one another about our plants, or
when we are trying to obtain information about our plants. I understand the
difficulties many people have with scientific names and the comfort factor
associated with "common names", but in a group which comes from all over the
world and contains people who come from many different backgrounds, I find
it rather selfish of anyone to insist on always using "common names" or
anyone with an ego big enough to dare coin a "new" name for a plant which
more than likely already has a perfectly good and valid name, if only the
person had the wherewithal to actually do some searching to find out what it
is. The same goes for the use of "local" names in an international forum,
unless both the local name and the alternative and usually more generally
accepted name is always given. It all boils down to effective communication
and is an attempt to ensure that everyone knows what is being discussed.

Plants can and do get named in honor of people or places or things, and that
is perfectly O.K., and the use of such a name is fine as well so long as
EVERYBODY in your audience understands what you are referring to. As an
example, none of us yet knows the exact scientific name of the latest fad
plant, Christmas Moss. It might be a species of Fontinalis or it might be a
member of Vesicularia or it might belong to another genus entirely - mosses
can be very difficult to identify. But we can all agree on the facts that it
is both different from and in many ways nicer than the more common Java
Moss, and it can usually be differentiated from that plant by sight. And by
now, thanks to the sterling efforts and generosity of one list member in
particular, this little gem is widely distributed within the membership of
this group. So for us to use the name "Christmas Moss" when referring to
this plant here is fine, because we all know exactly WHICH plant is under
discussion. But what happens if you try to describe the plant to someone NOT
in this group and not familiar with the "story" of how it got that name -
remember that included with that story was the tidbit that it had been known
previously as "Triangle Moss", due to the structure of the fronds. What if
you are trying to describe the plant to someone who has never seen a
Christmas Tree (if such a person exists)? Communication can break down. So
long as you are careful to consider the frame of reference of your audience,
you can use any name you all like, nobody will care because everyone will
understand what you are talking about.

The more I learn about plants, their names and their classification, the
more I discover how little I really know and how uncertain all of this
really is, at least at this point in time.

James Purchase