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It is well known that Ginkgo Biloba trees have sexual difference. There are male trees and female ones. I've seen female trees in Japan in the proper season, which is about now, there are lots and lots of fruit that fall under them. They vaguely look like plums, but when crushed they stink like dog's poop.

Now today, in France, I saw a huge Ginkgo Biloba, 150 years old, in a public botanical garden. Since it is a rather remarkable tree, they have put a panel telling its age, its size and specifying it is male. And indeed, if it were female there would be scores and scores of fruit below it.

But I saw one thing below it, looking vaguely like a plum, quite clean on one side, and a bit crushed on the other side. I picked it up, the skin was smooth to the touch, and smelled the crushed side, it stank like dog's poop. So it was quite obviously a Ginkgo Biloba fruit.

Is it possible that the male tree had, exceptionally, at least one female flower, was self-pollinated (or perhaps, was pollinated by another, younger and smaller Gingko Biloba tree in the same public garden but about 100 meters away, also male since there were no fruit below it either) and produced a fruit ?

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It is normally dioecious as the OP states, however there are occasional exceptions.

A male Ginkgo tree at Kami Yagisawa, Minobu-cho, Yamanashi Prefecture, Japan, is shown to possess a small, localized, branch that produces ovules that mature into viable seeds. This tree is recognized as an Ohatsuki Icho because of the occasional production of pollen sacs on otherwise normal vegetative leaves, but most of the abundant male cones that it produces are of normal morphology.

Full text to be found at Researchgate Sex Conversion in Ginkgo biloba (Ginkgoaceae)

Looking up Ohatsuki Icho, gives "Pollen sticks to leaves", so an indication of another rare condition in which some of the catkins/cones that are pollen producing parts are found emerging from some leaves. - Thanks to Andrew T..

It is speculated that they evolved from monoecious trees, and that at some point the old pattern reasserts itself in a small (unspecified) number of specimens.

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  • $\begingroup$ Thanks. So I was right, just as the tree you mentioned in Japan, the one here in Paris must have somewhere a small part that bore at least one ovule. The fruit was really impossible to confuse from anything else. $\endgroup$
    – Alfred
    Commented Oct 22 at 22:49
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    $\begingroup$ Absolutely. Sex-change in some fish was familiar to me, but trees, a whole new area I'd not been aware of. I notice that the linked paper is only about 8 years old - there may be more research into this in the future. @Alfred $\endgroup$
    – Jiminy Cricket.
    Commented Oct 22 at 22:57
  • $\begingroup$ If anyone has a better translation of Ohatsuki Icho, then please feel free to edit the answer. $\endgroup$
    – Jiminy Cricket.
    Commented Oct 23 at 5:48
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    $\begingroup$ Looks like Ohatsuki Icho (オハツキイチョウ) refers to the species variant of Ginkgo biloba var. epiphylla Makino and it's from お葉付き, which roughly means "(pollen) sticks to leaves" (the quotation already explains the meaning). $\endgroup$
    – Andrew T.
    Commented Oct 23 at 10:51
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    $\begingroup$ @Wastrel - A sport is new, something not before seen, caused by a genetic mutation and is often is able to be passed on to offspring or through grafting. What this part of the tree has experienced is sex conversion, which (as this answer points out) has been documented in gingkos. If it developed, say, yellow and green stripes on the same leaves at the same time which persisted with propagation, that would be a sport. (If it doesn't already exist; that I don't know.) $\endgroup$
    – anongoodnurse
    Commented Oct 23 at 15:47

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