Since you appear to be genuinely interested in the valid naming of plant and
the rules that determine them, I refer you to the International Code of
Botanical Nomenclature.

http://www.bgbm.org/iapt/nomenclatur....Luistitle.htm

Typification is key to understanding what a particular plant and it ranking
really is.

When the genus Coleus was named, it was based solely upon a single species
named Coleus amboinicus which automatically becomes the type species. When
that species was transferred to Plectranthus, the genus Coleus automatically
went with it. Unfortunately the plant know as "Coleus" in the horticultural
trade is neither a true Coleus nor Plectranthus.

The choice of the type species is made by the author or selected very
carefully from the original species described in the genus. There is nothing
arbitrary about it. (Of course, there have been a few exceptions when the
choice of type by latter authors have been overturned because they were not
representative of the genus as originally defined.)

The presently accepted way of denoting plants families consists of the name
of the type genus together with the -aceae ending. Thus we have Asteraceae.
The genus Aster is the type genus for the family. The old Jussieu name
Compositae does not indicate the type genus or any other genus in the
family. Unfortunately many not familiar with plant taxonomy still use the
incorrect family names.

There is no way to enforce the use of the proper names. The ICBN does not
impose monetary penalties of jail time for those who do not comply with the
code. Most of the horticulturists, plant pathologists, biochemists and
master gardeners would be serving hard time if it could be done!!! Not to
mention the fourtune collected in fines!!!

Most horticultural "experts" still don't know the difference between a
botanical variety and a cultivar.

That the US congress insists upon coining common names for endangered
species is also laughable because most of the plants were never common
enough to get anything but botanical names. We probably should be calling
congressmen and senators by "common names" instead of using their proper
names too!! Will congressman "Prissy Fusspot" please step up to the podium?
There is a appropriations bill on the floor proposed by senator "Poopy
Pants". I get a second to that motion by senator "Fart Face". I guess nobody
explained it to them.


Andrew Ostrander wrote in message
...
Thank you for your reply. I've interspersed comments among your posting.

"Cereoid+10+" wrote in message
om...
Cultivar groups are not botanical taxa and they don't count.

I know they're not botanical but they may help one identify a plant more
precisely.

Common names mean nothing of value.

They help me, and maybe you, to recognize the plant faster.

Eustoma grandiflora being called Lisianthus (Lisianthus russelliana) is
because of a misidentification by the horticultural trade that
unfortunately
stuck. The flowers of Eustoma look nothing at all like those of
Lisianthus.
In the revision of the genus Lisianthus done many years ago, Eustoma
grandiflora was specifically excluded from the genus.

Too bad the horticultural trade won't change. I see though now that there
is a distinction between acceptable synonymous names and erroneous
horticultural ones.

The only valid conserved family names are those ending in -aceae. The
old
Jussieu family names are no longer used except by a few old die-hards
and
unenlightened horticulturists.

When I do internet searches, I find more than a few research publications
that use
the old names. For example, last week I looked for diseases of the
Asteraceae,
( my seedlings of this family all suffered from the same disease last
year,)
and the only thing I could find was long, detailed, scientific, and
referred
to Compositae,
not Asteraceae. As far as I can tell, botanical taxonomists don't
prohibit
use of the old names or even really encourage switching.

The genus Coleus is synonymous with Plectranthus. The type species for
the
genus Coleus is Plectranthus amboinicus.

?? I don't know what a type species is. Is that a species that is
representative
of the genus and by decision arbitrarily defines the genus?

The "Coleus" of the horticultural
trade is correctly named Solenostemon scutellarioides and is not at all
a
member of Plectranthus section Coleus in the proper botanical sense. The
species has many synonyms.

Again, I wish the trade would switch. But why should they when the trade
names seem more enduring than the botanical ones (humour), are better
known, and are a lot easier to say!

I sympathize with your trying to keep up with the Asteraceae. The
family
is
in the process of a major overhaul and many formerly large and amorphous
genera are being divided up into smaller more sharply defined genera.
Many
old species names are being reduced to synonymy also.

I appreciate your reply and your taking the time to respond, and thank you
again!

Andrew