Rhododendron 'Ponticum Roseum'

Suggestions for a complementary quote, a word that these mandala images evoke, or some history or other information about the flower itself are most welcome, as are corrections to my flower identification if I've got it wrong and any other comments you'd care to make.

I'd also appreciate identification of the specific cultivar, if applicable.

Thanks,
- David
© 2005, David J. Bookbinder

 

The plant name is probably supposed to be 'Roseum Elegans' or one of the other old hybrids with 'Roseum' as part of the name.

 

It could be the Hybrid Ponticum Roseum ... I see nothing to doubt that except that it looks like it is going to be a tighter ball truss. Frankly, there isn't enough to positively identify as you need at least a opened flower with throat visable, good example of the truss, and one of beter more leafs. And its a common color (looks to be lavendar when opened) ... there is often such slight differences ... and pictures can be misleading ... all making positive identifycation hard. Roseum Elegans is, however, very common and thus a very good guess. English Roseum is also very common, but my guess is that it isn't.

 

OK, I do see it listed here. Others are calling it Rhododendron ponticum 'Roseum', but if everyone is talking about this same hybrid of R. ponticum and R. maximum it certainly shouldn't be listed as a cultivar of R. ponticum alone.

http://www.rhododendron.org/descriptionH_new.asp?ID=901

 

Well, apearantly this has been a discussion here befor and I assume I'm missing some posts. I agree Ron, but I'm sure there is plenty to debate. First there is the RHS (IRA for genus Rhododendron) which list as R. ponticum 'Roseum'

http://www.rhs.org.uk/Databases/HortDatabase.asp?ID=137816

Not to add to the confusion, there is also the synomym 'Maximum Roseum' (not maximum 'Roseum' ) as I'm guessing you were refering to with your Maximum reference? Considering this is an early hybrid, hence the latin, and it has been around for a such a long time, I was suprised RHS came up listing it as R. ponticum 'Roseum' I'm now wondering when that came about ... name changes do occure and I might guess that it occured in 2002, but I am a little baffled.

With some DNA testing, R. ponticum 'Roseum' may prove to be correct, and I don't doubt that, but as a long accepted hybrid/cross, the name clearly seems invalid. I guess I wouldn't rule out a typo or glitch here either. Perhaps the bottom line is the "rules", RHS is official name, so technically its R. ponticum 'Roseum'.

Naming has been an age old issue with Rhododendrons (I'm sure other plants too) and I don't expect it to end in my lifetime. Thanks for the heads up...

 

The ARS site I linked to is where the 2 species hybrid parentage is given. The RHS' determinations are far from flawless, same as elsewhere, so you can quit being surprised. Knowledge is an ongoing process, at all levels.

 

I'm not suprised by the ARS site at all. However, R. 'Ponticum Roseum', sym R. 'Maximum Roseum' has been accepted as R. ponticum X R. maximum for nearly a hundred years. Reclassifying occures all the time, true, and the entire Rhododendrum tree was reorganized so thats no suprised. My surprise is it now varity/cultivar R. ponticum 'Roseum' vice a valid hybrid, hence, there was some evidence it wasn't a cross.

Of course, I did check the ARS site, and I checked RHS site, and I did an internet search, and I also cross checked back to David Leach's 'Rhododendrons of the World'. Yes its cir 1961 and is out dated, however, he was the leading expert at the time and the book provides the most comprensive list for that time, hence it is a historical reference. And yes it was noted R. 'Ponticum Roseum' as R. ponticum X R. maximum then.

 

Is it a R. ponticum to begin with? I have my doubts, as R. ponticum, rated as being hardy down to -25°C (-15°F) is probably not hardy enough for the Massachusetts area. Records show frost damage to this species in Seattle, WA, in 1955.

As for varieties of R. ponticum in cultivation, according to Elizabeth Carlhian: album, baeticum, cheiranthifolium, lancifolium, and variegatum. It is interesting to note Ms. Carlhian does not mention var. roseum whereas the Sally & John Perkins photograph accompanying the article claims to be just that!

I am acquainted with the white and variegated forms, so var. album and var. variegatum would appear to be valid names. The RHS Rhododendron Handbook, 1980, states var. cheiranthifolium may be of hybrid origin. I was unable to verify the validity of the other varietal names.
Peter A. Cox & Kenneth N.E. Cox, in The Encyclopedia of Rhododendron Species, 1997, refer to several cultivars of this species, but do not specifically mention any by name.

Homer E. Sally and Harold E. Greer, in Rhododendron Hybrids, Second Edition, 1992, list R. 'Ponticum Roseum', synonymous with R. 'Maximum Roseum'. It is a valid (registered) name.

So, R. 'Ponticum Roseum' exists, but whether R. ponticum var. roseum (or R. ponticum 'Roseum') officially exists, is open to debate.

 

Although the H.H. Davidian classification has in general been rejected, his 4-volume survey of 'The Rhododendron Species' contains a lot of useful information.

In 'Volume III, Elepidotes continued', 1992, Davidian lists the following: R. ponticum Linn. and R. ponticum Linn var. album Sweet.
Reference is also made to 'forms that appeared either as sports or hybrids': 'Aucubifolium', 'Cheiranthifolium', 'Folius Purpureus', 'Lancifolium' (nomen illegit), and 'Variegatum'.

Herb Spady's Rhododendron Species Dictionary makes no mention of R. ponticum var. roseum (or R. ponticum 'Roseum') either.

So, based on all information available to me, it appears that album is the only valid R. ponticum cultivar name.

Positive identification of a rhododendron from a picture is, as has been suggested, difficult. If the flowers were fully opened, you would have a better chance at getting a positive ID, but given the state of the truss, a positive ID is probably impossible.

 

Excelient posts! A search on the RHS plantfinder with keword Ponticum yeilds:

ponticum 'Aureomarginatum'
ponticum 'Cheiranthifolium'
ponticum 'Foliis Purpureis'
ponticum 'Roseum' <-- the issue!
ponticum 'Silver Edge'
ponticum 'Variegatum'

The RHS is the 'official' register of Rhododendron names, and considering their strict naming ... the real question is where/how did they come up with R. ponticum 'Roseum' and why not R. ' Ponticum Roseum' ... I'm asking them....

 

A sleuthing friend turned up the following (thanks 'Mike'):

"1.The Species of Rhododendrons - second edition edited by J.B. Stevenson (of Tower Court fame) 1930
He mentions that there are several garden 'forms' but does not specify a 'roseum'
2. Rhododendrons and Azaleas - 2nd edition Clement Gray Bowers 1960 - He also mentions that several varieties have been described (including variegata) but does not speak of 'roseum'
3. Rhododendrons,Azaleas,Magnolias, Camellias and Ornamental Cherries - A. T. Johnson - 1948 - no mention
4. The Handbook of Rhododendrons - compiled by The Arboretum Foundation of Seattle Washington 1946 - nothing
5. Rhododendrons and Azaleas - William Watson Present Day Gardening Series - could find no date but prior to 1911 - speaks of "numerous varieties" but does not specify
6. The Rhododendron "American Plants" 4th edition Edward Sprague Band Jr. 1876 - mentions a very large number of varieties - including a variety roseum."

I asked Jay W. Murray, North American Registrar of Plant Names:

"The plant is a hybrid, not a species. The proper name is R. 'Ponticum Roseum', and a common synonym is R. 'Maximum Roseum'. The hybridizer is unknown, but it is believed to be a cross between R. ponticum and R. maximum. It is known to have been distributed in eastern Pennsylvania earlier than 1954."

So we have one reference to 'Roseum' dating back to 1876 but since all attempts at verification failed, I submit R. ponticum var. roseum (or R. ponticum 'Roseum') is probably not a valid name.

 

You guys are having too much fun as from my end I
am enjoying this discussion. It is unique how semantics
can either work for us or against us.

OK, I do see it listed here. Others are calling it Rhododendron
ponticum 'Roseum', but if everyone is talking about this same
hybrid of R. ponticum and R. maximum it certainly shouldn't be
listed as a cultivar of R. ponticum alone.

I agree with that premise. If the plant is a bona fide hybrid
as agreed upon by committee, even if not fully proven, it
should not be listed as a cultivar of R. ponticum.

"The plant is a hybrid, not a species. The proper name is
R. 'Ponticum Roseum', and a common synonym is R. 'Maximum
Roseum'. The hybridizer is unknown, but it is believed to be a
cross between R. ponticum and R. maximum. It is known to have
been distributed in eastern Pennsylvania earlier than 1954."

Let me give you guys a scenario that bothered us in Magnolias
but we could not argue with the foundation either. Let's say
that from some emasculation that a hybrid of two species
came about. Regardless of whether the technique was done
right or that wind or an insect may have done the actual
pollinating. We saw ( I saw them in New Zealand) with some
hybrid Magnolias back in the late 80's, early 90's some new
names come about that we had interest in such as ‘Athene’,
‘Apollo’, ‘Star Wars’, ‘Serene’, later ‘Atlas’ and ‘Vulcan’.
Whether or not we felt these Magnolias were true hybrids
or not soon became immaterial as the person that selected
out these Magnolias knew which was the seed parent in each
case. Essentially what we had was the cross breeding of
pollen donor parents vs. seed bearing parents in which both
parents yielded a different offspring. In one case Magnolia
a was crossed onto Magnolia b which yielded Magnolia a x b.
The other cross of Magnolia b crossed onto Magnolia a yielded
Magnolia b x a. Those offspring, what we call sister seedlings,
were selected out, grown on and in turn named.

In this case we do not know what the seed bearing parent
was whether it was R. ponticum or R. maximum. Would
not the same premise above hold true for the offspring
depending on which parent was the seed parent? In other
words that R. ponticum crossed onto R. maximum would
yield a hybrid R. ponticum x R. maximum whereas if we
also crossed R. maximum onto R. ponticum can we expect
that cross to yield the same hybrid (R. maximum x R.
ponticum) as the former cross yielded? DNA testing may
not tell us all that we need to know to separate out which
one had the R. ponticum as the seed parent and which one
had the R. maximum as the seed parent. So based on DNA
analysis we are likely to come up empty on this one as we
have no definite proof that a hybrid has indeed come about
through breeding or through natural selection. We are
speculating that R. Ponticum 'Roseum' is indeed a hybrid
in the first place but more importantly we do not know
which parent was the seed bearing parent so, with all that
in mind it can be acceptable to call what several people
feel is a hybrid a cultivar instead as the significant details
of the parentage cannot be proven. Thus, there is enough
doubt to suggest that this plant is not a hybrid at all giving
rise to the usage of the R. 'Ponticum Roseum' name but at
the same time refuting validity of the synonym name of
R. 'Maximum Roseum'. The plant can be called one or the
other but not both.

If there is agreement that this plant is indeed a hybrid
then it cannot be a cultivar of R. ponticum nor can it
be a cultivar of R. maximum. It is, as universally
agreed upon, a hybrid and is technically a known
cultivar of neither Rhododendron. Ron is right on
the mark.

Jim

 

Jim,

>> We are speculating that R. Ponticum 'Roseum' is indeed a hybrid <<

following convention,
1. a plant named R. Ponticum 'Roseum' is misspelled.
2. R. 'Ponticum Roseum' is a hybrid.
3. R. ponticum 'Roseum' is not a valid registered name.

Where's the speculation?

 

Okay, you got me for my mistake with
the blasted ' marks. This is the one I was
writing about R. 'Ponticum Roseum'.

R. ponticum 'Roseum' is not a valid
registered name.

No arguments there.

The speculation lies in the fact that people are
calling this plant a hybrid when it in fact may
not be a hybrid at all. Who knows the genetics
of this plant? What foundation does anyone
have to call the plant a hybrid in the first place?
Just because this person or that person called
it a hybrid? Do we know it is a hybrid for sure?

Here is the problem as seen from an outsider
that no one likes anyway. The Rhododendron
people want this issue to work both ways.
One to call this plant a hybrid and the other
issue is to think of this plant as being a cultivar.
Well, if this plant is a hybrid then it cannot be
a cultivar. If this plant is a cultivar it cannot
be a true hybrid. The issue from the naming
suggests that people want this plant to be both
for them and it surely cannot be, even by
conventional thought. We are into theory now
but in practice there are some holes in this
naming as suggested by Ron B and fourd.
All that really matters is when I go to Greer's
and buy this plant that it should be the same
plant I can buy at Klupengers' and that his
plant is the same one I can buy from a
nursery in Fort Bragg or from a nursery in
Pennsylvania.

If people cannot explain the genetics of what
they are seeing then the plant has to be a hybrid
right? From where I sit the answer can be wrong
more often than we are correct. I think there is
still the possibility that R. 'Ponticum Roseum'
could be a form of R. ponticum instead rather
than a bona fide hybrid between R. ponticum
and R. maximum, otherwise this plant would
be written out similar to this R. x ponticum
'Roseum' or R. x maximum 'Roseum' if we
feel we have to include the "roseum". Even
still, even if the plant is a hybrid, the name
of R. 'Ponticum Roseum' becomes absurd,
no matter what the formal registration name
of this plant may be. I agree if this plant is
a definite hybrid it should be written out as
R. ponticum X R. maximum and drop the
"roseum" unless there are other individuals
from the same crosses that are also named
and we choose the "roseum" to denote it
different from the other siblings.

Jim

 

Well, it was a little slow in comming but I did get a reply from RHS on this ... and as promised am posting it ...

<Quote>
The International Rhododendron Register lists the use of both 'Ponticum Roseum' and ponticum 'Roseum'. Both are uses long established: ponticum 'Roseum' from a Loddiges listing of 1818 the 'Ponticum Roseum' being taken up in the 2004 Register from the entry in the first edition of 1958 but I suspect of much earlier origin than that. It is possible that they refer to the same plant but we do not know this for certain. The use of 'Ponticum Roseum' seems to be definitely associated with a plant thought to be a ponticum x maximum derivative and is I suspect the plant most widely cultivated. I would recommend that if this hybrid origin plant is what you have cultivated then you should use 'Ponticum Roseum' to label it. The inclusion of Ponticum in the epithet 'Ponticum Roseum' is confusing for several reasons but since it seems to be long established I thought it best to leave well alone especially as we do not know for sure how it relates to ponticum 'Roseum'.If it was considered necessary a name change could be considered at some time in the future but sometimes this can lead to more confusion! There is a close parallel with several "Catawbiense" cultivars of similar format with a similar hybrid origin.

As far as the other cultivars you mention are concerned I see that the Register suggests that they are all listed as ponticum selections with the proviso in a couple of cases that they could be hybrids of this species. It is possible that the true origin of all these cultivars needs examination but the current listing reflects what I think has been common practice. If good evidence can be provided to substantiate a change then we will make a change.

Getting the Register and the Plant Finder completely in unison with respect to rhodo names is a job high on my list of priorities. There is not a lot where they differ and what there is is the result of two teams of people working on the different projects and sometimes with different views about how to solve nomenclatural and taxonomic problems. We do our best to talk to each other but as you can imagine we can not always follow up every query that comes to light.The Plant Finder certainly has an immense amount of time and effort expended on getting the names right and we think is as reliable list as you will find but it is not perfect! You must bear in mind too that often the problem is not that the name is unacceptable just that it has been applied to the wrong plant!

Do let me know if I can be of further help

yours sincerely

Alan Leslie

<end quote>