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Plant-people taxonomy

Classification is about relationships. When we speak of plant classification, we think of the biological classification that we learned at school: the ordering of the plant kingdom into species that are grouped into genera, families, and so on. But this study of the relationship between plants and plants is just one of several major kinds of plant relationship.

There are three grand domains of plant relationship that are implied in the title of this web site.

(a) plants and other plants

(b) plants and the planet (plants and their biological and physical environment)

(c) plants and people (plants and human culture)

Relationship (a) provides the inventory that makes (b) possible. While (c), a subset of (b), is of special interest to us right now as we enter a new geological epoch, the Anthropocene, a time of unprecedented human influence on the natural world.

It is now time to redirect the intellectual energy that was once tied to plant-plant relationships towards the relationship that exists between plants and people.

There is currently no formalization of the study of plants and people, the topic treated mostly in an ad hoc way using a hotch-potch of loosely connected ideas based mostly around the use of plants by native peoples (ethnobotany) and industrial society (economic botany).

This article explores the possibility of developing a scientific classification of the relationship between plants and people – a taxonomy that can potentially become as rigorous as that currently used to explore the relationship between plants and other plants.

Conventional classification

We inherited from antiquity the idea of the species as a ‘natural kind’ existing in nature. Also, from antiquity came descriptions of about 1000 of these natural kinds. But the project of global plant inventory only began in earnest with the European Renaissance, the development of its principles and procedures being associated with the great Swedish 18th century naturalist Carl Linnaeus at a time when plants were pouring into Europe during a phase of colonial expansion.

There were good historical reasons why the serious scientific study of botany began with plant description and classification. Without an agreement among its practitioners about what philosophers call its ‘natural kinds’ (real things existing in nature) botany was in chaos. Once there was a consensus on the units, kinds, or species then it was possible to move on to other matters.

Most importantly species were treated as existing in nature; they were not creations of the human mind.  Without this communally accepted foundation of species, all else would fall into confusion. Once there is a shared understanding of a species then it is possible to accumulate shared knowledge about it as a form of collective or communal learning.

Species, once considered created by God and therefore immutable, were arranged by humans into groups based on their similarities and differences. This process, it was believed, was an investigation of the order placed in nature by God. ‘Deus creavit, Linnaeus disposuit’ Linnaeus liked to say — God created, Linnaeus organized. After Darwin these similarities and differences were attributed, not to God, but to descent with modification from a common ancestor.

There were, of course, all kinds of folk classifications – the arrangement of plants according to their use as food, medicine, and so on, but they were grounded on human utility or interest rather than nature itself.

This narrow understanding of plant classification (plant taxonomy) is in many ways a relic of the past. In principle, the scope of plant classification is much wider – it includes all possible plant relationships – not just those that exist between plants and other plants.

With the task of global plant inventory is nearing completion it is now time for those interested in plant taxonomy to look beyond natural kinds.

This phase of global plant inventory is now, after nearly 500 years, nearing completion. The count of seed plants currently stands at about 350,000 species, all neatly ordered by our best computers crunching out classifications based on hypothetical evolutionary trees built on information gleaned from plant DNA.

It is time to direct our energy and resources into a new kind of taxonomy.

The new plant classification

Today the pressing issue confronting humanity is not the relationship between plants and plants, but the relationship between plants and people . . .  the reciprocal interaction between human society in all its complexity, and on a global scale, and the Earth’s vegetation, both wild and cultivated.

But we have no formal taxonomy for this relationship – no set of generally accepted principles and categories that can be used to build a systematic body of scientific knowledge that can then be used to guide policy making and the future management of the Earth’s vegetation. Instead, we have a set of loosely connected topics from disciplines as disparate as anthropology, economics, agriculture, medicine, ethnography, fine art, and so on.

What problems do we confront when attempting to establish such a classification – when we attempt, as it were, to establish a new science – the academic discipline that studies the relationship between plants and people?


The idea of making the study of plants and people an academic discipline can, at first, seem ridiculous until it is realized that scientific disciplines often arose in response to practical needs. Mathematics arose out the problems of engineering, building construction, surveying, and military arts; biology out of medicine and animal husbandry; chemistry out of metallurgy and dyeing; economics out of the management of trade and resources in both business and the home. The complexity of the topic is, in principle, no more challenging that, say, anthropology, which is a respected subject on campus . . . and what need could be more pressing than the future of humanity?

Let’s get going.

An academic discipline is a domain of accumulated specialist knowledge with theories, concepts, and research methods that promote problem-solving by reducing complexity and organizing informational content (systematization). This usually includes a technical vocabulary (which simplifies concepts for exponents of the discipline) that includes clearly defined categories, properties, and relations.

Social authority and respect for the discipline then follows with an increase in the number of its professional associations and academic institutions. This, in broad terms is how descriptive botany, as the study of plant kinds, emerged from medicine in the mid 16th century, before it expanded into increasingly wider plant studies in the 18th and 19th centuries as botany. Then, with the admixture of more environmental and commercial components it has become known as plant science.

The article examining what we mean by ‘science’ concluded that there is no unique ‘scientific method’ that separated science from other disciplines – no clear demarcation between science and other forms of knowledge. It is the collection of evidence from all possible sources to achieve the best possible explanation.

We can begin examining and adopting the general principles of scientific procedure before applying the specific principles of taxonomy.

The following table lists these principles and how they can be used to formalize the study of the plant-people relationship.

Systematization – academic disciplines comprise communities that develop their own agreed internal categories of study. A body of facts or truths systematically arranged to show the operation of general laws. For our purposes this will be pursued initially as a ‘table of contents’

Classical categories – the categories under investigation must be as clear, distinct, and closely defined – by necessary and sufficient conditions (classical) rather than family resemblance (fuzzy)

Terminology – precisely defined terms that facilitate clear communication within a specialist area of learning

Empirical – the most rigorous possible application of reason based on intensive experiment and observation

Universal principles – related to the above This gives us a practical starting point for our human understanding of plants. We wish to know what applies to all plants at all places and all times. Then we can determine what applies at particular places, particular times, and particular instances.

Historical principles

Historical analysis entails selection, organization, and simplification (reduction) of history’s teeming variety into underlying principles. Though historical causes may be multifactorial, parsimony is paramount. The problem is not whether explanations are reductionist or not (explanations are almost universally reductionist) but whether the degree of reduction is sufficient to answer the questions posed.

Time & place

The articles on Big History and history in 10,000 words pointed out that the factors we consider as being important in history depend on the time scale being considered. Just as different objects come into focus when we view the world on different spatial scales, so too do the important causes of historical change vary as we zoom in and out of different temporal scales. This point is easily missed: what we regard as important in history will depend on the spatial and temporal scales under consideration.

In very general terms, the longer the time frame (millennia) the more important become large impersonal forces like geography. Over the medium-term (centuries) we tend to focus on change due to political, economic, and cultural factors. Short-term history (decades or less) is mostly about particular places, particular events, and particular people. Loosely, there is a transition from environmental history (millennia), to economic and cultural history (centuries), then politics (decades).

The study of plants and people must start from the broadest historical context before focusing in on spatiotemporal detail. The place of concern thus becomes planet Earth and the time-scale, for convenience, that of life on Earth (millennia).

Principle – the broad context of the human-plant relationship is framed within the spatial scale of the world over the temporal scale of life on Earth – historical forces operating over millennia

Major long-term themes

Big History, at the scale of millennia and beyond, has revealed four key historical determinants:

1. the crucial role of energy in all systems
2. the origin of new properties at particular scales of material organization
3. the presence of critical conditions needed to cross physical thresholds.
4. the emergence of increasing complexity in spite of the overall trend to degradation (entropy)

And three key factors critical to human history:

1. access to, and control of, resources
2. growth in human population
3. increase in social complexity (social organization).

But what factors does traditional history regard as paramount?

Principle – the broad context of the human-plant relationship is framed within the context of the use of plants as an energy source, first for food and then for the raw energy of fossil fuels that would help power the growth of economic activity, technology, the human population, and the increasing complexity of social organization

Four phases

Based on these criteria the history of the plant-people relationship is intimately tied to human history as a whole and can be readily divided into four phases described in more detail elsewhere as Natura, Agraria, Industria, and Information.

First was the phase (Natura) of nomadic hunter-gatherers in the Upper Palaeolithic which lasted from about 315,000 BP to around 12,000 BP (these dates are still a matter of keen academic debate) when small tribal groups of 10-20(-100) people lived within wild nature at a time when the world human population peaked at around 3 million (Morris 2015). Universally the plant diet was quite varied, consisting mostly of wild greens, fruits, seed, and root vegetables and the meat of hunted animals. Some additional indirect energy was needed to support individual and collective lives – such as that obtained from fires or embedded in the materials used for clothing, and so on. Social activity was achieved mostly using human muscle, so this was a form of existence that benefitted from energy conservation, with minimal possessions, the use of simple domestic and hunting tools, and the highly developed skills of bush craft. The combined total of food energy and social energy was roughly 1.5 to 2 kcal/capita/day (Morris 2015). The migration of prehistoric hunter-gatherers, walking out of Africa to occupy the world, took about 60,000 years sourcing wild animals (ultimately dependent on plant energy) and wild plants as food for muscle-power. Hunter-gatherers placed little emphasis on political and wealth hierarchies but accepted gender hierarchy and violence (Morris 2015).

Second, was the phase of settled farming communities (Agraria) with their domesticated plants and animals which, during the Neolithic Agricultural Revolution, arose independently in 6-12 centres of civilisation (the exact number is debated) across the world, the first appearing about 13,500 years ago in the ancient Near East. Most people in these communities were engaged in farming based on cereals. Grains were a concentrated source of energy that could be stored for year-round use. Some settlements thrived and grew into Bronze Age cities that became trade centres for even larger human groupings of nations and empires.

Effectively governed communities with large populations took advantage of new technologies made possible by their scale of operation in a series of changes that increased the complexity of social organisation. The sedentary existence facilitated population growth in hierarchically governed urban societies displaying many of the characteristics we associate with the cities of today: a division of labour, coinage, monumental architecture, private ownership, sophisticated legal and economic systems, art, written records etc. as proportionally fewer people worked on the land.

In and around the Bronze Age cities there were now specialised (often enclosed) social spaces that contained cultivated plants, spaces that served different social functions and which have persisted to the present day: fields, public parks, avenues, orchards, vegetable and market gardens, vineyards, gardens – both domestic and royal – and the formal plant decoration used around administrative blocs, temples and burial sites. It was during the Bronze Age interaction of trade, diplomacy and military conquest that occurred between Mesopotamia, Egypt and the Aegean during the third to second millennia BCE that ‘. . . gardens emerge as distinctly meaningful spaces’ (Stackelberg 2013).

The increase in social organization was made possible by the surplus energy from plant and animal domestication and the human population multiplied from a few million people at the dawn of the post-Ice-Age Agricultural Revolution about 10,000 years ago, to 400 to 500 million around 1550 CE at the dawn of phase 3. The combined total of food energy and social energy needed to produce, store and distribute the grain and sustain communal activity had now increased fourfold to around 6-8 kcal/capita/day (Morris 2015). Agricultural societies no longer depended on wild plants but used the energy provided by cultivated plants to feed the muscles of man and domesticated beast over a period that lasted about 10,000 years.

Third was the Modern Era (Industria) which lasted about 500 years from around 1550 to 1950 as a time of rapidly increasing social complexity – the advance of science, technology and medicine that was combined with population growth, industrialization, democratization, the development of nation-states, and the global connectivity that flowed from the Age of Discovery and European colonial expansion. This accelerated social change took place when the muscle power of humans and domesticated animals was supplemented by using the concentrated plant energy found in fossil fuels, providing the social energy that powered industry and manufacturing. Industrial agriculture used sophisticated machinery to boost food production in what was, in effect, a second Agricultural Revolution as people moved from farm to factory, from toil on the land to work in the expanding cities. The number of people working in agriculture fell dramatically in technologically developed countries – from over 90% at the beginning of this period to less than 5% today (see Roser 2019).

It was fossil fuels (fossil plants) – first coal (a convenient replacement for the rapidly diminishing supply of timber fuel) and then gas and oil – that were the drivers of increasing global connectivity and social complexity. The outcome of Industria was a world that aspired to energy-hungry Western lifestyles that consume over 200 kcal/capita/day (Morris 2015), a hundredfold increase over that of hunter-gatherers. Plant-based energy use increased from about 38 kcals/person/day in 1800 at the start of the Industrial Revolution to around 92 kcals/person/day in 1900, and 230 kcals/person/day in 2000 (Cook 1971).

Phase four (Informatia) followed in the wake of the devastation of two WWs as economic recovery gathered pace around 1950. Increasingly sophisticated science and technology facilitated globalisation and the more efficient extraction of planetary resources that produced unprecedented economic and population growth – the Great Acceleration – as the world population soared from 2.5 billion in 1950 to 6 billion in the year 2000. It had taken about 200,000 years for the human population to reach 1 billion around the year 1800 and then, fired by fossil fuel social energy, only 200 years more to reach 7 billion.

Cities expanded upwards with the advent of skyscrapers, and outwards as domestic houses and gardens multiplied to form sprawling suburbs. In 1800 about 3% of the world population lived in cities but by 2017 this had increased to 55% (Index Mundi World Demographic Profile 2018) as more land was appropriated to provide the food needed to feed the growing population.


The reason why we currently have no generally accepted classification for the relationship between plants and people is its multifaceted and multidisciplinary nature.

The article on classification noted that the contents of any classification are subordinate to their purpose. The purpose of the classification is its foundation, so we must recognize at the outset that any different opinions about purpose will have consequences that will permeate the classification as a whole.

Much of the complexity and abstraction concerning the relationship between plants and people may be resolved with a clear statement of what the classification is designed to achieve. This, though always open to alteration and improvement, provides a focus for the systematic development of ideas.

It also highlights potential sources of difficulty and disagreement. So, for example, if we decide to subsume the classification under the heading ‘plant utility’ – how are we to organize and decide on potential plant resource categories? And, even if there can be common agreement on these, how are they to be grouped and ranked? Where do we fit ‘food’, ‘medicine’, ‘agriculture’, ‘forestry’, ‘structural materials’, ‘cultural ornaments’ in such a system – which topics are, as it were, unique, and which are subsets of other topics?

Faced with the reality of these complications it is easy to understand why there is no currently accepted plant-people taxonomy, and why the attempt to create such a taxonomy might seem foolhardy. But the urgency of the situation cannot be denied, so we have to start somewhere.

We must begin with a generally accepted statement of purpose before establishing the general principles of the classification.


The most informative and parsimonious classification of the reciprocal influences that exist between plants and people considered over the long term (millennia), but with special consideration of the cultural developments that occurred from the Industrial Revolution to the present day (centuries).

This generalized objective needs to be organized according to the subject’s major areas of interest.

Human influence

The long-term influence of humans on world vegetation can be best explained and measured in terms of the historical change in plant species composition and biomass over the surface of the Earth, a process strongly related to plant cultivation and the accelerating process of genetic modification.

Though the three categories of agriculture, horticulture, and forestry are a handy first point of differentiation between cultivated plants it is more historically and economically informative to recognize six groups: cereals and staples (agriculture); herbs, spices, aromatics, and medicines (culinary, medicinal); horticultural crops (plantation crops like cotton, coffee, sugar;  the nuts, fruit orchards, and vegetables of market gardening; and grapes of viticulture); timber trees (forestry); and ornamental plants (gardening). This has led to a further and recent category of plants that have escaped from cultivation to invade both cropland and nature (naturalized plants). 

The following table provides a broad historical context for these plant categories.

Prehistory – Medicine, Culinary Herbs & Spices, Aromatics – these plants have been used throughout history and are strongly associated with religious traditions and ceremony. Culinary herbs and spices are now globalized ingredients of international cuisine. Plant medicine, the original source of specialist plant knowledge (that led eventually to botanical science), has given way, in part, to the production of synthetic medicines

12,000 – 4,000 BP – Agriculture – the domestication of plants and animals in settled communities arising independently, and at different times, in about 12 centres across the world. Agriculture intensified during the period of European colonial expansion and was followed by the Industrial Agriculture that followed the Industrial Revolution, along with a rapid increase in the sophistication of plant breeding and gene technology. Agriculture, based around staple crops, continues to expand to feed the growing world population

Terminology – precisely defined terms that facilitate clear communication within a specialist area of learning

Empirical – the most rigorous possible application of reason based on intensive experiment and observation

18th-19th centuries – Naturalized plants – a consequence of the former categories, the naturalization of plants escaping from cultivation gathered momentum with the global dispersal of plants that occurred with the spread of agriculture and domestic gardening during the period of European colonial expansion. Biosecurity addressing undesired plant introductions is a contemporary practice.

Selection criteria

All classifications must establish the key selection criteria on which their groupings are formed.
This exercise begins with the assumption that this relationship is most informatively discussed as one evolving in time and that, in the first instance, this time extends over millennia.

In the interests of historical parsimony and the subjectivity in the choice of selection criteria a decision must be made about those factors most influential in determining the course of long-term (millennia) human history. Without such a grounding it is not possible to investigate the historical role of plants.

Following the discussion in the article history in 10,000 words, the account on this web site follows the conclusions of long-term historian Ian Morris by treating social organization as the most illuminating lens through which to view human history. The kinds of social organization we encounter depends primarily on energy availability, capture, and use. Energy availably relates largely to geography with free access leading to new forms of organization, increasing social complexity, flourishing societies along with increases in population size and density. Larger and more organized societies have used the benefits of scale to dominate or absorb other societies. Changes in social organization change the nature of the geographic challenges – as when improved transport systems remove the tyranny of distance.

The mode of social organization also influences social values. Cultural development also rests on energy availability and its technological application.

Time scale, social organization, population size and density, geography, energy, technology,


Major human plant dependencies developing before the emergence of Homo sapiens c. 350,000 BP

. . .
1 March 2019 – first published on the internet
16 August 2022 – beginning substantial revision


Four phases of human history – all driven by plant energy
Image Courtesy of Rob Cross – 2017

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