Peony taxonomy - boring.

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
days.

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
growth.

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 ( peonies.com) 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
USA
Ph. 816-746-1949
Zone 5 Record low -23F
Summer 100F +