Dang Dave; you're an encyclopedia. You have just added greatly
to the
iris research I have been doing for 10 years now. Of
coarse I have
concentrated more on the Arils and some of the
other rarer species and not
so much on hybrids.
John B
--- In iris-species@yahoogroups.com,
David Ferguson <manzano57@...> wrote:
>
>
> To expand
on Bob's explanation a bit.
>
>
>
> The majority of
wild bearded Iris species in Europe and western Asia (not including the Aril
and Regalia groups) have a base chromosome number of 12 (the number of one set
of chromosomes). Most of these are diploid (meaning they have a single pair of
sets with 24 total). This is the lowest number possible for most of this
group. Some (including I. croatica) are tetraploid and have 48). Most of the
tetraploids are from warmer/drier climates to the south of Europe and in the
Near East. Probably all of these with 12 as the base (haploid) number can be
crossed with one another rather easily, but the triploids produced when a
diploid is crossed with a tetraploid (with 36 chromosomes) tend to have
problems with that odd set when they try to reproduce, so tend to be sterile,
or only by chance occasionally produce gametes (ovules and pollen) that have a
proper number of chromosomes to pair up with that from other plants.
>
>
>
> The tetraploids mostly tend to resembe one another
and also I. x germanica, and most have been lumped by some under that name.
However, really there are several distinct looking populatoins within this
group, and each probably represents a good "real" naturally occuring species.
I croatica is one of these wild types, but with a few others such as I.
aphylla, it doesn't really fit into the I. germanica concept, even in the
broad lumped together sense. These "others", have a very different look about
them, and I would eliminate I. croatica from the I. x germanica discussion
right here.
>
>
>
> The taller/larger species of
these tetraploids (hard to say how many are truly distinct and how many are
regional variations of the same thing) look like the older Tall Bearded
cultivars, and along with Iris pallida and Iris variegata (both diploids) they
are the main ancestors of most of the BB and TB Iris cultivars that we now
grow. However, some breeders add genes from other wild species to the mix all
the time, and some of the classes (but more those smaller than BB and TB)
become more mixed every year. A few of the wild tetraploid types most
important in early breeding of Tall Bearded Iris include I. cypriana, I.
mesopotamica, I. trojana, and I. 'Amas' (= I. amasia, apparently an invalid
name, but I. varbossiana seems to be the same species, and the cultivar 'Amas'
should probably be I. varbossiana 'Amas').
>
>
>
>
There is also a group of wild bearded Irises that is different and has a base
chromosome number of 8. These are all dwarf species from basically near the
north coast of the Mediterranean, and they are the ancestors of most of our
"Miniature Dwarf" and "Standard Dwarf" Bearded cultivars. Those that are
diploid have 16 chromosomes, and those that are tetraploid have 32
chromosomes. Most cultivated MDB and many SDB Iris have 32 chromosomes and are
this ancestry.
>
>
>
> Now then, I. x germanica
(what is supposed to be the "true" germanica) has 44 chromosomes (give or take
one or two). This seems to be [12 + 12 + 12 + 8), and is derived from crossing
a 48 chromosome parent with a 32 chromosome parent to get a 40 chromosome
Standard Dwarf Bearded type thing with 40 chromosomes (which functions
basically as if it is diploid, but it basically has now combined two sets of 8
with two sets of 12 to get a two new (functioning as) haploid sets of 20, yet
there are still 4 sets present). There are a few wild reproducing populations
of Iris with 40 chromosomes, such as I. marsica, that are of this same
make-up. Apparently one of these hybrid "40's" back-crossed with a species
with 48 chrosomes (it seems to have happened several times to give us ancient
cultivars such as 'Albicans', 'Florentina', assorted "germanicas" and others).
It is not clear which parent species were involved (perhaps mostly I.
varbossiana types which grow in Turkey and nearby and I. pumila, which grows
mostly further west, or perhaps several species, or even perhaps different
species for different individual clones) , but it should be possible to figure
out by comparing DNA. Anyway, the resulting "44's" seem to be vigorous plants
that have been divided and spread around by humans for centuries, particularly
in the Mediterranean region, and seem to have been carried to the Americas (at
least South America) by the Spanish early on. These 44 chromosome hybrids
(functionally they are tetraploids with one mismatched set of chromsomes) can
reproduce, but because of that mismatch set of 8 in their makeup, the
chromosomes don't behave properly during meiosis, and the fertility seems low
when seeds are produced. Even so, most can make some fertile seeds (perhaps by
chance sorting, some seeds get the right mix of chromosomes to be viable), and
some of these have apparently added to the number of "clones" of the real
germanica type hybrids. There are wild populations of these too, mostly along
the north side of the Mediterranean, but in theory they are mostly made up of
relatively few individuals that have been moved around by humans and then
naturalized.
>
>
>
> Our Intermediate Bearded class
of cultivated bearded Iris mostly have a similar chromosome makeup, and most
are produced by crossing Tall Bearded Iris with Standard Dwarf Bearded, since
the 44(+/-) chromosome IB Iris also have reduced fertility. Some of the older
cultivars are dead ringers for I. x germanica, and cannot be distinguished
based on their structure. A few of these that were (or probably were) man-made
in relatively recent time include 'Golden Cateract', 'Crimson King', 'Eleanor
Roosevelt', 'Southland', and others like them. I. albicans is often not
associated with I. x germanica, but it is of this type too, as is I.
'Florentina', as well as all of the sports of these two.
>
>
>
>
>
> and so on.
>
>
>
> Dave Ferguson in New Mexico
>
>
>
> To: iris-species@yahoogroups.com
>
From: eleanore@...
> Date: Fri, 28 May 2010 09:49:19 -0500
>
Subject: Re: [iris-species] I croatica
>
>
>
>
>
> 
> Thanks for the explanation, Bob.
>
> A few years ago, I got the US version of I germanica from HIPS. It
didn't even survive it's first winter here. I croatica has formed a lovely
clump in it's 5 yrs here. I got it from Chuck, so maybe he can comment on
it.
>
> While I do know my median and dwarf iris very well, I
don't know all that much about species iris. I do love them all
though.
>
> I'm here to learn. :)
>
> El, near
Winnipeg, Manitoba, Canada Z3
> AIS Region 16
>
>
>
----- Original Message -----
> From: Robert Pries
> To: iris-species@yahoogroups.com
> Sent: Friday, May 28, 2010 9:36 AM
> Subject: Re:
[iris-species] I croatica
>
>
>
> While it is
certaibly true that Iris croatica belongs to a complex of species that have
been relegated to Iris germanica, it is not at all bad form to use the name
Iris croatica. Iris germanica and its allies have been very poorly studied.
Brian along with many western Botanist tend to be lumpers. But the splitters
have separated out a number of species. Iris germanica should be a bit of an
embarassment for any Iris taxonomist since although it is the type for the
genus, and yet it has been very very poorly defined and studied. What is
called germanica in the USA is a clone that is practically sterile and
triploid. It has been studied enough to believe it is a natural hybrid but the
parents have never been figured out. Iris croatica on the other hand blooms
later and is quite fertile. It is sad how much we really do not understand. I
do not think Brian or anyone else at this time would insist on croatica as
only a synonym, even if it is convenient to lump it with germanica.
>
>
> ----- Original Message -----
> From: "David Nicholson"
<d.avensis@...>
> To: iris-species@yahoogroups.com
>
Sent: Friday, May 28, 2010 8:03:14 AM GMT -05:00 US/Canada Eastern
>
Subject: Re: [iris-species] I croatica
>
>
>
>
Brian Mathew has Iris croatica as a synonym of Iris germanica.
>
> David Nicholson
> in Devon, UK. Zone 9b
>
> El
Hutchison wrote
> <Here's I croatica blooming today. That's one of my
raised iris nursery
> beds in the
background.>
>
