TED2010
Jonathan Drori: Every pollen grain has a story
Filmed:
Readability: 4
473,125 views
Pollen goes unnoticed by most of us, except when hay fever strikes. But microscopes reveal it comes in stunning colors and shapes -- and travels remarkably well. Jonathan Drori gives an up-close glimpse of these fascinating flecks of plant courtship.
Jonathan Drori - Educator
Jonathan Drori commissioned the BBC's very first websites, one highlight in a long career devoted to online culture and educational media -- and understanding how we learn. Full bio
Jonathan Drori commissioned the BBC's very first websites, one highlight in a long career devoted to online culture and educational media -- and understanding how we learn. Full bio
Double-click the English transcript below to play the video.
00:15
Thank you. I have two missions here today.
0
0
3000
00:18
The first is to tell you something about pollen, I hope,
1
3000
4000
00:22
and to convince you that it's more than just something that gets up your nose.
2
7000
3000
00:25
And, secondly, to convince you
3
10000
2000
00:27
that every home really ought to have a scanning electron microscope.
4
12000
3000
00:30
(Laughter)
5
15000
2000
00:32
Pollen is a flower's way of making more flowers.
6
17000
4000
00:36
It carries male sex cells
7
21000
2000
00:38
from one flower to another.
8
23000
2000
00:40
This gives us genetic diversity,
9
25000
2000
00:42
or at least it gives the plants genetic diversity.
10
27000
2000
00:44
And it's really rather better not to mate with yourself.
11
29000
4000
00:48
That's probably true of humans as well, mostly.
12
33000
4000
00:52
Pollen is produced by the anthers of flowers.
13
37000
2000
00:54
Each anther can carry up to 100,000 grains of pollen,
14
39000
5000
00:59
so, it's quite prolific stuff.
15
44000
2000
01:01
And it isn't just bright flowers
16
46000
2000
01:03
that have pollen; it's also trees and grasses.
17
48000
4000
01:07
And remember that all our cereal crops are grasses as well.
18
52000
3000
01:12
Here is a scanning electron micrograph of a grain of pollen.
19
57000
4000
01:16
The little hole in the middle, we'll come to a bit later,
20
61000
3000
01:19
but that's for the pollen tube
21
64000
2000
01:21
to come out later on. A very tiny tube.
22
66000
2000
01:23
So, that's 20 micrometers across,
23
68000
2000
01:25
that pollen grain there.
24
70000
2000
01:27
That's about a 50th of a millimeter.
25
72000
2000
01:29
But not all pollen is quite so simple looking.
26
74000
3000
01:32
This is Morina. This is a plant --
27
77000
3000
01:35
which I've always thought to be rather tedious --
28
80000
2000
01:37
named after Morin,
29
82000
2000
01:39
who was an enterprising French gardener,
30
84000
2000
01:41
who issued the first seed catalog
31
86000
2000
01:43
in 1621.
32
88000
2000
01:45
But anyway, take a look at its pollen.
33
90000
3000
01:49
This is amazing, I think.
34
94000
2000
01:51
That little hole in the middle there is for the pollen tube,
35
96000
2000
01:53
and when the pollen finds its special female spot
36
98000
3000
01:56
in another Morina flower,
37
101000
2000
01:58
just on the right species, what happens?
38
103000
3000
02:01
Like I said, pollen carries the male sex cells.
39
106000
3000
02:04
If you actually didn't realize that plants have sex,
40
109000
3000
02:07
they have rampant, promiscuous
41
112000
2000
02:09
and really quite interesting and curious sex. Really.
42
114000
2000
02:11
(Laughter) A lot.
43
116000
4000
02:15
My story is actually not about plant propagation,
44
120000
3000
02:18
but about pollen itself.
45
123000
2000
02:20
"So, what are pollen's properties?" I hear you ask.
46
125000
3000
02:23
First of all, pollen is tiny. Yes we know that.
47
128000
2000
02:25
It's also very biologically active,
48
130000
2000
02:27
as anyone with hay fever will understand.
49
132000
2000
02:29
Now, pollen from plants, which are wind-dispersed --
50
134000
3000
02:32
like trees and grasses and so on --
51
137000
3000
02:35
tend to cause the most hay fever.
52
140000
2000
02:37
And the reason for that is they've got to chuck out
53
142000
2000
02:39
masses and masses of pollen to have any chance
54
144000
2000
02:41
of the pollen reaching another plant of the same species.
55
146000
4000
02:45
Here are some examples --
56
150000
2000
02:47
they're very smooth if you look at them --
57
152000
3000
02:50
of tree pollen that is meant to be carried by the wind.
58
155000
3000
02:53
Again -- this time, sycamore -- wind-dispersed.
59
158000
2000
02:55
So, trees: very boring flowers,
60
160000
3000
02:58
not really trying to attract insects.
61
163000
3000
03:01
Cool pollen, though.
62
166000
2000
03:03
This one I particularly like.
63
168000
2000
03:05
This is the Monterey Pine, which has little air sacks
64
170000
3000
03:08
to make the pollen carry even further.
65
173000
2000
03:10
Remember, that thing is just about 30 micrometers across.
66
175000
4000
03:14
Now, it's much more efficient if you can get insects to do your bidding.
67
179000
3000
03:17
This is a bee's leg
68
182000
3000
03:20
with the pollen glommed onto it from a mallow plant.
69
185000
4000
03:24
And this is the outrageous and beautiful
70
189000
2000
03:26
flower of the mangrove palm.
71
191000
2000
03:28
Very showy, to attract lots of insects to do its bidding.
72
193000
3000
03:31
The pollen has little barbs on it,
73
196000
2000
03:33
if we look.
74
198000
2000
03:35
Now, those little barbs
75
200000
2000
03:37
obviously stick to the insects well,
76
202000
3000
03:40
but there is something else that we can tell from this photograph,
77
205000
2000
03:42
and that is that you might be able to see a fracture line
78
207000
2000
03:44
across what would be the equator of this, if it was the Earth.
79
209000
3000
03:47
That tells me that it's actually been fossilized, this pollen.
80
212000
3000
03:50
And I'm rather proud to say
81
215000
2000
03:52
that this was found just near London, and that 55 million years ago
82
217000
3000
03:55
London was full of mangroves.
83
220000
3000
03:58
Isn't that cool?
84
223000
2000
04:00
(Laughter)
85
225000
3000
04:03
Okay, so this is another species evolved to be dispersed by insects.
86
228000
3000
04:06
You can tell that from the little barbs on there.
87
231000
3000
04:09
All these pictures were taken with a scanning electron microscope,
88
234000
3000
04:12
actually in the lab at Kew Laboratories.
89
237000
2000
04:14
No coincidence that these were taken
90
239000
2000
04:16
by Rob Kesseler, who is an artist,
91
241000
2000
04:18
and I think it's someone with a design and artistic eye
92
243000
3000
04:21
like him that has managed to bring out the best in pollen.
93
246000
4000
04:25
(Laughter)
94
250000
2000
04:27
Now, all this diversity
95
252000
2000
04:29
means that you can look at a pollen grain
96
254000
2000
04:31
and tell what species it came from,
97
256000
3000
04:34
and that's actually quite handy if you
98
259000
2000
04:36
maybe have a sample and you want to see where it came from.
99
261000
3000
04:39
So, different species of plants
100
264000
2000
04:41
grow in different places,
101
266000
2000
04:43
and some pollen carries further than others.
102
268000
4000
04:47
So, if you have a pollen sample,
103
272000
3000
04:50
then in principle, you should be able to tell
104
275000
2000
04:52
where that sample came from.
105
277000
2000
04:54
And this is where it gets interesting for forensics.
106
279000
3000
04:59
Pollen is tiny. It gets on to things, and it sticks to them.
107
284000
4000
05:03
So, not only does each type of pollen look different,
108
288000
2000
05:05
but each habitat has a different combination of plants.
109
290000
4000
05:09
A different pollen signature, if you like,
110
294000
2000
05:11
or a different pollen fingerprint.
111
296000
3000
05:16
By looking at the proportions and combinations
112
301000
2000
05:18
of different kinds of pollen in a sample,
113
303000
3000
05:21
you can tell very precisely where it came from.
114
306000
3000
05:24
This is some pollen embedded in a cotton shirt,
115
309000
3000
05:27
similar to the one that I'm wearing now.
116
312000
3000
05:30
Now, much of the pollen will still be there
117
315000
2000
05:32
after repeated washings.
118
317000
2000
05:34
Where has it been?
119
319000
3000
05:37
Four very different habitats might look similar,
120
322000
2000
05:39
but they've got very different pollen signatures.
121
324000
3000
05:42
Actually this one is particularly easy, these pictures were all taken
122
327000
2000
05:44
in different countries.
123
329000
2000
05:46
But pollen forensics can be very subtle.
124
331000
2000
05:48
It's being used now to track
125
333000
2000
05:50
where counterfeit drugs have been made,
126
335000
2000
05:52
where banknotes have come from,
127
337000
3000
05:55
to look at the provenance of antiques
128
340000
2000
05:57
and see that they really did come from the place
129
342000
2000
05:59
the seller said they did.
130
344000
3000
06:02
And murder suspects have been tracked
131
347000
2000
06:04
using their clothing,
132
349000
2000
06:06
certainly in the U.K., to within an area
133
351000
3000
06:09
that's small enough that you can send in tracker dogs
134
354000
2000
06:11
to find the murder victim.
135
356000
2000
06:13
So, you can tell from a piece of clothing
136
358000
2000
06:15
to within about a kilometer or so,
137
360000
4000
06:19
where that piece of clothing has been recently
138
364000
2000
06:21
and then send in dogs.
139
366000
3000
06:24
And finally, in a rather grizzly way,
140
369000
3000
06:27
the Bosnia war crimes;
141
372000
2000
06:29
some of the people brought to trial were brought to trial
142
374000
3000
06:32
because of the evidence from pollen,
143
377000
2000
06:34
which showed that bodies had been buried,
144
379000
2000
06:36
exhumed and then reburied somewhere else.
145
381000
5000
06:41
I hope I've opened your eyes,
146
386000
2000
06:43
if you'll excuse the visual pun, (Laughter)
147
388000
2000
06:45
to some of pollen's secrets.
148
390000
2000
06:47
This is a horse chestnut.
149
392000
2000
06:49
There is an invisible beauty all around us,
150
394000
2000
06:51
each grain with a story to tell ...
151
396000
2000
06:53
each of us, in fact, with a story to tell
152
398000
2000
06:55
from the pollen fingerprint that's upon us.
153
400000
3000
06:58
Thank you to the colleagues at Kew,
154
403000
2000
07:00
and thank you to palynologists everywhere.
155
405000
2000
07:02
(Applause)
156
407000
4000
ABOUT THE SPEAKER
Jonathan Drori - EducatorJonathan Drori commissioned the BBC's very first websites, one highlight in a long career devoted to online culture and educational media -- and understanding how we learn.
Why you should listen
Jonathan Drori has dedicated his career to media and learning. As the Head of Commissioning for BBC Online, he led the effort to create bbc.co.uk, the online face of the BBC (an effort he recalls fondly). He came to the web from the TV side of the BBC, where as an editor and producer he headed up dozens of television series on science, education and the arts.
After almost two decades at the BBC, he's now a director at Changing Media Ltd., a media and education consultancy, and is a visiting professor at University of Bristol, where he studies educational media and misperceptions in science. He continues to executive produce the occasional TV series, including 2004's award-winning "The DNA Story" and 2009's "Great Sperm Race." He is on the boards of the Royal Botanic Gardens and the Woodland Trust.
(Photo: Lloyd Davis/flickr)
Jonathan Drori | Speaker | TED.com