Thread: can ginkgo seeds be sterile?

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  1. #1

    Join Date
    Oct 2006
    Location
    Rochester, MN, USA (zone 4)
    Posts
    1

    can ginkgo seeds be sterile?

    This is the time of year (in Minnesota, at least) when female ginkgo trees drop their seeds. Since ginkgo trees have both male & female genders (dioecious), and both genders are required to produce fertile seed, my question is: if a female ginkgo tree drops an apparently developed seed, does that mean that the seed was fertilized by a nearby male tree? Or can the seeds appear to develop normally even without fertilization (in which case they'd be sterile, of course).

    Normally, I would assume that a developed seed would indicate that it had been fertilized, but ginkgo trees are so unusual that I'm not sure.

    Thanks,
    Jon

  2. #2
    Oak
    Join Date
    Jun 2004
    Location
    Lincoln, Nebraska - Lancaster County (Zone 5)
    Posts
    256

    RE: can ginkgo seeds be sterile?

    Hello Jon,

    As I understand the process most ginkgo fruit is fertilized while the seed is still on the tree. This normally takes place over a period of about 10 to 14 days. However, it is possible that some of the fruit can still be fertilized after it has dropped to the ground. Of course weather and local factors can influence this process from year to year.

    While the ginkgo is usually dioecious, occasionally both genders can be found on the same tree. Most gingko trees offered by nurseries here in the United States are grafted male trees.

    The fertilization of gingko was a mystery until a Japanese scientist named, Sakugoro Hirase observed swimming sperm for the first time in the seeds of a female ginkgo tree growing in the Botanical Garden of the University of Tokyo in Japan in 1896.

    To learn more about the fertilization of ginkgo, please visit these websites:

    1. The Gingko Pages: Propagation

    http://www.xs4all.nl/~kwanten/propagation.htm

    2. Dr. Robert W. Ridge: Brief Notes on Ginkgo biloba

    Dr. Ridge teaches cell biology, molecular plant development, plant morphology and structure laboratory classes at the International Christian University in Tokyo.

    http://mac122.icu.ac.jp/ginkgo/icho.html

    "Authors disagree as to whether the whole spermatid enters the archegonium, or whether the flagella apparatus is left behind. The nucleus of the spermatozoid separates and contacts the egg nucleus, forming a diploid zygote. It has been suggested that fertilization and embryogenesis may occur either on the tree or on the ground. In our experience at Tsukuba, fertilization occurs on the tree, but as the fruit falls soon after this period, embryogenesis probably occurs on the ground. I'm sure this may differ from region to region and according to the weather. Of course, removing the fruits from the tree doesn't affect fertilization, so it is quite feasible that fertilization could occur on the ground."

    This is an interesting - but tough question Jon. I've tried to address it as best that I can. Do we have a botanist in the Forum that is willing to lend their perspective on this subject?
    Sincerely, Robert
    Lincoln, NE (Zone 5)

    Even if I knew that tomorrow the world would go to pieces, I would still plant my apple tree.
    - Martin Luther (1483-1546)

  3. #3

    RE: can ginkgo seeds be sterile?

    Those Ginkos sure have a nice form.

    I just located an older one in Medford, Oregon, prior to teaching a tree care class.

    It will make a good example to study in the next few years.

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