# "x" or "by"



## swamprad (Feb 17, 2008)

For many years I've read about and grown orchids with very little input from others. Living much of my life in a rural area, I just didn't know anybody else that cared about orchids! Moving to the city and joining my local orchid society, I heard some people pronounce that little "x" in a cross as "by". In other words, the label says "niveum x concolor", but I hear people say "niveum by concolor", which surprised me.

My question is, is this the standard usage everywhere? Or is it correct to say "x" or "by", whichever you like? I don't want to be uncool, lol...


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## Candace (Feb 17, 2008)

People say crossed with, crossed by, by, onto, but not the letter X. Don't worry, you're cool:>


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## Heather (Feb 17, 2008)

I think it is great to write something x something and people recognize it means crossed to or with or by, or you can just write _roth_ x _phil_ and say _roth_ by _phil_ and everyone will know what you are speaking about. Does that make sense?


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## SlipperFan (Feb 17, 2008)

x as in "times" -- roth times phil, as per Candace and Heather.


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## rdlsreno (Feb 18, 2008)

X to me is the short cut for "by" in a cross.

Ramon


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## NYEric (Feb 18, 2008)

Candace said:


> Don't worry, you're cool:>



She knows, ask her daughter! oke: Yeah "by" is the common term.


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## SlipperKing (Feb 18, 2008)

The reason crosses are written as; Paph #1 X Paph #2 is plant #1 is the "mother" or seed carrying plant and the "X" or "by" is the pollen donor (male counter part). Between two plants being mated, you can get different genetic influences depending on which one carries the seed. One example would be green flowers. If your goal is green flowers, you want the "mother" or the seed carrying plant to be green. Mitochondria a "body" inside of living cells carries the gene(s) for the color green. Pollen has no mitochondria, so by crossing a green flower's pollen onto an non-green flower you would not pass on the gene(s). I believe this info is correct. If not, someone in our forum will be able help both of us out


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## PaphMadMan (Feb 22, 2008)

SlipperKing said:


> The reason crosses are written as; Paph #1 X Paph #2 is plant #1 is the "mother" or seed carrying plant and the "X" or "by" is the pollen donor (male counter part). Between two plants being mated, you can get different genetic influences depending on which one carries the seed. One example would be green flowers. If your goal is green flowers, you want the "mother" or the seed carrying plant to be green. Mitochondria a "body" inside of living cells carries the gene(s) for the color green. Pollen has no mitochondria, so by crossing a green flower's pollen onto an non-green flower you would not pass on the gene(s). I believe this info is correct. If not, someone in our forum will be able help both of us out



Oops... We seem to have fallen into the deep end of cell biology without a flotation device. I'll see if I can tread cytoplasm long enough to get us back to a nice cell wall to hang on to.

Yes, you can get different genetic influences from mother and father lines in plant breeding, and mitichondria are part of the reason, but they have nothing to do with flower color.

Mitochondria are one type of subcellular 'organelle' that do contain a few genes worth of DNA, and are normally inherited only from the mother in orchids and many other organisms, including humans. Some other species, including pine trees, do it the other way around and only get mitichondria from the father. Most cells of every living thing bigger than bacteria contain mitichondria, which play a large role in energy processing within the cell but not in color expression. They might influence overall plant vigor or preferred temperature range though.

Plastids are another type of subcellular organelle found in plants but not animals. They also contain a few genes and are typically inherited from only one parent or the other, the mother in orchids, and do play a role in color in flowers. Plastids that develop green pigment (chlorophyll) are called chloroplasts and are responsible for photosynthesis, and bring green color to flowers. Other plastids may develop red or yellow pigments, or store starch or protein depending on where they are in a plant, but all plastids in a plant are genetically the same. How they develop depends on where they are in the plant and overall developmental processes.

However, whether green color is expressed in the flowers and in what pattern is probably largely under control of DNA on the chromosomes, inherited equally from mother and father, not the plastids themselves. But I doubt that anyone has really studied this and it may be different even in closely related species. And in orchid hybrids beyond 2-3 generations there may be no record of what the mother's mother's mother's species was. Still, if you have a presence and pattern of green color that you really want to maintain in breeding, it can't hurt to use that plant as the mother in a cross.

PaphMadMan (Kirk)


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