1 00:00:00,330 --> 00:00:05,640 Hello, my name's Lindsay Turnbull and I'm an associate professor in the Department of Plant Sciences 2 00:00:05,640 --> 00:00:10,740 at the University of Oxford, and we're right in the middle of this very serious corona virus crisis right 3 00:00:10,740 --> 00:00:15,810 now. And my students are all stuck at home and we want to keep them in touch with biology 4 00:00:15,810 --> 00:00:21,240 and keep in touch with us. And so we're going to make a new series of videos and they're going to be called back garden 5 00:00:21,240 --> 00:00:46,750 biology. 6 00:00:46,750 --> 00:00:51,820 Hello, welcome to this episode of Back Garden Biology, I I'm sitting in 7 00:00:51,820 --> 00:00:56,860 my lawn and there are quite a lot of bits of my lawn that I let grow 8 00:00:56,860 --> 00:01:01,900 quite wild and we only mow them at the end of the summer and that allows all kinds 9 00:01:01,900 --> 00:01:07,120 of plants to establish in the lawns. Of course, we think of lawns as being just consisting of grass 10 00:01:07,120 --> 00:01:12,430 and that's mostly what people want to lawn to consist of. And some people, of course, spend a lot 11 00:01:12,430 --> 00:01:17,500 of time trying to remove any other plants from their lawn mowers. Wage war 12 00:01:17,500 --> 00:01:24,100 against moth. They wage war against daisies and dandelions and they only want to have grass in their lawn. 13 00:01:24,100 --> 00:01:29,320 So in a conservation lawn rather than grass, you want to have lots of other things, 14 00:01:29,320 --> 00:01:34,480 growing wildflowers, etc. But actually what people often find is that it's really 15 00:01:34,480 --> 00:01:39,520 difficult to get them to establish so you can throw in tons of seed of all kinds 16 00:01:39,520 --> 00:01:44,530 of different species that you'd like to have and find that nothing ever establishes. And that's 17 00:01:44,530 --> 00:01:49,750 because grass is actually a really good competitor. And once you've got a good sward of grass established 18 00:01:49,750 --> 00:01:54,850 over things can find it quite difficult to invade. But there is a plant 19 00:01:54,850 --> 00:02:00,160 that if you sow it seeds into your lawn and your lawn isn't too dense and thick, 20 00:02:00,160 --> 00:02:05,350 has a pretty good chance of establishing. And it's called hay rattle or yellow 21 00:02:05,350 --> 00:02:10,570 rattle. Now, the reason that the hay rattle is able to establish 22 00:02:10,570 --> 00:02:15,760 in your lawn when lots of other wildflowers might find it difficult is because hay rattle is not 23 00:02:15,760 --> 00:02:21,910 an ordinary plant. It's got a special trick up its sleeve and it's what we call a Hemi parasite. 24 00:02:21,910 --> 00:02:27,010 Now, about half the species on this planet, amazingly, are parasites of one sort or another, 25 00:02:27,010 --> 00:02:32,410 and they are freeloading on the other half. Now, hey, Rattle is a hemi parasite. 26 00:02:32,410 --> 00:02:37,480 That means it doesn't rely entirely on parasitism. And we can see that it has nice green 27 00:02:37,480 --> 00:02:42,870 leaves which do conduct photosynthesis, but it doesn't have very many leaves and they're quite small. 28 00:02:42,870 --> 00:02:48,370 So it's surprising that it's so successful. But below ground, the hay rattled doesn't produce 29 00:02:48,370 --> 00:02:53,500 any proper rates. Instead, what it does is it plugs into 30 00:02:53,500 --> 00:02:58,900 the roots of grasses and it plugs into their xylem vessels, which are conducting 31 00:02:58,900 --> 00:03:05,410 water, mineral nutrients, and it taps off their water and then mineral nutrients. 32 00:03:05,410 --> 00:03:10,570 The effect of adding hay rattle into a piece of grass is that it starts 33 00:03:10,570 --> 00:03:15,700 to weaken the grasses. And that means that it's easier to get some of the wildflowers 34 00:03:15,700 --> 00:03:21,100 that you want to grow in your lawn to actually establish because they struggle to compete against 35 00:03:21,100 --> 00:03:26,200 the grasses, especially if you've been fertilising your lawn until fairly recently. 36 00:03:26,200 --> 00:03:31,240 Now, there are lots of schemes up and down the country where people are trying to restore wildflower meadows. They're trying 37 00:03:31,240 --> 00:03:36,910 to turn that area of just grass into a meadow which is filled with lots of different species. 38 00:03:36,910 --> 00:03:42,040 And this hay rattle is one way that they can help. That can really help them to do that. 39 00:03:42,040 --> 00:03:47,530 So they so back in with the wildflowers in the hope that it will emerge and start Parisot 40 00:03:47,530 --> 00:03:52,890 ising the grasses are make it easier for other wildflowers to establish. 41 00:03:52,890 --> 00:03:58,150 So in this episode we're going to go out to my local park where there are some areas where they're trying to restore 42 00:03:58,150 --> 00:04:03,190 meadows. I mean we can see lots of rain up this growing. And later in the programme we're going to hear 43 00:04:03,190 --> 00:04:08,200 about some other parasitic plants, including mistletoe, which is probably a familiar thing at 44 00:04:08,200 --> 00:04:13,570 Christmas at least. And Rob Salguero Gomez, he works in the Department of Zoology, 45 00:04:13,570 --> 00:04:23,310 has a study going on that plants we're going to find out a little bit about what he's doing. 46 00:04:23,310 --> 00:04:29,160 Hello, my name is Chris Thoroughgood, and I'm going to be talking about this seemingly 47 00:04:29,160 --> 00:04:34,220 unattractive plant, but it's very, very interesting. This is a broom rape. 48 00:04:34,220 --> 00:04:39,690 Its scientific name is are a banki. And why is it interesting? It's parasitic. 49 00:04:39,690 --> 00:04:44,880 So it steals all of its food. It robs its existence from the roots 50 00:04:44,880 --> 00:04:49,950 of green plants. And you'll notice that this plant has no green leaves or chlorophyll 51 00:04:49,950 --> 00:04:55,020 of its own. It also produces no functional roots either. And 52 00:04:55,020 --> 00:05:00,270 as a seedling, it attaches to the roots of other plants, in this case to the roots of an I.V. 53 00:05:00,270 --> 00:05:05,670 And then it siphons off its food. Now, broadly speaking, we can divide parasitic 54 00:05:05,670 --> 00:05:10,920 plants into those that are photosynthetic. Still, the hammie parasites, they have their own leaves 55 00:05:10,920 --> 00:05:16,080 and chlorophyll and those that are not and are completely dependent upon their hosts for 56 00:05:16,080 --> 00:05:21,600 their survival, such as this bring right now parasitic plants can have 57 00:05:21,600 --> 00:05:26,820 what's being terms the Dracula effect. So they suck the life for the sap out of their host plant 58 00:05:26,820 --> 00:05:31,860 like this. What some of these parasitic plants have shifted from the wild 59 00:05:31,860 --> 00:05:37,380 vegetation to cultivated crops. So which weed is one particularly 60 00:05:37,380 --> 00:05:42,510 pernicious weed that across Africa and Asia can have devastating effects on crops? 61 00:05:42,510 --> 00:05:47,520 It costs about devastates about ten billion dollars worth of crops every year. So 62 00:05:47,520 --> 00:05:52,530 it's a real problem for farmers. So it's it's worth studying and understanding these 63 00:05:52,530 --> 00:05:57,900 plants to understand how to control them, where they become weeds. But it is also interesting to understand 64 00:05:57,900 --> 00:06:03,750 them because they're fascinating in their own right. These are evolutionary enigmas 65 00:06:03,750 --> 00:06:09,420 and little is known about the life history of many of the species. Some of the exotic ones 66 00:06:09,420 --> 00:06:14,700 are fascinating. One of the better known is roughly zikr, which produces 67 00:06:14,700 --> 00:06:20,610 the largest flowers in the world. They can grow to over a metre across. And this extraordinary 68 00:06:20,610 --> 00:06:26,010 plant is an Endou Fetich hollow parasite. So not only does it not have 69 00:06:26,010 --> 00:06:31,290 leaves or chlorophyll like this or a banky, but I've shown you it also lives inside 70 00:06:31,290 --> 00:06:36,690 the tissues of its hosts. Only emerging when it produces these gigantic 71 00:06:36,690 --> 00:06:41,940 blooms on the rain forest floor. So if ever there was a botanical enigma, this 72 00:06:41,940 --> 00:06:47,920 is it. 73 00:06:47,920 --> 00:06:53,080 So I've left my guard and I'm in the pass of Kozlow Park. And gets to say Park is run 74 00:06:53,080 --> 00:06:58,720 by the city council, you probably hear the road in the distance. It's not that far away from here. 75 00:06:58,720 --> 00:07:03,760 That's the ring road around a very busy road in this park. If you can ignore that 76 00:07:03,760 --> 00:07:08,860 noise, it feels very tranquil. And there's lots of different parts of this park. This park 77 00:07:08,860 --> 00:07:13,960 has been allowed to become a really nice meadow. And I don't know what you can hear in this film, 78 00:07:13,960 --> 00:07:19,720 but I can see butterflies flying around. I can hear grasshoppers chirping. And it's what we think of as traditional 79 00:07:19,720 --> 00:07:24,810 nice meadow. And that means it has wildflowers in it. And I've got a few different ones show you. I don't 80 00:07:24,810 --> 00:07:29,860 know how well the camera will pick them up, but there's four on my hand here. This 81 00:07:29,860 --> 00:07:35,620 little Rev's one here is a red clover. The white one is an Upsidaisy. 82 00:07:35,620 --> 00:07:40,750 It's much bigger than the lawn daisies that grow in your lawn. Then there are two yellow ones. 83 00:07:40,750 --> 00:07:46,090 The slightly more feathery thing is at ladies bed straw. 84 00:07:46,090 --> 00:07:51,250 It smells quite nice there at the foliage and that's why it gets its name from. And this 85 00:07:51,250 --> 00:07:56,260 is eggs and bacon. It's a little bit of low growing yellow 86 00:07:56,260 --> 00:08:01,270 flower. So all four of these can be found in abundance here and lots 87 00:08:01,270 --> 00:08:06,370 of other flowers as well. So that's the question really. Why is it in a nice meadow like this? You've 88 00:08:06,370 --> 00:08:12,180 got all these wild flowers and it hasn't just it's not just the grass totally dominating. 89 00:08:12,180 --> 00:08:17,650 And that's I to think about it a bit more detail how the yellow rattle is playing a crucial role in maintaining 90 00:08:17,650 --> 00:08:22,750 these wild flowers. Okay, so what's going on in the magic? Well, what happened with 91 00:08:22,750 --> 00:08:27,850 a lot of our traditional machos is people starts to fertilise them, added fertiliser to 92 00:08:27,850 --> 00:08:32,980 get more yield. Get more grass. No, the grass the farmers would harvest and use it to feed their 93 00:08:32,980 --> 00:08:38,800 animals. I mean, artificial fertilisers became available. Farmers leapt on those and started fertilising 94 00:08:38,800 --> 00:08:44,410 pastures. Now, what happens when you do that is that grass, grass and the wildflowers 95 00:08:44,410 --> 00:08:49,870 you can think of as being two different strategies, if you like. And it turns out if you don't fertilise 96 00:08:49,870 --> 00:08:54,970 them too much and you let animals graze them or you perhaps move them once a year, then 97 00:08:54,970 --> 00:09:00,520 these two things can grow together side by side. But when you start to fertilise, the grass 98 00:09:00,520 --> 00:09:05,740 becomes really dominant. And it's a bit like playing the game rock, paper, 99 00:09:05,740 --> 00:09:11,590 scissors. And if you can imagine that the grass starts playing the strategy paper 100 00:09:11,590 --> 00:09:16,900 and the wildflowers are stuck with a strategy rock. And as you know, if you play that game when paper 101 00:09:16,900 --> 00:09:22,170 meets rock, paper always wins. So every time these two things meet, 102 00:09:22,170 --> 00:09:27,580 a paper beats the rock and gradually the grass just takes over. And the poorer wildflowers 103 00:09:27,580 --> 00:09:32,650 are wiped out. Now, if you're familiar with that game, you will know 104 00:09:32,650 --> 00:09:38,480 what you need in a game of rock, paper, scissors for it not just to become as boring as that is a pair of scissors. 105 00:09:38,480 --> 00:09:44,700 And that is what the Hey Russell represents. So let's just cut some and we'll see what happens. 106 00:09:44,700 --> 00:09:49,930 So this is now my hay rattle. This is it. Once it's setting, see these empty pods 107 00:09:49,930 --> 00:09:55,780 and listen. That is the rattling and that's why it's called. Hey, Russell. 108 00:09:55,780 --> 00:10:00,880 So this is now playing strategy scissors. And of course, when scissors, me, paper, scissors, 109 00:10:00,880 --> 00:10:06,130 cut paper. So the Ryan and first the the hay rattle attacks the grasses and wins 110 00:10:06,130 --> 00:10:11,500 against the grasses. But the final flowers are still playing. Rock and scissors doesn't 111 00:10:11,500 --> 00:10:17,140 win against rock. In fact, it loses. And that's because this plant cannot parasitise 112 00:10:17,140 --> 00:10:22,600 the wildflowers. It can only parasitise the grass. And so now 113 00:10:22,600 --> 00:10:28,090 we have all three strategies. We have rock. We have paper. And we have scissors. 114 00:10:28,090 --> 00:10:33,400 And the three of them can actually live together very, very well indeed. Because no body 115 00:10:33,400 --> 00:10:43,550 has an absolutely winning strategy. And so that's how plants can play rock, paper, scissors. 116 00:10:43,550 --> 00:10:48,600 Today, we will learn a bit more about mistletoes, mistletoes or semiprecious, if he 117 00:10:48,600 --> 00:10:53,780 plans a semi parasitic plant is a plant that obtains some 118 00:10:53,780 --> 00:10:59,090 but not all of the necessary resources from another living and species like a tree. 119 00:10:59,090 --> 00:11:04,130 In the case of many mistletoes, a really interesting feature of mistletoes is 120 00:11:04,130 --> 00:11:09,290 the point of connexion to its whole street. Here you can see a drawing of 121 00:11:09,290 --> 00:11:14,390 a serious because he has grown no leaves a deciduous host tree. As many you can 122 00:11:14,390 --> 00:11:20,560 find across the UK. And then here you can also find an individual of mistletoe. 123 00:11:20,560 --> 00:11:26,550 Mistletoe is, of course, do have leaves and branches. But if we were to some in 124 00:11:26,550 --> 00:11:31,820 or you would see that in this part of this section where the branch of the whole story and the mistletoe 125 00:11:31,820 --> 00:11:37,160 come in contact is like in roots where you can find instead of that. So really interesting 126 00:11:37,160 --> 00:11:42,290 architecture. If you consume in here, you will be able to see it's planted with my 127 00:11:42,290 --> 00:11:47,630 finger. I'm showing you the whole storeroom. The Historium is 128 00:11:47,630 --> 00:11:52,670 a root like structure that the mistletoes developed when they first germinate upon the 129 00:11:52,670 --> 00:11:58,070 branch of the whole street. This structure allows the mistletoe 130 00:11:58,070 --> 00:12:03,980 to become a hemi. Parasite's Hemi comes from Greek means half to half parasites. 131 00:12:03,980 --> 00:12:09,680 This structure allows it to steal quote unquote, water and nutrients from the whole street 132 00:12:09,680 --> 00:12:16,730 water, nutrients that are, of course, come in all the way from the underground section of the tree. 133 00:12:16,730 --> 00:12:23,300 So they steal the water. They're still in nutrients and they carry out their own photosynthesis. 134 00:12:23,300 --> 00:12:28,370 But even then, they're not 100 percent efficient. And when that there was a paper that came out last year 135 00:12:28,370 --> 00:12:33,410 in Nature pointing out the fact that the first synthetic varieties of mistletoes is not 136 00:12:33,410 --> 00:12:38,750 as efficient as as many other plants that grows in Tree of Life. So perhaps instead of referring 137 00:12:38,750 --> 00:12:44,090 to mistletoes as healthy parasites, we should perhaps three quarter parasites, not 138 00:12:44,090 --> 00:12:49,130 any parasites. Well, I'm back where I started just to finish off this video. A huge thank you to 139 00:12:49,130 --> 00:12:54,230 Chris and to Rob for making those pieces. What I filmed introduction. I haven't even asked Chris to do 140 00:12:54,230 --> 00:12:59,530 it. Hadn't said that was really nice of him. And I did it with a unique taste. But if you look at that roughly, 141 00:12:59,530 --> 00:13:04,610 see a picture that popped up during his little piece, you'll notice it's not 142 00:13:04,610 --> 00:13:09,740 a photograph. It's one of his amazing paintings. And Chris is a very, very talented 143 00:13:09,740 --> 00:13:14,780 botanical artist, as well as knowing loads about plants. And his Twitter feed has lots of his 144 00:13:14,780 --> 00:13:19,970 lovely pictures. If you're not already following that. So parasitic plants come in different shapes 145 00:13:19,970 --> 00:13:25,160 and forms. We have the hemi parasites. We have the full parasites who really are the vampire plants. 146 00:13:25,160 --> 00:13:30,260 And the Ryan unfussy my lawn. Well, I've only got a few plants here. No, you can see them. Whether my cameraman 147 00:13:30,260 --> 00:13:35,360 can feed Matt as the big dark brown seed pods and if managed to recover a bit, they didn't like 148 00:13:35,360 --> 00:13:40,910 that very, very dry period earlier in the year. But they are setting seed now. And I'm hoping 149 00:13:40,910 --> 00:13:46,040 that by having them in my lawn, they'll help other wildflowers to establish. I've also 150 00:13:46,040 --> 00:13:51,140 got mistletoe actually in my apple tree at the back of the garden. And what happened this year? We noticed it completely 151 00:13:51,140 --> 00:13:56,300 come unplugged from the tree and it's fallen out. And I don't know. But I think that might be the 152 00:13:56,300 --> 00:14:01,460 host tree rejecting the mistletoe plants. Do you have a kind of primitive immune 153 00:14:01,460 --> 00:14:06,920 system they are able to recognise when they're being invaded by something that isn't themselves 154 00:14:06,920 --> 00:14:12,380 and take action against it? So like all of us in the face of disease and parasites, we're not helpless 155 00:14:12,380 --> 00:14:17,480 in the face of them. We've got weaponry and we can fight back. Anyway, I hope you enjoy hunting 156 00:14:17,480 --> 00:14:36,720 for vampire plants yourself. See you next time. I'm back on Bolaji.