Re: Physical effects versus Gene expression

On non-SA's the flowers with missing parts or arranged in sets of two of everything instead of three more often were the last ones on bloomstalks with lots of buds--in Idaho.  It was as if the plant was tired and just couldn't quite put out any more.  I don't recall seeing any odd ones as firsts.
 
Sometimes a flower would have a standard that was a fall instead, so it had two standards, four falls, three or four style arms.  These happened now and again, and were usually at one end or the other of the bloom season--first or last, or nearly so.
 
I haven't noticed much if any such abnormalities here in NC, yet--but probably will as the soil matures and growth of the iris normalizes.
 
Mary Tharp, my first mentor, would never use pollen or pod from abnormal flowers.  I never hesitated to use
 them--the condition was not a genetic mutation, it had to do with development, which now I would describe as a matter of growth hormones being out of control.
 
I'd like to add a little bit about hormones.  Most of us have used Rootone.  Or perhaps have used the same thing with another brand name.  This is a dilute formulation of a plant hormone called by the acronym "NAA,"  NAA stands for "naphthalene acetic acid" and has a number of effects on plant growth.  One of them has to do with cell extension and also has an influence on the determination of what kind of cell an embryonic cell becomes as it matures.  The "cell extension" effect is the primary one when used as a rooting hormone. 
 
One of the ways to get a young apple tree to start forming fruit instead of stem buds is a Japanese-developed trick we called "bending and twisting."  This works with a lot of other ornamental and fruit plants too. 
 
An upright shoot keeps on growing upright as a juvenile, non-fruiting or flowering stem.  To get it to change and start maturing and blooming or bloom and set fruit, one can take the stem while it is soft and in rapid growth form--this would be early June in SW Idaho, probably a month or so earlier here in NC--and carfully, slowly bend the branchlet around or even form a loop with it, bending it back and forth sideways and up and down, being careful not to break off the branch near the base. 
 
What one is doing is weakening the woody inner "xylem" cells, cracking them so that the branch is no longer upright, but sags over at an angle, at least 45 degrees from the horizontal.
 
Then what happens is that NAA, as it is formed in growing tips, tends to be pulled down by gravity so that the underside of the branch has more, the upper side less of the hormone.  After a year, the stem has started forming fruiting buds because of the gradient of the hormone. It is no longer uniform in the stem.
 
There are several other hormones, such as IAA (same as NAA, but is indole- instead of naphthalene-), gibberellins (I am unsure of my spelling on that one) --used on grapes as fruit set begins, for example, so that the clusters are larger and fuller.  
 
Another we make use of all the time and don't even realize what we are doing.  If one puts bananas, apples and pears together in a bowl of fruit, or better yet, in a paper sack, the ones that are more ripe put out a gas named ethylene.  Ethylene is a ripening hormone.  All the fruit in the sack (or bowl) is affected, and tend to ripen together. 
 
This works better at room temperature than in the refrigerator.  If you have bananas or pears that need to ripen, put them together in a space that limits air movement--such as the bowl or sack (sack is better) so that the fruit still gets oxygen, but the ethylene is not lost.  Ripening fruit helps other green fruit to ripen also.  One can slow down the rate of ripening by chilling in the refrigerator, and keeping green fruit away from those ripening, and also making sure there is some air movement now and then (by getting into the refrigerator to get something).  This drains away the ethylene.  The drawers in the bottom of the refrigerator promote ripening more than the open shelves, by the way.
 
There are a host of other hormones.  Plant activities in general are mediated or moderated by hormones.  Iris are included in this.
 
We talk about planting spent (old mother) rhizomes.  Tilting them--so that the old toe is lower than the younger end, or cutting them up like potatoes for "seed" disturbs the hormone distribution so that those that are heavier than water tend to drift downward, those lighter drift upward in the rhizome.  This process tends to trigger growth bud development, so that new fans are formed.
 
Hormones also determine how and when the growing tip down inside the fan begins to change and makes stem and flowers instead of rhizome and leaves.
 
We also use false hormones--ones that are similar to natural ones, but have some chlorine involed.  Plant growth is disturbed and the plants die or are controlled somehow in an abnormal fashion--these include 2, 4 D and Agent Orange.  I suspect all herbicides do what they do because of a disturbance of the hormone activity in plants.
 
Abnormal iris flowers are the result of an excess or a depletion of growth and blossom regulating hormones.  That's why we see them first or last in the growth of the stalk.
 
Neil Mogensen   z 7  western NC
 
 

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