Did you know that there are two main groups of Siberian Irises? There are the beloved Siberians that most of us have in our gardens, which, in nature, have 28 chromosomes. These are the ones most people recognize as "Siberian irises". But there is second group that has 40 chromosomes that is less well known. These are sometimes called Sino-siberians since they come from the mountains of southwest China and adjacent areas over into the Himalayas.
Since the chromosome numbers don't match well, hybrids between the two groups (subseries) are uncommon, though a few are known. The most familiar is probably 'Foretell' (McGarvey 1970). I'm not aware of any other that has been registered since then, so this inter-subseries cross has not been a very fertile area for hybridizers (although speaking of fertility, surprisingly, 'Foretell' is modestly fertile with the 28 chromosome group).
|I. chrysographes (black form)|
|'Dotted Line' (Reid 1992)|
|'Bronzy Marvel' (Reid, 1998)|
|Spence seedling 0840-030A|
|Spence seedling 0640-011E|
|Spence seedling 0840-024A|
So, it is good to see the area coming back to life. In particular Patrick Spence is producing new 40 chromosome hybrids at Cascadia Gardens in Washington state. If interested, you might like to check out an article on the 40s by Patrick in the most recent (Fall 2012) The Siberian Iris. Some of his recent seedlings are shown here too.
|'Blue Meadow Fly' (Ahlburg, 1986)|
So, if you can provide the requisite conditions and want to try something different, maybe give the 40 chromosome Siberians a try. And, if you like to take the road less traveled as a hybridizer, this is an area of opportunity. My guess is that the genetic potential here has only just started to be tapped.
(Thanks to Margaret Spence for several of the photos used here.)