ginkgo biloba

[Nick Longrich <nrlongri@midway.uchicago.edu>]

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

"The seedcoat delays germination and attracts animal dispersers once the seeds
fall off the tree. In the digestive system of the disperser the seedcoat is
removed
 and the seeds are taken away from the parent tree. The scarified seeds are
then
deposited in droppings, ready for immediate germination (if the new theory is
 correct that the embryo is well developed in seeds still attached to the
parent
tree).

  Dispersers in the times of the dinosaurs were the dinos and other herbivorous
reptiles which were attracted by the smell of the seedcoat. Nowadays dispersers
are the gray squirrel, birds, possibly crows, mice and in Japan a badger
 ("hondo-tanuki" = Nyctereutes procyonoides) and the Paguma larvata, a
cat-like animal eat the seeds for their seedcoats. This dispersal allows the
distribution of the species and transport to some place where there may be less
competition for light or other resources. "

        This is just a random page by a ginkgo enthusiast and of course the
dinosaur stuff is speculative, none the less it seems plausible to me that
the seedcoat is helping to disperse the fruit. It looks like a fruit, it
doesn't seem like we need to come up with elaborate explanations for that
if we can just say it's convergent on a fruit.
        Nor is there anything particularly unusual about smelly fruit, a
number of fruit smell, apparently to attract animal(particularly mammal)
dispersers. I doubt that even the rancidness of ginkgos would turn off
mammals- I once read about someone trying to clean a turkey skeleton by
macerating it (put the bones in a bucket for a month, and leave them there.
It smells about like you'd imagine, only ten times worse), and anyway,
their dog got into the bucket and drank a whole bunch of the water. Point
being, mammals are not necessarily known for what we would call
discriminating taste...  Nor do we necessarily have to come up with
elaborate theories for extinction- extinction happens. Dawn redwoods are an
ancient genus, but in recent times have been reduced down until not that
many remain in the wild, a situation analogous to the ginkgo, but the dawn
redwood doesn't have any unusual reproductive mechanisms that could explain
this.
        So I'm not saying that the ginkgo berry couldn't be more than just
your average fleshy seedcoat that attracts dispersers, and I'm not saying
that there couldn't be something weird about ginkgos that has caused them
to do poorly in recent millennia, but in the absence of any compelling
arguments and evidence otherwise, it seems simply more parsimonious (in the
broad sense and not the narrow cladistic sense) that it isn't doing
anything all that weird.