Irises forum→Why are variegated bearded iris blooms purple? Are they any other colors?

KentPfeiffer said:Your irises are probably a variety of Iris pallida. It's possible to cross them with modern tall bearded irises. However, Iris pallida is diploid with 24 chromosomes while nearly all modern TBs are 48 chromosome tetraploids.

There are a few tetraploid TBs with variegated leaves that could be used to produce new varieties.

First, variegation in irises is a recessive trait so, in TBs, all four copies of the allele for variegation would have to present in order for it to be expressed. If, for example, you cross a TB with variegated leaves to a TB with normal leaves, you'll likely get zero seedlings with variegated leaves. If you backcross those seedlings to the variegated parent or another variegated TB, you'll get a few variegated seedlings, but still most won't be. In other words, you'll have to do a lot of crosses to get a relatively small number of seedlings that show variegation.

The second challenge is that variegated seedlings often don't grow very well, so a good chunk of the seedlings you do get that have the trait you want, don't survive long enough to bloom.

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lauriemorningglory said:Very interesting info, Kent. Thank you.

I've wondered if the white portions "burn" more easily in the sun.

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KentPfeiffer said:
3. No. Ploidy in bearded iris is generally assumed rather than known. You can safely assume almost every TB introduced after 1950 is tetraploid. It's also a good bet that most TBs that existed prior to 1900 are diploid.

The transition from mostly diploid TBs to mostly tetraploid TBs happened some time in the early 20th century, almost certainly by accident and without the breeders being aware of what had happened. Tetraploid irises have flowers that are generally bigger, more ruffled, and come in a VASTLY wider array of colors and patterns than diploids. When tetraploid irises started showing up in seedling beds, breeders naturally chose them over diploid seedlings, simply because they were bigger and prettier. Keep in mind, we didn't even know how many chromosomes a human being has until the 1950's, let alone the chromosome count of an iris.

If you are determined to use Iris pallida, you might be better off crossing it with Miniature Tall Bearded irises, rather than trying to find diploid TBs. Most MTBs are diploids, although not all. Ben Hager and Kenneth Fisher introduced a number of tetraploid MTBs, starting back in the 80's or so. Paul Black, Thomas Johnson, and a few others are currently producing tetraploid MTBs. Nonetheless, diploid MTBs are still predominant because MTBs are supposed to have small and delicate flowers. Producing small flowers in tetraploids is a bit of a challenge.

MTBs also tend to be vigorous, a trait you are going to need if breeding for variegated leaves.

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Henhouse said:There are quite a few out there. As Kent said, many are not strong growers. I find I. pallida 'Aurea' to be pretty easy, with I. pallida 'Argentea' less so. Brad Kasperek worked on them quite a bit, and I think Mid-America was working on some.

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irisarian said:IBs were often sterile because of being mixed chromosome. Newer ones are fertile. Why would they be classified as TBs? They were originally missed than became TB X SDB & now can be just mixed and a certain size.

Australis said:Crimson King (or whatever it is) grows well for me. It doesn't have great form, but is hardy and vigorous. Biggest downside for me is that the blooms tend to get wrecked easily by the wild winter and early spring weather.

Ian, it's also worth noting that Crimson King isn't as big as today's TBs. It's the size of an IB.

'Saffron Drift' is another that multiplies well for me and has good branching.

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