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  • Thank you. I have two missions here today.

  • The first is to tell you something about pollen, I hope,

  • and to convince you that it's more than just something that gets up your nose.

  • And, secondly, to convince you

  • that every home really ought to have a scanning electron microscope.

  • (Laughter)

  • Pollen is a flower's way of making more flowers.

  • It carries male sex cells

  • from one flower to another.

  • This gives us genetic diversity,

  • or at least it gives the plants genetic diversity.

  • And it's really rather better not to mate with yourself.

  • That's probably true of humans as well, mostly.

  • Pollen is produced by the anthers of flowers.

  • Each anther can carry up to 100,000 grains of pollen,

  • so, it's quite prolific stuff.

  • And it isn't just bright flowers

  • that have pollen; it's also trees and grasses.

  • And remember that all our cereal crops are grasses as well.

  • Here is a scanning electron micrograph of a grain of pollen.

  • The little hole in the middle, we'll come to a bit later,

  • but that's for the pollen tube

  • to come out later on. A very tiny tube.

  • So, that's 20 micrometers across,

  • that pollen grain there.

  • That's about a 50th of a millimeter.

  • But not all pollen is quite so simple looking.

  • This is Morina. This is a plant --

  • which I've always thought to be rather tedious --

  • named after Morin,

  • who was an enterprising French gardener,

  • who issued the first seed catalog

  • in 1621.

  • But anyway, take a look at its pollen.

  • This is amazing, I think.

  • That little hole in the middle there is for the pollen tube,

  • and when the pollen finds its special female spot

  • in another Morina flower,

  • just on the right species, what happens?

  • Like I said, pollen carries the male sex cells.

  • If you actually didn't realize that plants have sex,

  • they have rampant, promiscuous

  • and really quite interesting and curious sex. Really.

  • (Laughter) A lot.

  • My story is actually not about plant propagation,

  • but about pollen itself.

  • "So, what are pollen's properties?" I hear you ask.

  • First of all, pollen is tiny. Yes we know that.

  • It's also very biologically active,

  • as anyone with hay fever will understand.

  • Now, pollen from plants, which are wind-dispersed --

  • like trees and grasses and so on --

  • tend to cause the most hay fever.

  • And the reason for that is they've got to chuck out

  • masses and masses of pollen to have any chance

  • of the pollen reaching another plant of the same species.

  • Here are some examples --

  • they're very smooth if you look at them --

  • of tree pollen that is meant to be carried by the wind.

  • Again -- this time, sycamore -- wind-dispersed.

  • So, trees: very boring flowers,

  • not really trying to attract insects.

  • Cool pollen, though.

  • This one I particularly like.

  • This is the Monterey Pine, which has little air sacks

  • to make the pollen carry even further.

  • Remember, that thing is just about 30 micrometers across.

  • Now, it's much more efficient if you can get insects to do your bidding.

  • This is a bee's leg

  • with the pollen glommed onto it from a mallow plant.

  • And this is the outrageous and beautiful

  • flower of the mangrove palm.

  • Very showy, to attract lots of insects to do its bidding.

  • The pollen has little barbs on it,

  • if we look.

  • Now, those little barbs

  • obviously stick to the insects well,

  • but there is something else that we can tell from this photograph,

  • and that is that you might be able to see a fracture line

  • across what would be the equator of this, if it was the Earth.

  • That tells me that it's actually been fossilized, this pollen.

  • And I'm rather proud to say

  • that this was found just near London, and that 55 million years ago

  • London was full of mangroves.

  • Isn't that cool?

  • (Laughter)

  • Okay, so this is another species evolved to be dispersed by insects.

  • You can tell that from the little barbs on there.

  • All these pictures were taken with a scanning electron microscope,

  • actually in the lab at Kew Laboratories.

  • No coincidence that these were taken

  • by Rob Kesseler, who is an artist,

  • and I think it's someone with a design and artistic eye

  • like him that has managed to bring out the best in pollen.

  • (Laughter)

  • Now, all this diversity

  • means that you can look at a pollen grain

  • and tell what species it came from,

  • and that's actually quite handy if you

  • maybe have a sample and you want to see where it came from.

  • So, different species of plants

  • grow in different places,

  • and some pollen carries further than others.

  • So, if you have a pollen sample,

  • then in principle, you should be able to tell

  • where that sample came from.

  • And this is where it gets interesting for forensics.

  • Pollen is tiny. It gets on to things, and it sticks to them.

  • So, not only does each type of pollen look different,

  • but each habitat has a different combination of plants.

  • A different pollen signature, if you like,

  • or a different pollen fingerprint.

  • By looking at the proportions and combinations

  • of different kinds of pollen in a sample,

  • you can tell very precisely where it came from.

  • This is some pollen embedded in a cotton shirt,

  • similar to the one that I'm wearing now.

  • Now, much of the pollen will still be there

  • after repeated washings.

  • Where has it been?

  • Four very different habitats might look similar,

  • but they've got very different pollen signatures.

  • Actually this one is particularly easy, these pictures were all taken

  • in different countries.

  • But pollen forensics can be very subtle.

  • It's being used now to track

  • where counterfeit drugs have been made,

  • where banknotes have come from,

  • to look at the provenance of antiques

  • and see that they really did come from the place

  • the seller said they did.

  • And murder suspects have been tracked

  • using their clothing,

  • certainly in the U.K., to within an area

  • that's small enough that you can send in tracker dogs

  • to find the murder victim.

  • So, you can tell from a piece of clothing

  • to within about a kilometer or so,

  • where that piece of clothing has been recently

  • and then send in dogs.

  • And finally, in a rather grizzly way,

  • the Bosnia war crimes;

  • some of the people brought to trial were brought to trial

  • because of the evidence from pollen,

  • which showed that bodies had been buried,

  • exhumed and then reburied somewhere else.

  • I hope I've opened your eyes,

  • if you'll excuse the visual pun, (Laughter)

  • to some of pollen's secrets.

  • This is a horse chestnut.

  • There is an invisible beauty all around us,

  • each grain with a story to tell ...

  • each of us, in fact, with a story to tell

  • from the pollen fingerprint that's upon us.

  • Thank you to the colleagues at Kew,

  • and thank you to palynologists everywhere.

  • (Applause)

Thank you. I have two missions here today.

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B2 US TED pollen grain flower electron sample

【TED】Jonathan Drori: Every pollen grain has a story (Jonathan Drori: Every pollen grain has a story)

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    Zenn posted on 2017/05/31
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