Robt R Pries
Tue, 09 Mar 2004 09:13:30 PST
Dear All,

Somehow I have lost the file I had developed for introducing this Topic of 
the week so I will have to get started with a quickly cobbled together 
version. Since I have also had problems sending it I will send this as a 
repy to Mary Sue and see if it works

The topic of the week is Iris;

For those that may be relatively new to the genus let me point out a few 
terms that will be helpful. The flower of and Iris is quite unusual in that 
there are two cycles of Tepals (petals/sepals) that are commonly 
distinguished. The inner cycle is the standards which usually rise upwards 
as in Flags. The outer cycle is the falls which as the name implies hang 
downward. Everyone knows stamens when they see them but the female 
structures are petaloid style arms that overarch the stamens and have 
confused many a first time hybridizer. The stigma is a lip on the end of 
this style arm. This flower structure is unique to Iris and a few close 
relatives, Moraea, Dietes, etc.

The Genus offers around 200-250 species and most if not all are interesting 
garden plants. The traditional classification system provides us with 
various sections and series under the Genus but new DNA research has more 
or less turned on its head how these categories are organized. Only a 
preliminary report has been in publication but I will try to give a brief 
summary and then return to using Mathews classification since it is 
available to everyone and we can all be on the same page.

The old classification basically separated  the genus by winter storage 
organs, Roots, Stems(Rhizomes) and Bulbs. The largest of these groups, the 
Rhizomes, was divided into three groups those with beards, those without 
beards, and those with crests. These are structures on the falls which 
guide the pollinating bees into three pollen tubes each formed by a fall 
and a style arm. These tubes mean that each flower functions as three 
separate flowers. The bearded group is divided again into plants with 
arillate seeds and plants with seeds without arils.

The new classification will separate the beardless rhizome Iris as a group 
called wetland Iris from all the others which seem to be more closely 
related and termed Dryland Iris. This means that the rhizome group is split 
apart with the bearded being more closely related to the bulbous than 
previously thought. In the past there were two bulbous groups the 
Reticulatas and the Xiphiums(dutch Iris) which were thought to have evolved 
independently, there is some evidence that they may have shared a common 
ancestor. Three genera that were formerly separated from Iris are now 
included in the genus; Hermodactylus, Belamcanda, and Pardanthopsis. The 
crested Irises are a very artificial group which is still confused but each 
of these species should fall either in the bearded group or in the 
beardless group.

Since it is such a large topic I am attaching a handout that I use in my 
lectures that lists most of the species. I am still in the process of 
revising this piece so not everything in it is according to my gospel but 
it may be useful for our discussion. Please feel free to make a personal 
copy but don't distribute it as I want to use it in further lectures. I 
always have to redo some of the formatting on this file when I open it so I 
hope you will be able to get a reasonable copy, good luck.

Note from Mary Sue:
This came to me  instead of the list since it had an attachment. I have 
sent his attachment to the wiki. I am afraid it is a rather large file so 
it will take a little time to open depending on your connection. I couldn't 
change it to a html file for everyone to see without losing the formatting. 
But it looks like a treasure of information:…
  I have also turned Bob's message into text and am redirecting it to the list.

Mary Sue

More information about the pbs mailing list