No need for anyone to apologize for a slip - I do it all the time -
for me it comes from writing in the middle of the night after a long day at
work. As for 'Lady Emma', calling it an IB brought out an interesting
There are lots of good discussions about chromosomes and the results of
crossing various classes and/or species with differing numbers. I think
the 'World of Iris' has some good discussions on the basics. Again I am
away from my resources, so I still can't look up 'Lady Emma', nor cite
Anyway, here is a bit of an "in a nut shell" summary, that I hope makes
The IB class is mostly derived from crosses between 40 chromosome species
or dwarf cultivars with 48 chromosome TB species or cultivars, yielding 44
chromosome (give or take one or two) IB offspring. The old IB cultivars
are mostly derived from I. lutescens crossed with 48 chromosome TB species or
cultivars, and certain hybridizers such as Sass and others made bunches of
these. Newer ones tend to be from TB cultivars crossed with SDB cultivars
in search of desirable character combinations from the two parental
classes. Of course they are all interfertile, so they are crossed
with one another too.
Some of the 40 chromosome dwarfs (I know the plural of dwarf is dwarves,
but it sounds wrong for Iris somehow) are hybrids of 32 chromosome dwarf species
or cultivars with 48 chromosome TB species or cultivars, and I. lutescens and
other wild 40 chromosome species of bearded Iris also probably derived
originally from 32 chromosome species crossed with 48 chromosome species.
This is overly simplified, as 18 and 24 chromsome species (diploids) may have
been involved too - through unreduced gametes.
Anyway it sort of works out like this:
(32/2) + (48/2) = 40 This lead to wild species such as I. lutescens
and most cultivated SDB's (which are fertile with species such as I.
As for wild candidates there are a lot, but potential examples could
be as follows. It is likely that the parent species of the original wild
40 chromosome species were those that occur around or near the Mediterranean,
but things to move around over time. It seems that more notherly or
inland small or smallish 24 and 48 chromosome species such as I.
aphylla, I. croatica, I. junoniana, I. reichenbachii, I. suaveolens, and their
kin. probably weren't involved. Probably not I. variegata either, though
perhaps. Also, these (except for I. variegata, which was important) mostly
weren't involved in early cultivars either, but they are more and more
I. attica (unreduced = 16) + I. pallida (unreduced = 24) = 40
I. pumila (normally reduced 16) + I. cypriana (normally reduced 24) =
These could be examples of how wild species such as I. lutescens came to
be. They are fertile, because they have two sets of 8 and two sets of 12,
which act as if they are two sets of 20 (everything is ballanced). They
are technically tetraploids, but functionally they are diploids. This is
one way that chromosome numbers can be instantly and greatly increased through
addition of unlike sets to form new sets.
These tend to be dwarf (mostly SDB), but not as dwarf as the parent species
(mostly MDB) with a base set of 8 chromosomes (the 16 and 32 chromosome
When you cross the 40 chromosome plants with 48 chromosome plants, you get
an unbalanced set of one 8 and three 12's (usually - sometimes it doesn't
all sort out quite right and you get 43 or 45, or even occasionally numbers
futher away from 44, all the way from 40 to 48, because sometimes things don't
sort out quite as neatly as you might expect). Anyway, these usually end
up with 8 + 12 + 12 + 12 = 44, and they are usually intermediate to SDB and TB,
yielding mostly IB plants. The wild "species" I. germanica, I. albicans,
I. florentina, etc. are of this sort of ancestry as well. They tend to be
infertile (they will make some seeds), and due to their most common ancestries
they tend to be early flowering.
The MTB's tend to fall nearly all into two broad categories. One is
the diploids (nearly 100% of older cultivars) derived mostly from I. variegata
and I. pallida cengialtii, with a bit of other smallish diploid species such as
I. reichenbachii mixed in occasionally. They tend to be late-flowering
with more delicately proportioned stems and flowers than the 44 chromosome
class of (mostly) IB's, and they also tend to have morphological traits
dominated by I. variegata, while the 44 chromosome class mostly look
morphologically most like I. germanica or I. albicans (ignore the flower
The other mostly recent MTB group is very different and is derived from
cultivars of 48 chromosome TB's and BB's (BB's are usually genetically TB's, but
they just don't get as tall), crossed with small northern 48 chromosome species
such as I. aphylla, or cultivars derived from them. They tend to inherit
an earlier bloom time from the small species and some flower almost as early as
the 44 chromosome group, and often much earlier than most of the diploid
All the AIS categories tend to follow basic genetic groupings, and so MTB's
tend to be mostly 18 or 36 chromosome plants. SDB's tend to be mostly 40
chromosome plants. IB's mostly 44 chromosome plants of recuced fertility,
and TB's tend to be 24 or 48 chromosome plants. There are a number of
dwarves that are 24 or 48 chromosome plants, but they tend to be mostly wild
northern species or species crosses, and not to be too much involved in
hybridization of cultivars (yet).
The MTB's are mostly 24 chromosome plants close to I. variegata, but now
there is a second group of them that are 48 chromosome plants of a different
TB's (and BB's) are mostly 48 chromosome plants of Mediterranean / Near
Eastern species often with I. variegata and/or I. pallida ancestry. But
many old ones (usually smaller) are 24 chromosome plants, closely akin to the
MTB diploids, but usually with as much or more I. pallida than I. variegata in
The problem with the AIS system is that it only uses measurements as a
guide, and plants are inherently variable. So, sometimes a 44 chromosome
plant that would logically be an IB by genetics, will be a MTB or SDB by
measurement. So, they get classed with plants that are not similar in
chromosome make up. The same with 40 chromosome plants. Even though
they are genetically most like most SDB's, they can be larger or smaller than
average, and become MDB or IB by AIS registration.
As the years go by, the ancestries get more and more mixed up, muddled, and
genes blended together in new combinations. However, it is very difficult
to get the chromosomes of the base 8 species into plants with base 12 chromosome
numbers and visa versa, because once they are mixed, they don't tend to cross
back to either main parental group very easily. The 40 chromosome
intermediates are fertile, but in effect they are isolated from either parental
group by their new chromosome make-up. When they are crossed with the
parental groups in either direction they tend to yield sterile plants with +/-44
chromosomes or +/-36 chromosomes.
The 36 chromosome class doesn't seem to be well-developed, but they should
be mostly MDB plants, and I'm sure there are a lot of them out there that just
haven't been recognized as such yet. They may even be some of those
"problem" parents that don't make fruit or pollen well, for "unexplained"
reasons. These would mostly come from a cross of (32/2 = 16) +
(40/2 = 20) = 36.
The more backcrosses are tried, the more will be successful, and the more
the chromosomes will get recombined in cultivars eventually. Some day
there may be MDB with 32 chromosomes, but with genes from TB's and
visa-versa. Also, the more new species are added to the mix, the more
complicated, mixed up, and interesting the cultivars will become.
And this doesn't even consider any of the Psammiris, Regalias, Arils, etc.,
which can and are gradually being added to the mix too.
----- Original Message -----
Sent: Sunday, October 09, 2005 9:18
Subject: Re: [iris-photos] RE: OT: ID a
Tree & rebloom news
Excuse me for interrupting, but
all this info is just making my head swim. I have great interest
understanding the affects of the chromosome counts and hope to educate myself
to help me to cross more effectively. Can you suggest any reading
material to help me with this? Thanks much
Lascassas that is::::::: :)
Just to be a bit of a rebel here.
'Lady Emma' resides
with the old IB's in my beds, where it fits in quite
Regardless of registration, I consider 'Lady Emma' to be an
IB, but my definition does not restrict itself to only measurements of stalk
and flower, and I am more concerned with the plants than what the lists say.
I don't remember the chromosome count of 'Lady Emma', but I believe it
is of the 44 (or close) type of ancestry and it's behavior (early flowering,
reblooming) and morphology are not like the older diploid MTB's. It
flowers a full month to even six weeks before the diploid MTB's here.
The newer tetraploid MTB's (different ancestry) may have a similar
calendar to 'Lady Emma' (but still not quite as early), but they are quite
I know that 'Lady Emma' appears in most lists
(including the AIS check list?) as an MTB, and so will continue to appear in
sales lists and shows as an MTB.
I don't have my AIS checklists, the
chromosome count, nor the parentage of 'Lady Emma' handy; so, these comments
have the uncertainty of being from memory too.
Please correct me if
any of this is wrong.
----- Original Message -----
From: Laurie Frazer
Sent: Sunday, October 09, 2005 8:07
Subject: Re: [iris-photos] RE: OT: ID a Tree & rebloom
On Oct 6, 2005, at 10:30 PM, email@example.com
The only rebloom I have had is LADY EMMA , a yellow IB
with 4 stalks blooming. I want more!!!!! I will keep an eye out
for ROSILIE FIGGE. She bloomed this Spring for the first time. I
also want bloom on DAUGHTER OF STARS , BABY BLESSED
Just to help you keep your records
straight, Annette, LADY EMMA is an MTB, and BABY BLESSED is an
I sure wish I could enjoy rebloom up here, but it's
rare, indeed, that any iris can manage such a feat here in zone
zone 3b, AHS zone 4 - northern Minnesota
slightly acid, potassium deficient, clay