Cultivars can have many origins. They can be selected from hybrids, a
mutation of a species, chimeral variegates, etc. In current usage, variety
and form are botanical categories.

The valid naming of each follow a different set of rules.

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

http://www.ishs.org/sci/icracpco.htm

In the case Caryopteris x clandonensis 'Heavenly Blue', 'Heavenly Blue' is
a named cultivar selected from the interspecific hybrid Caryopteris x
clandonensis. It is only one of several named cultivars of the popular
hybrid shrub available in the trade.

Caryopteris x clandonensis is a garden hybrid between Caryopteris incana and
Caryopteris mongholica.


"Duncan" wrote in message
...
On Thu, 20 Oct 2005 18:10:26 +0200, "P van Rijckevorsel"
wrote:

"Duncan" schreef
For no other reason than it interests me I'm trying to get my head
around the way plants are named.

Your example of Ajuga reptans 'Burgundy Glow' is an example of a
cultivar. As to the origin of the cultivar--natural, bred up, or
purely
illusory and for profit, one can't know without some research...

***
Note that it is no longer allowed to use "cv."
so it is Ajuga reptans 'Burgundy Glow'
(never Ajuga reptans cv. Burgundy Glow)
* * *

Why do some people write Caryopteris x clandonensis ?

***
A multiplication sign before an epithet indicates a hybridname. If a
multiplication sign is not available (for example in e-mail) a small
letter
"x" is used. People may vary in their opinion if something is a hybrid,
and
not all hybrids necessarily get a hybrid name.

PvR

OK ... I think ... so If a plant is named Caryopteris x clandonensis
'Heavenly Blue' I guess it means that someone thinks that 'Heavenly
Blue' is a hybrid between two plants of the species clandonensis.
Whereas if it was Caryopteris 'Heavenly Blue' then someone thinks that
it is a hybrid of several species of Caryopteris ...

Cheers
Duncan