Glass gem corn

Speaking of hybridization, my friend Nicole L’Or Reggia sent me some ears she grew of what’s called “glass gem corn,” which are gorgeous. I had no idea this stuff existed, though of course I’d seen less variegated “Indian corn” that appears around Halloween. Here are 12 ears: all of them are small: up to about six inches long. Some are highly variegated like a pack of Jelly Belly jelly beans, while others have a dominant color scheme (bottom of the second picture and the third picture).

Nicole gem corn



As the corn dries out, it becomes translucent, making it even more gemlike. The photos below show what my ears will eventually look like (photos are taken from various places, including the Glass Gem Corn Facebook page):





Go here for a gazillion more photos.

Now how are these produced? It’s hard to find much information about Glass Gem corn. It was clearly developed by breeding varieties of corn having different-colored kernels, but beyond that there’s little information about the breeding scheme. There’s a piece at Business Insiderand this from My Modern Met:

Nature often surprises us with the amazing things it produces, and Glass Gem corn is a fantastic instance of when the line between what’s real and fake is blurred. The rainbow-colored kernels resemble brilliantly-hued strands of jewels rather than something you’d find on your plate. They’re all natural, however, and are the result of heirloom-style farming as well as selective planting.

The story behind these special corn cobs started with an Oklahoma-based farmer named Carl Barnes. As an adult, the half-Cherokee Native American began growing older varieties of the crop as a way to reconnect to his roots. In doing this, he isolated heirloom corn seeds that were lost to Native American tribes when, in the 1800s, they were relocated to present-day Oklahoma.

Barnes shared and exchanged the ancient corn seeds with people he had met around the country, while he also selected and planted grains from the more colorful varieties. This is how the dazzling rainbow corn was born, but these weren’t crops that he kept to himself. Thanks to Barnes, fellow farmer Greg Schoen became acquainted with the vegetable in 1994 at a native-plant gathering in Oklahoma. Mesmerized by the colors, Barnes gave Schoen some of the seeds, who then planted the rainbow corn next to traditional yellow varieties. This mixture led to new and exciting hybrids.

Like Barnes, Schoen passed the seeds along to others, one being Bill McDorman. He owned an Arizona company called Seed Trust, and he’s now the Executive Director of Native Seeds/SEARCH. The non-profit conservation organization now sells the seeds online. [JAC: you can buy the seeds online for only $4.95 a packet.]

But beyond that, I see little information, though I’ve done only a cursory survey.  I’m hoping a reader with botanical expertise can explain these, but here’s what I know about corn (I hope this is right!):

  • Each “kernel” is the result of a separate pollination event, which clearly accounts for the different colors (they come from genetically different pollen and ovules). Corn is wind-pollinated, but is effectively self-incompatible as the tassels (male parts) are physically separated from the ears (female parts). The many different colors surely reflect many different kinds of pollen impinging on each ear. Each “silk” on an ear is a style: the tube through which the pollen will grow to produce a single kernel. Each “cob” involves several hundred fertilization events. I could plant each kernel and, if I plant more than one together, get more ears like these.
  • I have no information about the color diversity among ears from the same plant. By all rules of genetics, they should resemble each other more than ears from different plants, since ears of a single plant have a single female genotype.
  • Many ears have a dominant “theme” color, like the purple and reddish ears depicted above. That may reflect a female genotype carrying “red” or “purple” genes, or perhaps limited pollination (Nicole grew about a dozen plants), the dominance relationships of some color alleles, or all of the above.
  • I know squat about corn genetics, and even less about corn color genetics. To work out how ears like the above are possible, one needs to be able to show that each of the kernels on a given ear reflects the female’s genotype in the ovule (limited to two alleles at each color locus) combined with a substantially larger variety of alleles in the pollen that fertilizes the female. And you’d have to know the dominance relationships as well as the number of genes producing each color.

And that’s where my knowledge stops. Readers who know about corn varieties or corn genetics are invited to weigh in.

Oh, and about its edibility. Apparently it’s not edible like regular corn on the cob, but you can cut the dried kernels off the cob to make popcorn. Then, however, the color disappears. Or I could plant the kernels, though growing space is sparse in my neck of the woods.  I’d prefer to let my ears dry out, become gemlike, and then show off the ears as a lovely novelty.



  1. Gregory Kusnick
    Posted October 23, 2016 at 1:13 pm | Permalink

    I know even less about this than you do, but it seems at least conceivable that the different colors could be due in part to different patterns of gene activation during the development of each kernel. So the kernels might be more genetically homogeneous than the colors would suggest.

    But I’m just guessing.

    • Posted October 23, 2016 at 1:24 pm | Permalink

      I doubt it, because that just pushes the problem back one level: there would have to be heterogeneous genetic patterns of gene activation (and, indeed, that could EXPLAIN the color differences unless you think that local environmental differences change the color, and I doubt that because domestic corn doesn’t show that kind of variation.

  2. harrync
    Posted October 23, 2016 at 1:14 pm | Permalink

    Are you sure those aren’t art works made with cabochon semi-precious gems?

  3. Monika
    Posted October 23, 2016 at 1:15 pm | Permalink

    Ooooh pretty! If only I had a garden…

  4. Randall Schenck
    Posted October 23, 2016 at 1:24 pm | Permalink

    I was going to ask, is it popcorn or just field corn? Pretty sure not “sweet” corn. We still have a popcorn sheller that does a great job of shelling the corn from the cob. If it were sweet corn it can be dried and then cooked – referred to as parched corn. Just put in a pan and add oil. It goes off like popped corn but it is just parched (swells up) if that makes sense to you.

    I think this gets vary popular around Halloween.

  5. Posted October 23, 2016 at 1:29 pm | Permalink


  6. Darren Garrison
    Posted October 23, 2016 at 1:36 pm | Permalink

    I discovered the existence of glass gem corn a few months back and was also amazed by it.

    PCC Said:
    “Apparently it’s not edible like regular corn on the cob, but you can cut the dried kernels off the cob to make popcorn.”

    Also a few months back I was reading the wiki on maize, and learned that it (like most things) is more complicated when you look at it closer. When I (and probably others) think of “corn”, I almost always thing of the cob-edible variety, but it actually has several broad sub-types:

    Glass gem corn, I believe, fits in the “flint corn” variety.

  7. Posted October 23, 2016 at 1:54 pm | Permalink

    Here’s one reference on corn kernal colors that has a nice explanation on the first page (4 genes involved). Aimed at science teachers. I can’t read the whole article; maybe you can.

    • Mark Sturtevant
      Posted October 23, 2016 at 2:55 pm | Permalink

      This is interesting. I suspect some of this has to do with various relationships between alleles of genes, like dominant, recessive, and for some maybe incomplete dominance. That, along with a few different pigments like carotenoids for yellow and anthocyanins for red and blue. So when pigments are combined you would get new colors.
      For example, kernels that produce both blue and yellow pigment would come out looking green. One can also predict other colors made by other combinations. Throw in some incomplete dominance where there are different shades of yellow, red, or blue, then the combinations come out with yet more color effects.
      Here we are unweaving the rainbow, maybe, but they are still just as lovely.

  8. Posted October 23, 2016 at 1:55 pm | Permalink

    A Nature Review Genetics article that probably has more than we’d want to know about the subject. Again, I can’t see it.

  9. busterggi
    Posted October 23, 2016 at 2:16 pm | Permalink

    I already do plenty of leaf-peeping by default of driving to work and back. I look forward to corn-peeping.

  10. Woof
    Posted October 23, 2016 at 2:27 pm | Permalink


    Just don’t let your squirrel buddies get into them.

  11. GBJames
    Posted October 23, 2016 at 2:52 pm | Permalink


  12. GBJames
    Posted October 23, 2016 at 2:54 pm | Permalink

    Does the color disappear when the kernel is removed from the cob or when the kernel is popped. (The last paragraph is ambiguous on this. I would expect it to not happen until it was popped.)

    • Mark Sturtevant
      Posted October 23, 2016 at 2:58 pm | Permalink

      Kernel color is from a thin pigment layer in the seed coat. Much of the insides of a kernel are nutrient endosperm, and that will be white. When a kernel pops it sort of turns itself inside out, bubbling out the endosperm.

    • Gregory Kusnick
      Posted October 23, 2016 at 3:03 pm | Permalink

      Mark typed faster than I did.

      Bottom line is that the color doesn’t really disappear; it was never in the poppable part in the first place.

      • GBJames
        Posted October 23, 2016 at 3:39 pm | Permalink

        That is what I would expect. But the wording left (in my mind) the possibility that removing the kernels would somehow alter the way light interacted with them. Or something.

  13. Posted October 23, 2016 at 2:59 pm | Permalink

    I suppose that transposable elements may have something to do with the observed diversity of color.

  14. Kevin
    Posted October 23, 2016 at 6:14 pm | Permalink

    Holy Corn Batman!

  15. Michael Scullin
    Posted October 23, 2016 at 7:01 pm | Permalink

    The Corn “is effectively self-incompatible as the tassels (male parts) are physically separated from the ears (female parts).”

    As Donald Trump would say: “Wrong. Wrong. Wrong.” I’ve been working with corn (maize) for forty years now. And I have worked on it as well on archaeological sites in corn fields. Corn pollen is big (about 100 microns) and heavy, distinctively round (spherical), and itchy. For the most part it falls pretty much straight down except when the wind is blowing.

    Because of space limitations our test plots are close (5×4 hills with 4 feet between hills each with with 5 or 6 kernels). We have about 8 feet between plots and relatively little crossing. When crossing occurs the cross pollinated (between plots) kernels are just not planted. Works very well and was probably done the same way for about the past 1000 years north of Mexico when’re the first maize dates to about a 9000 years ago.

    The corn shown is a flint (very hard starch in the kernels) which has a pearly seed coat. Native American maize from Illinois probably was about this size (my wife is studying the phytoliths from a variety grown about 1000 years ago from a site just east of Cahokia which is just across the Mississippi River from St. Louis). The colors shown are the sort of sports which just show up and can very easily be selected for but not so easily in the rainbow spectrum seen here.

    It was the variable patterns and colors of corn that Barbara McClintock studied and figured out “jumping genes,” which no one seemed interested in, but which ultimately got her the Nobel Prize. Years ago I took some “Indian corn” as sold in grocery stores at this time of year and starting with some red kernels got a corn plant with red leaves, tassels, cobs and kernels in 8 generations.

    We watch a lot of BBC productions and se maize grown in England which is all above the 49th parallel. Not bad for a plant domesticated on the Tropic of Cancer.

    The jewel corn would be as edible as any corn were it picked in the milk stage. Northern Flint was sold as “sweet corn” into the 1950s or so when hybrids were developed. Native Americans might eat as much as a third of their crop as sweet corn and as an important component of a very widespread ceremony known as “The Green Corn Ceremony.”

    • Diane G.
      Posted October 24, 2016 at 2:24 am | Permalink

      “Years ago I took some “Indian corn” as sold in grocery stores at this time of year and starting with some red kernels got a corn plant with red leaves, tassels, cobs and kernels in 8 generations.”

      Wow, very cool!! Along with all of the other fascinating info in your post–thanks!

  16. Diane G.
    Posted October 24, 2016 at 2:26 am | Permalink

    “Each “silk” on an ear is a style.”

    I did not know that–neat!

    Beautiful corn, great read!

  17. Hempenstein
    Posted October 24, 2016 at 10:38 am | Permalink

    Too bad you can’t just pop over to George Beadle’s office and ask him. I recall he kept a corn patch even while president of UC. (Are there any memorials to him there?)

  18. Posted October 24, 2016 at 11:55 am | Permalink

    Wow. I had no idea such a thing was possible. And even more astonishing when one looks at the reconstructions of what teosinte would have looked like.

    Also, go “genetic craft!”

  19. Saul Sorrell-Till
    Posted October 24, 2016 at 12:45 pm | Permalink

    “all of them are small: up to about six inches”.

    I found this very insulting frankly. Six inches is not ‘small’, it’s perfectly sufficient, unless the person is unreasonably demanding, and most people would be very happy with a cob that size, or even smaller.
    I would imagine anyway, as I don’t have any personal experience of ‘small’ cobs. And, again, six inches is not small. Not that I’d know, as I just said.

    Apart from this one issue, lovely post.

    • Diane G.
      Posted October 24, 2016 at 2:54 pm | Permalink


  20. Redlivingblue
    Posted October 26, 2016 at 7:30 am | Permalink

    I never would have guessed that I would have enjoyed reading about corn… Thanks for the post and pics!

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