1. Introduction
Plants can see. They can count and communicate with one another. They are able to react to the slightest touch and to estimate with extraordinary precision. Such statements, put baldly, seem almost fanciful not to say exaggerated to the point of falsity. Yet while some of these abilities have only recently been identified by botanists, the evidence for others is known to anyone who has the slightest acquaintance with plants– and that must surely mean almost everyone.
David Attenborough Footnote 1Many would agree that plants – such as trees, shrubs, grasses, ferns, flowers, mosses – are more than just ‘objects’ or ‘things’,Footnote 2 in the common sense of those words.Footnote 3 Yet, in private law, in many – if not most – civil law jurisdictions,Footnote 4 this is not the case. Within private law, the word ‘object’ commonly does not only refer to inanimate objects, such as scissors, screenplays, stairs, skyscrapers, and satellites. Plants, too, together with animals and other non-human lifeforms, have long been ‘objects’ in private law.Footnote 5
To be sure, across the world and throughout history, different societies and communities have (had) different views regarding plants. For example, ‘Eastern’ religions have been considerate of plant life ‘for millennia’, Marder indicates;Footnote 6 and, as Calvo and Lawrence write, ‘[a]nimistic societies in pre-Christian Europe or in different parts of the world today’ regard plants as ‘entities with potency and meaning’, and various Indigenous cultures – such as the Māori, certain Native American groups, Indigenous Amazonians, the Inuit, and Indigenous peoples of subarctic Canada – view plants as, for instance, ‘kin with a shared heritage’ or ‘“persons” with souls of equal standing’.Footnote 7
The private law distinction between humans and objects, common in many, if not most, civil-law countries, is particularly sharp in European civil law societies.Footnote 8 While a sharp distinction between a human being and an inanimate object still seems perfectly understandable, such a sharp distinction between a human being and other living beings – including plants – is arguably less defensible today. The division between humans on the one hand, and all other beings on the other, stems from the age-old idea, prominent in the history of Western thought,Footnote 9 that humans are separate from ‘the external, natural world’,Footnote 10 which exists for humans to appropriate;Footnote 11 as well as from the idea that humans – endowed with (supposedly) uniquely human characteristics such as intelligence, language, and reason – are the only lifeforms that can be granted legal subjectivity.Footnote 12
However, as a result of scientific discoveries such as the theory of evolution by natural selection, the supposed uniqueness of humans has been challenged more and more convincingly. It has become common scientific knowledge that humans are more related to, as well as more similar to, other animals, and even to plants, than had long been assumed, and, furthermore, that humans are far more dependent on the web of nature than was previously known.
Law, commonly changing in the wake of scientific discovery,Footnote 13 has followed suit. There are several interesting and important legal debates that are relevant to the question of the legal status of plants. The animal rights debate is one, and the more recent debate on Rights of Nature (RoN) is another. Since the adoption of the first RoN law in the United States (US) in 2006,Footnote 14 this approach has become more and more popular. As Kurki writes, ‘[i]t is increasingly taken for granted that rivers and other natural entities can be legal persons and right holders’.Footnote 15 While we sympathize with the RoN movement, given its attempts to incorporate ‘Nature's rights … into a broader rights framework for governing the planet sustainably’,Footnote 16 we are also conscious of the (possible) drawbacks to this approach.Footnote 17 These vary from ‘conceptual deficiencies’Footnote 18 to the contention that, say, a tulip tree (Liriodendron tulipifera) can never reciprocally recognize the rights of others or have legal responsibilities.Footnote 19 Furthermore, RoN requires many advocates, in both the ‘nature's rights’ model (‘anyone can speak for nature, but is not obliged to’), as well as the ‘legal personhood’ model (‘specific guardians are obliged to represent the ecosystem at all times’).Footnote 20 In the courts there have hitherto been some ‘arbitrary’ results, ‘ungrounded in any meaningful criteria’.Footnote 21 Also, there may be serious political hurdles to clear in certain jurisdictions when it comes to bestowing something as lofty as rights on non-human organisms such as plants. The above does not suggest that efforts to extend RoN to non-human organisms should be abandoned, rather, that additional approaches are worth exploring.
In this article we suggest an additional approach to a changing legal status for plants, one that confronts the aforementioned designating of plants as ‘objects’ in private law. We build this approach on another recent legal development pertaining to animal welfare and biodiversity protection: the de-objectification of the animal in private law.Footnote 22 In recent years, the long-standing and sharply drawn private law distinction between humans and non-human beings has become blurred in several jurisdictions. Over a dozen European countries have amended their civil codes either to state explicitly or to imply that animals are, in fact, quite different from objects.Footnote 23 Bernet Kempers explains that a new private law category has now emerged, ‘that lies somewhere in between the person and the thing’.Footnote 24
Some scholars have argued that the placing of animals in such an in-between category is purely symbolic, in that it does not readily appear to have material legal effects on animals.Footnote 25 However, Bernet Kempers cautions that:
the possible implications of the development should not be underestimated. Even though it is certain that the provisions that differentiate between animals and legal things do not vest the animal with legal personality, the new status may influence the way animals are being addressed in various areas of private law and can possibly be construed as a limit to the rights of persons.Footnote 26
Furthermore, as Burdon and Williams have noted, in the context of RoN, bestowing rights not only provides governmental protection but also visibility, changes in consciousness regarding the something or someone that has been given rights, and increased respect for that same something or someone.Footnote 27 The same could well be argued with regard to de-objectifying living beings in private law.
In this article we want to open the debate on de-objectifying plants. Based, inter alia, on recent scientific discoveries on plant sentience, what are some of the most important arguments for the de-objectification of plants in (civil law) private law? Plant sentience is relevant because sentience in some (or all) animals has been invoked in several jurisdictions as an important argument in favour of de-objectifying animals.Footnote 28 Other or additional arguments to support the de-objectification of animals have also been put forward: an animal's intrinsic value, or its dignity, or the fact that an animal is a fellow living being.Footnote 29
Plants, like animals, are different from inanimate objects. Yet, there appears to be no noteworthy consideration of that fact in private law. Academic legal scholarship appears to be incomplete on this issue;Footnote 30 to our knowledge there is no academic literature that considers the de-objectification of plants in private law from a policy-based approach – let alone any realization of such policy. We believe that, compared with the rights-based approach, which can in some ways be more consequential but also more controversial, the de-objectification of plants in civil codes presents a more accessible opportunity that is both meaningful as well as politically and legislatively feasible. It could influence the way in which plants are addressed in private law and protected by public law,Footnote 31 limit the rights of persons vis-à-vis plants, and increase the visibility of and respect for plants in the eyes of citizens. Subsequently, these developments might lead to better protection for plants on the grounds of their instrumental value to humans, and/or on the grounds of their own sentience, value, dignity, aliveness, and so forth.
To firmly root our argument, this article branches out as follows. Firstly, we discuss the de-objectification of animals in private law by considering several civil codes that distinguish animals from objects. This section is more doctrinal in nature, looking at black-letter law, parliamentary deliberations, jurisprudence, and legal scholarship.Footnote 32 Secondly, we present a brief overview of findings in scientific research on plant sentience in order to substantiate the argument that plants may also be said to possess sentience. This ‘auxiliary’ interdisciplinary use of the natural sciences, more specifically plant science, is relevant because it provides a scientific foundation for the policy and legal debates we hope to instigate.Footnote 33 Thirdly, we address some of the different ways in which the legal position of plants is currently discussed, in both academic legal literature and other relevant sources. Finally, we conclude by arguing that it is high time to seriously consider de-objectifying plants in civil codes,Footnote 34 based on the recognition of some degree of sentience in plants, as well as on other rationales.
2. De-objectifying Animals in Law
Before we consider the de-objectification of plants, we will look at its quite recent precursor: the de-objectification of animals in several European jurisdictions. Bernet Kempers explains that for animals a new ‘category that lies in between’ (human) persons and mere corporeal objects has materialized in private law.Footnote 35
As mentioned, this de-objectification is a clear break with long-standing Western legal tradition, in which a sharp distinction exists between ‘human culture and the external, natural world’.Footnote 36 In this tradition, only by appropriating animals and plants does a human bring those animals and plants ‘into the legal sphere’, where they subsequently become objects of property rights.Footnote 37 Presently and generally, Bernet Kempers writes, an animal in the eyes of private law ‘is entirely defined by its status as property’.Footnote 38 Burdon and Williams also summarize that ‘Western legal systems treat the environment and non-human animals as property that can be bought, sold and used by humans’.Footnote 39 Eskens notes that since antiquity, ‘pretty much all philosophers, theologians, legal scholars and politicians’ have adhered to the idea that humans are ‘the only creatures to which a State could have obligations’, as humans supposedly are unique beings, endowed with uniquely human characteristics such as intelligence, language, and reason.Footnote 40
Bernet Kempers writes that the relegation of animals (and, we might add, plants) to the status of things to be exploited is arguably one of the causes of the current climate and biodiversity crises.Footnote 41 The centuries-long reduction of animals and plants to mere objects in private law could thus be viewed as one of the noteworthy factors behind the materialization of the Anthropocene.
2.1. Legal Consequences of De-objectifying Animals in Private Law
The new in-between category that de-objectifies animals in private law is interesting for legislators, as it can acknowledge both the special nature of animals – because of their sentience, their dignity, their intrinsic value, or other reasonsFootnote 42 – as well as the needs of sectors that require the use of animals as objects (including buying and selling them), such as agriculture, biomedicine, and the pet industry.
Acknowledging in private law that animals are different from mere corporeal objects is not the same as vesting animals with legal personality and rights. Despite no longer being considered objects, animals can still be, and still are, legally exploited by humans. It has been argued, therefore, that de-objectifying animals in private law is merely a symbolic act. Jansen, for instance, refers to Article 3:2a of the Dutch Civil Code (DCC), which has de-objectified animals in Dutch private law since 2013.Footnote 43 Article 3:2a DCC states that ‘animals are not things’, but then immediately adds that ‘provisions relating to things are applicable to animals’.Footnote 44 In other words, according to Dutch law, animals are more than mere objects but, legally, they can be considered as if they are objects.Footnote 45 Jansen argues that the Dutch legislator thus immediately ‘takes away … what he gives’, and that such an in-between category, therefore, has ‘zero legal consequences’.Footnote 46 Similar objections have been voiced regarding the French de-objectification of animals.Footnote 47
Yet, it could also be argued that this new in-between category is, in fact, more than merely symbolic. Burdon and Williams’ arguments in a different context (bestowing actual rights) are, as mentioned earlier, also applicable to de-objectifying an animal or plant in private law; de-objectification could not only (help to) provide governmental protection but also visibility, changes in consciousness regarding the living being that has been de-objectified, and increased respect for that same living being.Footnote 48 As mentioned, Bernet Kempers states that de-objectifying animals in private law is not as meaningless as it might appear, for it can affect the position of animals within private law and function as a ‘limit to the rights of persons’.Footnote 49
In some divorce cases, for instance (such as in France and Belgium), animals have been considered separately from the other objects in a household based on the affectionate bonds humans can have with them.Footnote 50 In other divorce cases (such as in Germany and the Netherlands) animals have been considered separately from other objects in a household because of the animal's own interests – to assess, for instance, whether a party is equipped to properly care for the animal.Footnote 51 De-objectifying animals can also play a role in determining the compensation for ‘damage’, as well as in the context of executing seizure for debts.Footnote 52 Although many of these cases predate the establishment of an in-between category in the applicable civil code,Footnote 53 Bernet Kempers argues that creating such an in-between category in civil codes ‘might better be regarded as a consequence; a way to make a trend explicit that is already going on’.Footnote 54
2.2. Rationales for De-objectifying Animals in Private Law
Several European civil codes grant a special position to animals. The civil codes of Germany, Austria, Switzerland, the Netherlands, and the Czech Republic state explicitly that animals are not objects.Footnote 55 Civil codes of various other European countries (Lithuania, Hungary, France, Estonia, and Romania) more implicitly suggest a special position for animals.Footnote 56
The underlying reasoning varies across the different jurisdictions. The Portuguese Civil Code states that animals ‘are living beings endowed with sensitivity and subject to legal protection by virtue of their nature’.Footnote 57 In several other civil codes the sentience of animals is used as a rationale for de-objectification. The Belgian Civil Code states that animals have sentience (gevoelsvermogen) and biological needs.Footnote 58 In France, too, the Civil Code explicates animal sentience (sensibilité).Footnote 59 However, sentience is not always the rationale for conferring a special status on animals. The German Civil Code, for example, simply considers animals to be non-objects, without acknowledging any special capacities,Footnote 60 although the German Animal Protection Act does state that animals are our ‘fellow beings’.Footnote 61
With regard to the possible de-objectification of plants, the Dutch parliamentary debate on the de-objectification of animals is particularly noteworthy. In 2013, the DCC took inspiration from the German Civil Code for the addition of Article 3:2a DCC, according to which ‘[a]nimals are not things’.Footnote 62 The intrinsic value of animals, first recognized in the Netherlands in 1981, is the basis for this amendment.Footnote 63 During the parliamentary deliberations on the amendment, Gerda Verburg, who at the time was the Dutch Minister of Agriculture, Nature and Food Quality, received a question from sceptical members of the conservative-liberal People's Party for Freedom and Democracy (VVD). In an attempt at a reductio ad absurdum reminiscent of Thomas Taylor's Vindication of the Rights of Brutes,Footnote 64 they cynically asked whether perhaps a similar amendment should also be introduced for plants, while they were at it.Footnote 65 Verburg nipped this discussion in the bud by responding that ‘plants are living things, too. They are, however, not living beings with sentience. Plants should, therefore, not be equaled to animals’.Footnote 66
We submit that this position needs to be reconsidered. In the next section we argue that scientific discoveries, especially in recent years, have convincingly called into question the assumption that plants are not sentient beings. If sentience is one of the main arguments for de-objectifying animals in private law, then the de-objectification of plants would not be so absurd at all.
3. Rationales for De-objectifying Plants in Private Law
A number of recent findings in plant science require us to take the idea of plant sentience seriously. This section gives an overview of such findings and other relevant considerations. Firstly, we briefly discuss how crucial plants are for human life and wellbeing, that is, their instrumental value.Footnote 67 Secondly, we address ‘plant blindness’, a common characteristic of human beings. Thirdly, we present some scientific findings on a variety of behavioural expressions of plants that may be interpreted as expressions of plant sentience. Fourthly, we consider speculations on whether plants could possess their own form of intelligence. Finally, we briefly introduce alternative rationales for de-objectifying plants, should acknowledging plant sentience (let alone, plant intelligence) be considered a bridge too far.
3.1. The Instrumental Value of Plants
According to the botanist Timiryazev, plants are ‘the intermediary between … energy in the organic world and the sun, the universal source of energy’, facilitating animal life through the photosynthetic creation of oxygen and through ‘the energy of the sun stored up by the plant’ being consumed directly or indirectly by animals.Footnote 68 Plants have provided energy (fossil or ‘fresh’) ever since humans first learned to control fire.Footnote 69 They are the foundation of the entire food chain, and they are the source of many essential medicines.Footnote 70 The vertical growth of plants has been foundational for the ‘evolution of the brains and particularly the neocortices of our [arboreal] ancestors’, and therefore ultimately of human intelligence.Footnote 71 Plants increase the human attention span, reduce stress in humans, and aid humans in recovering from illness.Footnote 72 Traffic accidents occur less in streets that have trees, and suicide and violent crime occur less in urban environments with ample green spaces.Footnote 73 Many important scientific discoveries that became famous only after their application on humans or other animals were actually first made by experimenting on plants (such as genetics, cellular biology, and ribonucleic acid (RNA) interference).Footnote 74 Plants also absorb pollutants.Footnote 75 Some plants can even accumulate such high amounts of heavy metals, like nickel and lithium, that ‘agromining’ might have a bright future: plants as ‘hyperaccumulators’ could be used either to restore polluted soil or to harvest metal.Footnote 76 Last, but certainly not least, their capacity to remove carbon dioxide (CO2) from the atmosphere makes plants crucially important for humans (and other forms of life) in the Anthropocene.
Even though these and other arguments would support – and have already supported – certain forms of legal protection for plants on the basis of instrumentality alone, humans still tend to ignore the importance as well as the abilities of plants. This ignorance is so remarkable, considering the facts, as to warrant being called ‘plant blindness’.Footnote 77
3.2. ‘Plant Blindness’
Discoveries in plant science indicate that humans are not as justified as many (though certainly not all)Footnote 78 may think in placing themselves above plants in the grand scheme of things. Author and journalist Pollan writes that ‘only human arrogance … keeps us from appreciating [the] intelligence [of plants]’.Footnote 79 Mancuso and Viola also emphasize, in their book Brilliant Green,Footnote 80 the ways in which humans have for millennia looked down upon the plant world as being somehow less evolved. For example, Noah in the biblical tale did not find it necessary to take plants with him on the Ark;Footnote 81 Aristotle classified plants – which he considered to be ‘deficient animals’Footnote 82 – as having a ‘low-level soul’, which acknowledged the ability of plants to reproduce but not much more;Footnote 83 and Islamic religious art largely avoids the representation of sentient living beings, yet frequently features plants and flowers.Footnote 84 Even Linnaeus and other scientists of his time, when observing the carnivorous behaviour of certain plants such as the Venus flytrap (Dionaea muscipula), refused to acknowledge that such plants actually lured, trapped and ate animals, preferring instead a host of peculiar explanations such as that ‘the insects didn't die at all, … they chose to remain inside the plant of their own volition and for their own convenience’,Footnote 85 or that when trapped animals ‘didn't free themselves, it was because they were old or had chosen to die’.Footnote 86 Calvo and Lawrence write that ‘[u]ntil the nineteenth century, many scholars vehemently denied that plants were sexual organisms at all’. They furthermore refer to a 1981 study from New Zealand that ‘found that many children did not even consider an organism to be a “plant” unless it had flowers’,Footnote 87 something that, we believe, might also be apparent in the commonly used term ‘flora’ for plants both with and without flowers.Footnote 88
Constitutional law scholar Tribe writes that ‘[n]o one should suppose that this bias is a shallow one or that it can readily be eliminated’ as its ‘roots lie deep within the Western philosophical and theological tradition’,Footnote 89 and philosopher Marder writes that ‘[d]eep psychological resistance prompts us to dismiss the mounting scientific evidence that challenges readymade conceptual molds, into which plants have been slotted thus far, in favor of the inertia of habit and the comfort of “common sense”’.Footnote 90
Botanists have long had a name for this common attitude that humans have towards plants: ‘plant blindness’.Footnote 91 Botanists Wandersee and Schussler, Grosscurt writes, ‘concluded [that there is] a human incompetence, a blindness to vegetation that is comparable to color blindness’.Footnote 92 Darwin himself was already aware of this widespread plant blindness in humans. Although he thought highly of plants, finding them ‘the most extraordinary living things he had ever encountered’,Footnote 93 he was nonetheless reluctant to introduce his thoughts on the abilities of plants because he had already bruised the human ego with his theory of evolution by natural selection.Footnote 94
This tendency in humans is unsurprising given the fundamentally different evolutionary paths that plants took from animals (including humans). When comparing the earliest plant and animal cells, Mancuso and Viola write, one finds that those were ‘really very similar’.Footnote 95 Yet, generally, plants went on to lead lives rooted in the ground on a fixed location (becoming so-called ‘sessile’ organisms), while animals went on to lead ‘nomadic’ lives, moving around (‘motile’ organisms).Footnote 96 Thus, animals needed to be able to carry all their organs with them while plants evolved a modular body without ‘central, irreplaceable organs’, which is fundamentally different from the human and non-human animal body.Footnote 97 Also, because of their rootedness, as well as their relatively slow tempo of movement, plants appear to human perception to be almost completely immobile and thus inanimate – although sped-up visual recordings of plants clearly undermine that supposition.Footnote 98 These and other fundamental differences from animals help to explain why humans exhibit plant blindness.
On our planet, which probably began to turn green around 500 million years ago,Footnote 99 plants are still overwhelmingly dominant, growing on ‘every terrestrial environment’,Footnote 100 and composing approximately 80% of the biomass on Earth.Footnote 101 This dominance indicates great adaptability and thus in certain ways a ‘superior problem-solving ability’.Footnote 102
In the next paragraph we sum up several of the most important arguments that plant biology offers in support of plant sentience. This supports our conclusion that because plants may possess sentience, there should at least be a serious parliamentary deliberation on whether plants should be distinguished from mere objects in private law, in the same way that animals in some jurisdictions have already been distinguished.
3.3. Plant Sentience
A phrase like ‘sentience of plants’ may seem to belong less in an academic legal text and more in a work of science-fiction, such as The Thing from Another World (1951)Footnote 103 about an extraterrestrial vegetable lifeform bent on world domination; or The Happening (2008)Footnote 104 about plants conspiring to induce millions of people worldwide to take their own lives and, in doing so, alleviate the pressure humans exert on the natural environment. However, it is science proper, and not science fiction, that allows for the sentience of plants to be seriously considered by legal scholars, as is increasingly the case.Footnote 105 This influence of scientific discovery on legal thought makes sense, since – as Judge Barbara Jaffe said in court when she presided over a US case involving the grant of habeas corpus to chimpanzees (in that they are highly intelligent, self-aware, and empathic animals) – ‘the law evolves according to scientific discovery’.Footnote 106
In this subsection we will refer to a variety of scientific findings on plant behaviour. Whether the (intentional) behaviour of plants proves sentience is yet to be agreed. This was affirmed in a recent special issue of the journal Animal Sentience on plant sentience.Footnote 107 In this source Segundo-Ortin and Calvo argue that ‘there is still much to be discussed before it can be accepted that plants feel, but we would disagree with those who would rather deny the possibility of plant sentience altogether’.Footnote 108 The 29 commentary articles in the special issue demonstrate that whether plant sentience is accepted depends largely on how ‘sentience’ is defined and studied; for as long as methods of studying animal sentience dictate studies on plant sentience, the results will be dismissive.Footnote 109 Accepting the plausibility of plant sentience requires accepting the possibility that sentience does not necessarily require typical animal properties such as a central nervous system.Footnote 110 We concur with Segundo-Ortin and Calvo and acknowledge that there is a degree of uncertainty over plant sentience. Still, given recent findings in plant science, we consider that one should take seriously the possibility of plant sentience and its implications for private law.
Plants appear to have all five senses, just like humans, albeit in their own particular way.Footnote 111 On top of these familiar senses, plants have ‘at least fifteen’ other senses, such as the ability to ‘calculate gravity, electromagnetic fields, and humidity’ and the ability to ‘analyze numerous chemical gradients’.Footnote 112 When those chemical gradients indicate a pollutant, the plant roots ‘distance themselves as soon as possible’.Footnote 113 Certain plants such as Mimosa pudica (better known as the Shameplant, the Sensitive plant, or the Touch-me-not plant), can even react to being touched,Footnote 114 and in doing so ‘distinguish among different stimuli, and even change its behavior, no longer remaining closed once it learns that a stimulus isn't dangerous’.Footnote 115
This assertion that plants can learn was already supported by experiments in the 19th century with Mimosa pudica. At first, the plants closed in reaction to the heavy shaking that occurred when the cart in which they were transported was pulled along over the cobblestones in Paris, but after some time they remained open. Having learned that they were not in any danger, they no longer wasted energy ‘by pointlessly closing their leaves’.Footnote 116 Many plants can ‘acquire learned behaviors … in a matter of seconds’ and can ‘remember what has been learned for several weeks’.Footnote 117 Birch trees can even remember something they learned for up to five years.Footnote 118 Plants can recognize attacks by herbivores and react accordingly, for example, by ‘making their leaves indigestible or even poisonous to the insect aggressor’.Footnote 119
Plants sleep; the leaves of many plants fold inwards at night to reduce their nocturnal activity.Footnote 120 In fact, the correlation between the sleep movements of plants and darkness has invoked the suggestion that plants possess ‘an internal mechanism for measuring time’.Footnote 121
Many experiments in molecular biology are carried out by growing plants in transparent gels. This leads to the roots being constantly exposed to bright light (as opposed to the darkness of soil). The plant arguably becomes stressed, rapidly growing its roots in a vain attempt to reach darkness.Footnote 122
Plants can also recognize their own kin and take caution not to frustrate one of their own as they would other plants in the struggle for sunlight, water, and soil nutrients.Footnote 123 Examples include not overgrowing the roots of a related plant or, in a phenomenon called ‘crown shyness’, not interfering with their sunlight.Footnote 124 Through underground mycorrhizal networks,Footnote 125 stronger fir trees have been observed helping carbon-deprived kindreds by supplying them with carbon.Footnote 126
Plants communicate via a language, using chemical compounds: ‘each compound transmits precise information, such as warnings of imminent danger, or messages of attraction or repulsion, or something else’.Footnote 127 Calvo and Lawrence write that more than ‘1,700 different volatile cocktails’ in the plant language ‘lexicon’ have been identified, and that the behaviour of plants ‘can change dramatically as a result of the messages being exchanged’.Footnote 128
Recently, Khait and co-authors found that plants emit ultrasonic sounds, resulting in the first sound recording of tomato and tobacco plants.Footnote 129 The significance of these sounds, however, is still very much open for debate. Possibly, they are the equivalent of ‘bodily’ sounds one can also hear inside animals, such as bowel sounds, heartbeats, and flowing air.Footnote 130 What has been demonstrated is that plants can register sounds from their environment. When playing a recording of sounds emitted by leaf-nibbling caterpillars, Thale cress (Arabidopsis thaliana) responded by activating its chemical defence mechanism.Footnote 131 Recordings of wind and insect song did not cause this reaction, which suggests selective responses to sound.Footnote 132
Through their ability to communicate with other plants,Footnote 133 as well as with animals,Footnote 134 plants form partnerships with both plants and animals.Footnote 135 These partnerships may be mutually beneficial. For example, parasitoid wasps are attracted by chemical compounds that plants emit when attacked by herbivores.Footnote 136 Furthermore, some ants defend plants in return for nectar.Footnote 137 One may even entertain the thought that humans are in a partnership with plants that they take care of because they find those plants beautiful, delicious or otherwise useful.Footnote 138 As Attenborough phrases it, plants like soy, wheat, and rice ‘persuaded us to eliminate their competitors, cure their diseases, poison their enemies, and keep them well-watered even when other species faced drought’.Footnote 139 Benton writes that ‘[f]lowers, as has often been said, are the plant's way of enslaving bees, moths, bats, and other pollinating animals’.Footnote 140 Like certain animals, plants too can be deceptive in their partnerships. Orchids, for example, trick male insects into carrying around plant pollen without giving the insect something in return.Footnote 141 To be sure, ‘mere’ evolution by natural selection – as opposed to conscious cognition or active choice – has facilitated many of these phenomena.Footnote 142
It could also be said that plants can make ‘plans’ for the future by estimating risks and benefits and ‘investing’ accordingly – such as through the ubiquitous ‘escape from shade’ behaviour that plants exhibit: they spend a great deal of energy, which is risky, ‘expecting’ to end up with benefits (sunshine).Footnote 143 The philosopher Hegel observed with interest such behaviour in potato sprouts as he watched them ‘climb up the wall as if they knew the way, in order to reach the opening where they could enjoy the light’.Footnote 144
In short, as summarized by Mancuso and Viola, ‘plants eat without a mouth, breathe without lungs, see, taste, feel, communicate, move, despite lacking sensory organs like the ones we do’.Footnote 145 They ‘defend themselves from predators by using complex strategies’, ‘circumvent obstacles, help one another, can hunt or lure animals, move to reach food, light, oxygen’.Footnote 146
As noted earlier, whether all this is ‘merely’ (intentional) behaviour or actual sentience is still being debated. Then again, animal sentience and even human free will are still being debated. In the light of scientific findings, some of which have been mentioned above, the sentience of plants deserves at least to be considered as a rationale for their de-objectification in private law.
In the next two subsections we discuss other possible rationales for de-objectifying plants: one that goes further than plant sentience (plant intelligence) and some that could be accepted instead of plant sentience – the precautionary principle applied to plant sentience, intrinsic value (or dignity), and plants as fellow beings (or aliveness, or common sense).
3.4. Plant ‘Intelligence’
The question of plant ‘intelligence’ is more contentious than that of plant sentience, and we want to stress that intelligence is not a necessary condition for de-objectifying plants in private law (nor is it for animals, after all). It is nonetheless an interesting potential rationale for de-objectifying plants. Do (some of) the examples of plant sentience also imply intelligence? That depends upon, among other things, how prepared one is to see ‘intelligence’ in ways that differ from the day-to-day connotation the term has in its human context.
Bridle, in his 2022 book Ways of Being, argues that ‘many different kinds [of] intelligence … have been here, right in front of us, the whole time – and in many cases have preceded us’, and that ‘Western science and popular imagination, after centuries of inattention and denial, are only just starting to take them seriously’.Footnote 147 Bridle writes that ‘[i]ntelligence, it seems, is something physical and relational, not a wholly abstract process, but one closely tied to our being and doing’,Footnote 148 and that ‘plant intelligence, whatever it is, is plant-y’, something that humans will never be able to fully understand.Footnote 149 Marder points to certain authors’ ‘calls for judging intelligent behavior in non-human organisms based on the capacities of the organism in question’ and that, in this spirit, ‘plant intelligence refers to what plants can do as well as to their unique perspective, expressed at the cellular, organismic and environmental levels’.Footnote 150 He suggests adopting a ‘plant point of view’ when considering the (supposed) intelligence of plants, for he feels that the field of biology ‘must investigate the particular perspectives correlated with each distinct form of life’.Footnote 151
Such an understanding of intelligence – as something that comes in many forms and must be appreciated in the context of a particular species – has also been put forward in writings on animal intelligence. Primatologist De Waal tellingly titled one of his last books Are We Smart Enough to Know How Smart Animals Are? Footnote 152 Balcombe, writing about sentience and intelligence in fish, relays that ‘[t]he modern scientific field of cognitive ecology recognizes that intelligence is shaped by the survival requirements that an animal must face during its everyday life’;Footnote 153 and that one is to heed ‘the plurality and contextuality of intelligence, the fact that it is not one general property but rather a suite of abilities that may be expressed along different axes’.Footnote 154 Balcombe appreciates the species-specific characteristics of fish precisely because ‘they are not like us’, writing that ‘[t]heir different ways of being in the world are a source of fascination and admiration, and cause for sympathy’.Footnote 155 In the 16th century, Michel de Montaigne pondered: ‘The defect that hinders communication betwixt [animals and humans], why may it not be on our part as well as theirs?’Footnote 156
One needs to remain mindful of the possibility that ‘intelligence’ is projected by humans on processes that could be partially, mostly, or entirely ‘mechanistic’,Footnote 157 and that a more prudent interpretation of plant behaviour should not be cast aside too rapidly.Footnote 158 With animals, too, some scientists have been too keen to anthropomorphize their supposed intelligence, Darwin being an important example.Footnote 159 Alpi and co-authors express appreciation for the field of ‘plant neurobiology’ as ‘an initial forum for discussions on the mechanisms involved in plant signaling’, but warn of ‘superficial analogies and questionable extrapolations’.Footnote 160 As mentioned earlier, the science into ‘plant sounds’ in particular is far from settled.Footnote 161 Wohlleben was criticized for using language, in The Hidden Life of Trees, ‘that is strongly anthropomorphic and teleological’.Footnote 162 On the other hand, De Waal feels that ‘even in the case of [distantly related species], anthropomorphic explanations deserve serious attention’.Footnote 163 Calvo and Lawrence caution against ‘two extremes: the anthropomorphic tendency to see ourselves in things that are entirely unrelated, and the anthropocentric refusal to acknowledge continuities that exist between ourselves and other forms of life’.Footnote 164
Dennett, who came up with an interesting taxonomy of competences in living beings,Footnote 165 is sceptical of the supposed capabilities of plants, stating that plants do indeed have competence and intentional behaviour, yet lack ‘comprehension’.Footnote 166 He cautions that humans wrongly assume that just because our own ‘behavioral competence’ comes with comprehension, the intentional behaviour that plants exhibit thus also must come with comprehension.Footnote 167 Humans, Dennett posits, are ‘anthropomorphizing the plants … in order to understand them’.Footnote 168 Dennett, however, is also sceptical of comprehension in non-human animals, even in ‘“higher” species such as mammals and birds’.Footnote 169 This would mean that – to briefly return to considerations on sentience – if animals can be de-objectified on the basis of sentience, as has been done in various civil codes, Dennett's diagnosis that plants are competent but do not comprehend would not necessarily bar plants from being de-objectified.
In 1974, Feinberg argued that ‘all are agreed that plants are not the kinds of beings that can have rights’ as they have ‘no conscious wants or goals’ and thus ‘cannot know satisfaction or frustration, pleasure or pain’.Footnote 170 To be able to have an interest, Feinberg contended, a living being needs to have ‘at least rudimentary cognitive equipment’.Footnote 171 However, in the decades since Feinberg wrote this, plants (in the form of forests, for instance) have indeed been given rights.Footnote 172 Furthermore, one could argue, as Eskens does, that living beings have ‘interests’ when their behaviour shows effort.Footnote 173 Plants do arguably show effort in their behaviour and pursuit of their biological needs. Calvo and Lawrence write that plants exhibit ‘adaptive, flexible, anticipatory, goal-directed behaviour’,Footnote 174 and that they, like animals, ‘move through their environments, collecting information as they go’,Footnote 175 ‘deploying their evolved toolkit of sensory abilities and behaviours as they interact with the living and inert world around them’.Footnote 176 Plants, they write, ‘keep a constant eye on a number of parameters as they fluctuate in real time’, and may, ‘[a]fter judicious cost-benefit analyses’, ‘triage’,Footnote 177 and ‘decide where to invest their precious metabolic resources’.Footnote 178
As noted earlier, whether one believes that plants might possess intelligence is ultimately not crucial for our argument for de-objectifying plants in private law. After all, sentience could (and does) exist apart from intelligence, and sentience as such would still be ample ground for their de-objectification.
However, should accepting plant sentience prove to be a bridge too far for some legislators, there are still other possible rationales for de-objectifying plants in private law, which we discuss briefly in the next subsection.
3.5. Other Rationales for De-objectifying Plants in Private Law
Firstly, the precautionary principle could be applied to plant sentience. Remarkably, chemicals like histamine, serotonin, dopamine, and gamma-aminobutyric acid (GABA) – all of which function as neurotransmitters in many animals, including humans – are also found in plants, and quite possibly play a significant role in the electrical signalling in plants.Footnote 179 Countering the argument that sentience requires certain typical animal features such as a central nervous system or a neocortex, Browning and Birch argue that there is ‘no evidence against the possibility that similar subjective experiences can be generated by very different mechanisms’.Footnote 180 Our lack of understanding of this so-called ‘multiple realizability’ of sentience could support applying the precautionary principle.Footnote 181 Without absolute certainty, which will never be attained (not even when it comes to questions on human sentience, consciousness or free will), we should give plants the benefit of the doubt, in line with the precautionary principle.Footnote 182 Even while the debate is still raging, the findings from plant science strongly support the idea that plant sentience is a realistic possibility. Are we smart enough to know how sentient plants are?
Secondly, one could consider a plant's intrinsic value or dignity as a ground for distinguishing a plant from a mere object. In 2008, based on the available scientific evidence, a committee of the Swiss Federal Assembly considered the ‘dignity’ of plants, which, according to Pelizzon and Gagliano, can be regarded as ‘the first legislative initiative to mandate “moral consideration of plants for their own sake”’.Footnote 183 Mancuso and Viola view the Swiss initiative as one that lays the groundwork for future plant rights; it could then perhaps also serve as groundwork for the future de-objectification of plants.Footnote 184 Philosophically, the concept of intrinsic value, which as mentioned is important in the Dutch context, is too complex to do justice to in this article. However, it seems safe to say that, legally, in many jurisdictions, plants are already held to have intrinsic value. The 1979 Convention on the Conservation of European Wildlife and Natural Habitats (Bern Convention), for example, explicitly refers in its preamble to plants (‘flora’) as having ‘intrinsic value’.Footnote 185 The Convention on Biological Diversity (CBD) also considers plants to possess intrinsic value, albeit implicitly.Footnote 186 The point of view expressed in the Bern Convention and the CBD, which have been ratified by almost all eligible states, could arguably be grounds for de-objectifying plants in private law.
Thirdly, plants are not objects in the common sense of the word. The German Animal Protection Act, as mentioned, refers to animals as our fellow living beings. Plants surely are our fellow living beings, too. The very fact that plants are alive can thus suffice as a basic rationale for de-objectifying them. Common sense suggests that plants, being alive, are not objects or things. Why not acknowledge this in private law? At the very least, it would codify the expansion of the citizenry's moral circle of empathy and consideration.
4. Expanding the Circle
Singer describes the historical development of human morality as an expanding circle: as (and in so far as) people ‘progressed’, they kept expanding (although also often retracting) their sense of consideration for and altruism towards people and entities other than their own individual self.Footnote 187 Darwin, too, in his Descent of Man (1871), wrote that the circle of ‘sympathies’ around people's own personal self continued to grow as time progressed.Footnote 188 Consequently, these developments in morality often translated into law.Footnote 189 As it expanded, the circle came to include more and more (groups of) people, human institutions, and animals. Most of the academic legal literature on expanding the circle to cover plants has focused on rights of plants or RoN, which is why some of this literature, as well as other relevant sources, will be discussed in the following paragraphs.
The concept of plant rights, like animal rights, is still in its infancy in Western jurisdictions. As mentioned, Marder writes that ‘Eastern’ philosophies ‘have been at the forefront of protecting plant life for millennia’ and might offer ideas for Western debates.Footnote 190 In European parliamentary discussions, plant rights have been considered only sporadically. In 1993, a member of parliament for the party GroenLinks (Green Left) in the Netherlands asked: ‘Who can defend the rights of plants, animals, and future generations, if not the government that should concern itself with these interests in the light of the common good?’.Footnote 191 Tribe wonders if people will want to afford rights to plants as they would to animals.Footnote 192 Marder, on the other hand, claims that expanding the circle to plants would not be ‘a radical break’ with current practices, but ‘a relatively minor adjustment’, a ‘fine-tuning’.Footnote 193
The ability to suffer or experience pain has also been offered in support of the position that (some) rights should be given to plants. Marder writes that ‘sentience and the ability to feel pain’ was the yardstick that suggested that (certain) animals should have the Arendtian ‘right to have rights’.Footnote 194 Tribe noted in 1974 that ‘[s]ome research even suggests that plants exhibit electrical and chemical reactions which are functionally analogous to pain’.Footnote 195 This has been suggested in various studies, including the 2023 ultrasonic sound experiment mentioned earlier, in which the sounds of stressed plants (after cutting or drought) appeared to be different from those of healthy plants.Footnote 196 Again, it is still uncertain whether those sounds can indeed be likened to utterances of pain.Footnote 197 Draguhn, Mallatt and Robinson state that ‘plants do not possess the molecular and structural machinery for pain generation’.Footnote 198 Petruzzello, too, writes that plants ‘do not feel pain as we members of the animal kingdom understand it’, although she stresses that ‘it seems that many plants can perceive and communicate physical stimuli and damage in ways that are more sophisticated than previously thought’.Footnote 199
In a 2023 study, plant signalling responses to injuries were visualized.Footnote 200 One consideration mentioned in the (biological) literature about future rights pertains to experimental testing on plants; the suffering induced by experimental testing on animals was, after all, an important factor in the struggle for animal rights.Footnote 201 As mentioned earlier, plants possibly experience stress when grown in transparent gels for biological research purposes. Being aware of their possible susceptibility to stress, the important question in relation to plant rights is whether, therefore, plants can be said to ‘suffer’, and, if so, whether humans care to expand their moral circle of empathy and consideration as a result.
Aside from some trials during the Inquisition where plants like fennel and garlic were believed to be accomplices of witches and therefore put on trial,Footnote 202 there have been hardly any instances where the (intrinsic) rights of plants themselves have been considered judicially. However, the rapidly proliferating RoN movement deserves attention in relation to plants. While some cultures and ontologies have a long tradition of recognizing RoN, even Western legal systems, which at first sight seems rather unwelcoming to non-humans, may now expand their circle by the granting of legal personhood, legal standing and/or representation through a board or trust to non-human individuals or collectives.
Despite RoN being far from uncontested,Footnote 203 the first examples of RoN (often also covering plants) have now been brought into existence, whether constitutionally,Footnote 204 legislatively,Footnote 205 or judicially.Footnote 206 Attempts to grant legal personhood to individual plants so far have largely been unsuccessful. For example, the Belgian Tribunal de Première Instance Francophone in Brussels denied the admissibility of 82 individual trees as plaintiffs in a climate case.Footnote 207 However, wild rice (Zizania palustris), ‘manoomin’ in the Indigenous Ojibwe language, was granted ‘inherent rights to exist, flourish, regenerate, and evolve’ in a 2019 tribal law of the White Earth Nation in the state of Minnesota.Footnote 208 This law protects the wild rice itself, its ‘freshwater resources’, as well as the ‘habitat of the rice’.Footnote 209 When the rights of the wild rice are violated, a lawsuit can be brought, with manoomin being the ‘the real party of interest’.Footnote 210
However, with far-reaching rights, such as the right to habeas corpus for chimpanzees mentioned earlier, it is difficult, if not impossible, to form an analogy between animals and plants: chimpanzees are highly self-aware and autonomous creatures, which have a ‘theory of mind’.Footnote 211 They have a notion of time and know that when they are imprisoned today, they will or can still be imprisoned tomorrow, which leads to suffering.Footnote 212 These characteristics, which were put forward as legal arguments in the court cases regarding chimpanzee standing, are not proven to be common in all animals, and also do not appear to be present in that way in plants.Footnote 213
Several authors, mindful of the ‘slippery slope’ argument, stress that the discussion of the rights of plants need not frighten people into thinking that someone who picks a flower could someday be charged with a criminal offence. Biochemist Koechlin says that we can keep eating and using plants, but that humanity merely has ‘some’ responsibility towards plants.Footnote 214 People, according to Koechlin, violate plant dignity in certain specific circumstances, such as genetically manipulating plants to be sterile so corporations can keep selling new specimens, or patenting plants.Footnote 215 Also, Koechlin believes, ‘plants should have some degree of independence regarding their adaptation and propagation, as well as the survival of their own species’.Footnote 216 Koechlin and co-authors furthermore have proposed ‘the Rights of Plants’ in several theses – known as the ‘Rheinauer Theses’ – which form the most elaborate proposal for rights of plants that we have come across.Footnote 217 They vary from the right not to be baselessly subjected to ‘[m]ethods and strategies that cause sterility’, to the right to survival as a species, to the right not to be patented.Footnote 218
Koechlin and co-authors state that ‘[p]lants are not objects’;Footnote 219 they ‘are living beings’.Footnote 220 We agree with these two theses, as has hopefully become clear. Yet, unlike Koechlin and co-authors and other voices mentioned in this section, we do not argue for rights of plants, but for de-objectifying them in private law.
5. Conclusion
Plants are fascinating organisms. Their instrumental value alone is immense, since they facilitate most animal life on Earth, form the basis of our food and energy chains, absorb CO2 and certain pollutants, and ameliorate our daily lives in myriad ways. For eons now, plants have existed on this planet in a manner that is foreign to animals in general and humans in particular, and we should thus be mindful not to anthropomorphize them. Nonetheless, there is ample indication that humans have underestimated and undervalued plants for a long time and in many ways, and that their value goes beyond just the instrumental.
In the more than 150 years since On the Origin of Species was first published, public perception of animals has undeniably changed. We now know that humans, animals, and plants share the same ‘lowly origin’.Footnote 221 This realization eventually trickled down more and more into law. Since 2004, over 1,000 animal protection laws have come into force in the US alone, ‘a number that rivals all of the animal protection laws enacted in American history prior to 2000’.Footnote 222
As we have argued, scientific discoveries about the various abilities of plants are causing our perception of plants to change, too. Another expansion of our moral circle could therefore include plants, by de-objectifying them in private law. Acknowledging that plants are living organisms – either with or without sentience and/or intrinsic value and dignity – rather than mere objects/things, would not necessarily lead to the bestowing of rights on plants. As mentioned above, de-objectifying animals in civil codes never necessitated fundamental changes to animal exploitation. There is no reason to believe that de-objectifying plants would be a legal Trojan horse that would make gardeners unemployed or force violin makers to continue their practice underground.
However, it would not be a dead letter either. From jurisprudence, it follows that the upgraded position of animals in civil codes causes judges to pay more attention to the wellbeing of the animal at stake. Equivalent to what Burdon and Williams write regarding bestowing actual rights, one could well say that de-objectifying plants in private law could not only (help to) provide governmental protection, but also an increased visibility and awareness of and respect for plants.Footnote 223 Bernet Kempers points to the noteworthy implications of de-objectifying animals in private law, such as influencing the way in which private law addresses animals, as well as regulating what human persons may or may not do with (certain) animals.Footnote 224 Similarly, this could serve numerous instrumental purposes for plants. Possibly, the legal de-objectification of plants could lead to, for instance, better protection of specific individual plants,Footnote 225 wider impact across entire plant species or even ecosystems, perhaps through the germination of a Plant Act as an equivalent to the various pieces of animal-related legislation.Footnote 226 Furthermore, the acknowledgement in private law for plants would contribute to the broader spirit that also feeds the calls for plant rights and Rights of Plants.
As such, for those who argue for meaningful steps towards incorporating non-human life into law, putting plants in the ‘in-between category’ could serve both as an inspiration and as a potential building block for later developments around plant rights and RoN in a broader sense. It could open up the conversation and broaden the legislative and political horizon. For those who are more sceptical of actual plant rights and RoN, the de-objectification of plants in private law could serve as a middle road. After all, amending a provision in the civil code is a feasible step to take, as the path for such an amendment has already been paved by the process of de-objectifying animals. Placing plants in the ‘in-between category’ in private law would not be scientifically, politically, or legally radical; and it would create possibilities without obligating anything. It would merely plant a seed, which then might blossom into something fruitful, or wither in infertile soil.
Considering the arguments for plant sentience mentioned above, it is peculiar that plants are still commonly seen as practically inanimate phenomena – not much more indeed than the ‘(corporeal) objects’ central to property law – that are not worthy of our consideration. Acknowledging in private law that plants are different from mere objects (or things) would to us seem to be in concurrence with science, and it would at least symbolically reflect an evolved and grown-up understanding, on the part of the citizenry, of the special worth of vegetable forms of non-human life – forms of life, incidentally, that make it possible for us to be alive in the first place and with which we share a common ancestor.
Acknowledgements
A rudimentary version of this article was written in 2019 as a Research Master paper by the corresponding author. For fruitful discussion, valuable suggestions for improvement, and encouragement, we thank Jonathan Verschuuren, Phillip Paiement, Arie Trouwborst, Floor Fleurke, Michael Leach, Edwin Alblas, Laura Burgers, Han Somsen, Ximena Arenas Orbegozo, and Jan van Laarhoven. We also wish to thank the three anonymous TEL peer reviewers for their constructive, stimulating, and instructive comments. Any errors remain our own.
Funding statement
Not applicable.
Competing interests
The authors declare none.
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