Peony taxonomy - boring.

James Waddick
Thu, 05 May 2011 06:39:30 PDT
>Here's a question for the peony experts: do the Itoh interdivisional 
>hybrids ever form short, above ground woody growths?

Dear PBSers,

	Jim McK's questions is a more interesting question than might 
appear to most.

	The word 'Interdivisional' is very generic, both odd and 
appropriate. Any taxonomic division except the very lowest can be 
divided into lower "divisions" such as Family to Genus or Order to 
Family and so on. The taxonomist will often divide some taxonomic 
level into less severe divisions such of subfamily, subgenus etc., 
The taxonomic categories include order, family, genus and species. 
There is no taxonomic level called a division.

	The genus Paeonia has three 'fairly obvious' divisions: Most 
herbaceous species from Europe and Asia (with a small dip into  N. 
Africa). the woody or 'tree" peonies and the isolated peonies of 
Western North America. Over the years the genus has been divided into 
three subgenera or into three sections. The term 'section' may be new 
to some, but it is taxonomic division between genus and species, but 
is little used today. It takes some precedent when there are major 
divisions between the subgeneric divisions and there are very 
distinct species within a subgenus. Generally not very common these 

	Yet if you were to look at most of the modern reviews of 
peony taxonomy, you see that the genus is often divided into 3 
sections in the genus. The one exception is "The Genus Paeonia" by 
Halda & Waddick (Timber Press, 2004) where the genus is divided into 
what I consider more sensible subgenera.  All this is appropriate to 
Jim McK's sentence because some striking hybrids have been developed 
between these major divisions in the genus starting with a Mr Itoh in 
Japan. These quickly became known as 'Itoh Hybrids" and then more 
generically as 'Intersectional hybrids'. The former term has been 
firmly attached by the American Peony Society to those intrageneric 
hybrids involving the species used by Mr Itoh. Some newer hybrids 
have involved other species and even other divisions of the genus. So 
the term "Intersectional" really covers all such hybrids not only 
those original Itoh hybrids, but all newer wider hybrids.

	But if the proper division of the genus is into subgenera, 
these hybrid are more properly intersubgeneric hybrids. Needles to 
say it is easier for most people to call them all 'Itohs", but 
"Intersectionals' is more appropriate even if taxonomically suspect, 
while "Intersubgeneric" probably confers the most appropriate title, 
but is very ungainly.

	These intersectional hybrids (I'll use the term most often 
seen in horticultural circles) combine characters of both woody and 
herbaceous species. Some of these produce short above ground 
semi-woody stems that can retain viable looking winter buds above 
ground  just as Jim McK describes. Herbaceous peonies NEVER do this 
and tree peonies do this continuously with woody stems growing longer 
and persisting for years.

	Although I have yet to see a scientific study of these above 
ground stems, it seems to me from casual observation that most of the 
time that buds on these above ground stems fail to develop. I think 
this is due to the incompletely woody development of of these stems. 
The buds may be hardy enough to 'survive, but lack the hardiness of a 
true viable woody stems.

	In my garden I have seen these 'woody appearing' stems get to 
six inches or more and have 3 or 4 dormant buds, but never had true 
woody stem with viable dormant buds that developed in spring into new 

	In milder climates, do these these dormant buds ever develop 
at all (Tony ?).

	And ....., today most of these original Itoh hybrids (there 
were four of them originally brought to the US and registered) are 
little grown. Modern intersectional hybrids are much  improved over 
these old Itohs. Personally I would not recommend them except to 
collectors for their historical interest.

	As an aside, years ago I helped establish a local peony 
society ( and we hold a big peony sale every second 
fall. This year we have named 'The Year of the Intersectional Peony' 
and we will have over 100 plants of 24 or so named intersectional 
hybrids including some of the newest cutting edge cvs.  None of the 
original Itohs are in the sale.

	That was convoluted.		best		Jim W.
Dr. James W. Waddick
8871 NW Brostrom Rd.
Kansas City Missouri 64152-2711
Ph.    816-746-1949
Zone 5 Record low -23F
	Summer 100F +

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