Antony Funnell
Imagine a future full of solar rose gardens that generate electricity and robot-tree hybrids that grow into whatever shapes we need. Antony Funnell ventures to the frontiers of plant science to meet researchers who believe the power of botanical organisms has long been underestimated.
By his own admission, Magnus Berggren has killed an awful lot of roses in his quest to turn simple flowers into a source of power.
'Most of the materials for the devices that we injected into the plants actually were so toxic, the plants didn't survive,' says Berggren, a professor of organic electronics at Linkoping University in southern Sweden. 'But now we have chosen materials that we know cope well with plants.'
Those materials include a type of conductive liquid polymer capable of passing through the vascular system of the rose, effectively hard-wiring it.
'What we have focused on in our science is to make conducting wires, batteries or capacitors inside a stem,' he says.
'We have done electrodes in the leaves and step by step we are distributing components, electrodes and wires into the plant, so we basically approach a situation where we start, maybe, to connect a solar-to-electricity conversion system inside a plant.'
The ultimate goal, according to Berggren, is to create a system which siphons off some of the power generated by the plant during the natural process of photosynthesis. But while he and his team have already proven that it is possible to build a functioning electronic circuit within a rose bush, the dream of going further and creating an energy-producing solar garden is still many years away.
'We are talking about an application scenario that lies maybe 20, 30 years ahead,' says Berggren.
'What I think we could actually do is generate electricity inside the plants to power, for instance, a sensor or some other device that regulates the growth process in a plant. Or we could perhaps power up our mobile phone or something like that. But that's more on the demonstration or prototype level.
'What this will end up with in the end, to be honest I'm too naive to speculate on that. What we are trying to do in our group is to see how far we can stretch the idea.
'If we can use this as an energy conversion system in large scales in the future it will depend very much on the performance we can achieve. We have to remember that the solar cell that we have on the roof today, they have a power conversion efficiency of around 20 or 30 per cent. So we have to do this in a very efficient way if it's going to compete with that. But it's an interesting idea, and it certainly opens up a new pathway where electronics can end up in the future, that's for sure.'
Robots interacting with plants as they grow
In the German city of Paderborn, computer scientist Heiko Hamann has also been exploring ways of using technology to modify and regulate plants.
Professor Hamann is one year into a four-year project called flora robotica, which is funded by Horizon 2020, the European Union's Framework Programme for Research and Innovation.
The focus of flora robotica is to develop 'symbiotic robot-plant bio-hybrids'—essentially a system of small robotic devices fixed to a plant that interact with it as it grows.
Hamann sees applications for such technology in agriculture, where robotic sensors could be used to help farmers respond more accurately to a plant's needs and therefore speed up growth. But he also sees potential for creating what he calls bespoke 'architectural artefacts'.
'What we have in mind is more like having robots interact with plants and have them grow in different ways to what we see right now,' he says.
'We want to extend the natural growth processes to some artificial growth processes by imposing different stimuli on the plants and then grow certain shapes, for example. And that's where architecture comes in as an application. The idea is that some human user can input a desired shape and then we would use our robots to direct the growth of the plants and to actually grow that particular shape.'
The ability to grow trees into desired shapes, says Hamann, could have associated environmental benefits.
'Until now we grow our trees and then, with a lot of waste energy, we cut them and transport them. We think: what if you just grow wood in the shape that you require for your construction, maybe even at the spot? You have a house that is growing along with your needs.
'These robots are, we believe, the best way to interact with plants and also to gain a better understanding. Basically our robots can serve as a communication channel between plants and human beings.'
'We are not the only living systems who are smart'
The notion of plant-human communication in such a context might seem entirely functional: a new way for humans to once again exercise their dominance over the natural environment. However, a growing number of researchers believe the potential power and sophistication of plants have long been underestimated.
Professor Paco Calvo at the University of Murcia in Spain is one of the co-founders of a multi-functional research institute called the MINT Lab, one of the first centres of its kind, designed to further the relatively new field of plant neurobiology, the study of plant 'intelligence'.
'The easiest way to get into plant neurobiology is by thinking of the cognitive sciences in comparison,' says Calvo.
'Go back to the '70s, the '80s, and when we were talking about cognitive science we wouldn't talk about psychology or neuroscience or linguistics or anthropology, we were talking about the sum of all those disciplines. It was an attempt to better understand what cognition consists of by putting together the methodologies, and a little bit the same happens with plant neurobiology.'
In that vein, the MINT Lab brings biologists together with philosophers to explore what forms of intelligence plants exhibit, and in turn, what a better understanding of their capacities and capabilities might mean for the future.
'I'm not quite that happy with trying to provide the definition of intelligence, of plant intelligence, but maybe because I don't even know what animal intelligence is. I mean, as soon as you provide the definition somebody is going to show up a dozen counter-examples. I'd rather talk about particular capacities, competencies, and then we might discuss whether that deserves the label of intelligence or not.
'Think of sensory motor coordination, as we know happens in animals, or perceptual capacities, or goal oriented behaviour, basic forms of learning, of memory, decision-making, problem-solving. If animals can do all those things we're happy with the label intelligence, right? We say animals are intelligent.
'When plants do it, it seems we are in a whole different business. Why? Plants are able to do that, to make decisions, solve problems, learn, memorise. Well, let's deal with it. We are not the only living animals who are smart or living systems who are smart.'
The social side of plants
Forest ranger Peter Wohlleben has been something of a media hit in Germany with his best-selling book The Hidden Life of Trees, in which he spells out his belief that trees are social entities that not only grow together but communicate with each other in different ways.
It's a controversial idea on the surface, but he's not alone in coming to that conclusion. One who shares his belief is Suzanne Simard, a professor of forest ecology at the University of British Columbia. Simard has spent many years studying what's called mycorrhizal symbiosis: the theory that various forms of fungi that grow around the roots of trees act as a sort of pathway for communication, almost like neurons in an animal brain.
'These mycorrhizae function by growing through the soil and picking up nutrients and water and bringing them back to the tree. It's a symbiosis because they live together in a root tip, and it's mutualistic because the tree provides photosynthate in return for these nutrients and water that the fungi gather up from the soil.
'The reason that we say that the trees can communicate is that these fungi, some of them can actually link trees together. So a fungus that is associated with one tree can grow through the soil and link up with another tree, provided that fungus is compatible with both of those trees. Even if the trees are of a different species, if they have a compatible mycorrhizal fungus, they can link up.'
According to Simard's research, trees use their mycorrhizal networks to exchange a whole range of biochemical information, from how much photosynthate they have to how rich they are in nutrients.
'I consider it communication because there is behaviour adjustment. There are changes in the trees before they send the communication, the ones that are sending the communication, and then it results in a behaviour change by the trees that receive that piece of information. When you have those kinds of responses and effects and there's an information transfer that results in these big behaviour changes, to me that is communication.'
Crucially, argues Simard, there is also evidence of intent. 'We often reserve that word for human beings, where we have intention of changing some sort of pattern or behaviour, but in this case the trees, you could say that they also have intent in the sense that the trees that are sending the messages are conveying that there is some kind of environment or occurrence that is affecting their behaviour and that they need to, or have a want to, send that information to their neighbours.
'We know that big old trees—we call them mother trees—will communicate with seedlings that are their kin or their kids and make room for those kids compared to seedlings that are strangers, and they are doing this through their mycorrhizal networks.
'In that sense the mother trees are providing a favourable environment for the regeneration of their own kin, their own genes. That is one example of forests behaving like a family. There's other experiments where we've shown if we injure that mother tree experimentally that she will also send defence signals out to other seedlings around her.'
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