Plant classification

The article plants, people, planet provides a brief overview of the relationship between plants, people, and planet Earth, and the set of articles that address this topic while the article plant-people science discusses the transformation of this topic into a formal science. The article plants for people provides a variety of lists of economically and historically important plants. The article plant-people Big History gives a long-term historical overview of the coevolutionary relationship between plants and people. The plant-people timeline provides a chronological overview of major events and transitions in the relationship between plants and people.

Three inter-related articles address the possibility of establishing a science of plants and people – a scholarly systematization of our knowledge about the relationship between plants and people. The investigation begins with a study of classification as a means of establishing the grounding principles for such a study. A second article then investigates plant classification not in the formal scientific sense as plant taxonomy, but in the multiple ways that we classify plants according to purpose. The final article, plant-people science, tackles directly the problem of establishing a new academic discipline, the scientific study of plants and people. The article plants and people provides an introductory context. For a more conventional account of the human-plant relationship as one of plant utility see the Wikipedia article on the human use of plants.

Background

The recorded study of plants – which we call botany, botanical science, or plant science – began in antiquity with the study, by an academic or priestly class of people, of the different plants that were used for medicinal purposes. This formal interest in the medicinal use of plants was inherited from prehistory as sacred knowledge possessed by highly respected individuals such as a shaman or medicine man of some kind. Lists of medicinal plants were shared across language groups, and it was these plant inventories that allowed plant information to be communicated across cultures.

In the classical world a scientific curiosity and desire to distinguish between plants moved academic interest away from the medicinal properties of plants towards their formal grouping, or classification, according to the physical similarities and differences that existed between the plant kinds themselves.

Relationships

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. This is a critical and systematic study of the kinds of plants that exist and the relationships that exist between them.

Our intense scientific focus on the relationship between plants themselves has closed our eyes to two other major kinds of plant relationship.

First, the relationship between plants and their wider environment, which we now know as plant ecology. Though a crucial aspect of traditional plant knowledge from the earliest times, it is amazing that the study of plants in relation to their environment only gained scientific traction in the 20th century.

Second, our gradual awakening today to the global significance of a third kind of plant relationship – that between plants and people. To date, his relationship has only been treated in an ad hoc and unsystematic way.

Thus, there are three grand domains of plant relationship – all with the potential for scientific study. They are the domains implied by the title of this web site:

(a) plants and their relationship to one-another

(b) plants and their relationship to their surroundings (to their biotic and abiotic environment)

(c) plants and their relationship to people (plants and their relationship to human material and symbolic culture)

Relationship (a) provides the inventory that facilitates the study of (b), while (c), which is a subset of (b), is of current critical importance to humanity as we enter a new geological epoch, the Anthropocene, a time of unprecedented human influence on the natural world. There is some historical arbitrariness about the degree of scientific gravity that we have associated with each of these relationships. 

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

There is no existing formalization of the study of plants and people. The topic is currently treated as a hotch-potch of complexly connected ideas relating to agriculture, horticulture, forestry, ethnobotany, economic botany, and human culture in its many forms. It is this complexity that has inhibited the formalization and systematization of plant-people knowledge.

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

Plant classification today

We inherited from antiquity the idea of the species as a ‘natural kind’ existing in nature. Also, from antiquity came a legacy of about 1000 species descriptions – mostly those of Theophrastus, Dioscorides, and Pliny the Elder that appeared in the herbals of 1470-1670. The project of global plant inventory only began in earnest with the European Renaissance, accelerated by its systematization into the simple principles and procedures devised mostly by the great Swedish 18th century naturalist Carl Linnaeus at a time when plants were pouring into Europe in a phase of global European colonial expansion.

There were good 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. With a shared understanding of the species plant knowledge could join the body of recorded and collective 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 various uses – for food, medicine, religious ceremony and so on – but these classifications were grounded in human utility or interest not the plants themselves.

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.

Today, with the task of global plant inventory nearing completion it is now time for those interested in plant taxonomy to look beyond natural kinds and their relationships to one-another. 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 redirect 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, with 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 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 we attempt to, as it were, construct a new academic discipline – the science that studies the relationship between plants and people?

Formalization

The idea of making the study of plants and people an academic discipline can, at first, seem unusual until it is realized that scientific disciplines often arise in response to practical needs. Mathematics developed 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 this new discipline is, in principle, no more challenging than, 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 within the topic by reducing complexity and organizing informational content (systematization). This includes a set of clearly defined categories, properties, and relations facilitated by a technical vocabulary that simplifies and clarifies key concepts.

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 was transformed into plant science.

Social authority and respect for the discipline follows as the number of its professional associations and academic institutions increases.

The Mission

There are seemingly infinite ways of investigating the relationship between plants and people. The categories ‘food’, ‘medicine’, ‘agriculture’, ‘forestry’, ‘gardens’, ‘economic botany’, ‘plants illustrated on postage stamps’ etc. are all legitimate topics of study. But how do we classify them all? On what grounds do we prioritize, sift, and sort the myriad potential categories?

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, and an honest attempt to address the question is better than no attempt. We have to start somewhere.

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 – and that depends on not only the purpose, but the scale.

In principle, 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 provides a focus for the systematic development of ideas.

The article on classification noted that the contents of any classification – the items to be classified, the selection criteria used to arrange them into groups, and the arrangement of groups into a system of classification – the reasoning behind the further development of categories and principles of study . . . all are subordinate to the purpose.

The ‘purpose’ therefore constitutes a foundational statement of broad objectives: a mission statement to guide the new discipline. The purpose is stated dogmatically here – but will be explained later.

The Purpose

The purpose is like a temporary hypothesis: the most efficient and informative framework of ideas on which to build the knowledge that makes up the discipline, bearing in mind that it is open to endless interpretation and modification as knowledge accumulates.

                                                                        Purpose

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 between the Industrial Revolution to the present day (centuries).

Historical principles

Scale

The articles on Big History and history in 10,000 words isolated those factors considered of greatest historical significance (and explanatory utility) for 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 simple 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 broad political, economic, and cultural factors. Short-term history (decades or less) is mostly about particular places, particular events, and particular people. Expressed (over)simply, there is a transition, from environmental history (millennia) to economic and cultural history (centuries), to politics (decades).

The study of plants and people is most efficient when starting from the broadest historical context before focusing on spatiotemporal detail. The place of concern thus becomes planet Earth and the timescale, for convenience, that of life on Earth (millennia), taking note of pertinent preconditions.
The logical space that exists for the relationship between plants and people ranges between, at one extreme, local and individual people and plants to, at the other extreme, the relationship that exists between all humanity and the totality of vegetation.

The logical timeframe that exists for the human/plant relationship can range between individuals in the present moment to all humanity over the period of its existence.

As a matter of explanatory expediency it makes sense to begin with an overview of the Big History, Big Picture context: the relationship that exists between all humanity and the totality of vegetation over the period that humanity has lived on Earth. We must begin by viewing the relationship from the perspective of millennia.

Principle – a contextual account of the relationship between plants and people begins with a Big History, Big Picture explanation of the relationship that has existed between all humanity and the totality of vegetation on Earth over the period that humanity has existed.

Principle – the broad context of the human-plant relationship is framed primarily within the spatial scale of planet Earth and its time of human occupation

Having established the broad parameters of time and space for our initial study, we now need to find the appropriate long-term historical categories that will act as lenses to focus our attention on the place of the plant-people relationship over the broad sweep of human history. We can look for assistance in this endeavour from the students of Big History – as human history from both the context of universal history, and the history of humanity – as well as the views of more traditional historians who have examined human history over the long term.

Key selection criteria

Having established the spatiotemporal scale of interest as the period of human history on planet Earth, then the initial task of classification is to determine those key factors that have influenced the course of human and plant history.

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, with social organization being:

‘. . . the bundle of technological, subsistence, organizational, and cultural accomplishments through which people feed, clothe, house, and reproduce themselves, explain the world around them, resolve disputes within their communities, extend their power at the expense of other communities, and defend themselves against others’ attempts to extend power.’

The kinds of social organization we encounter depends primarily on energy availability, capture, and use.

Energy was used ever more efficiently by developing increasingly sophisticated and mutually-enhancing mental and physical technologies (tools): the mental tools of collective learning included not only education, but science, arts, social values, and public administration, and the physical tools of mining, construction, manufacture, transport, communication, and trade.

Energy (and resource) availably relates largely to geography, with ready access leading to economic and social growth . . .  new forms of organization, increasing social complexity, and increase in population size and density. Larger and more organized societies used the benefits of scale to dominate or absorb other societies. But  changes in social organization change the nature of the geographic challenges – as when improved transport systems overcome the tyranny of distance.

Needless to say, this is a reduction or oversimplification of human history, but it provides a sufficient framework of ideas with which to adequately address our Mission. 

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

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 over millennia:

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

Traditional history
Following the discussion in the article history in 10,000 words, the account on this web site follows the conclusions of Harvard professor of history Ian Morris by treating social organization as the most illuminating lens through which to view human history. If we want to understand why human history unfolded as it did then a good place to start is by studying what has influenced social organization and its increase in complexity. 

Though modes of social organization depend on both cultural factors (like religion, science, systems of value, governance etc.) and material factors (resources, especially energy, technology, communications systems). Over the long term it is material factors, especially geography, that have mattered. Energy powers both physical and intellectual activity. Critical here are not only energy availability and its kind (mostly as plants and plant-based fossil fuels), but also its modes of capture, and use as determined by changing historical circumstance as when improved transport systems remove the tyranny of distance as changes in social organization and technology change the nature of geographic challenges.

Flourishing societies establish new forms of organization with economic expansion and the increase in social complexity associated with populations that expand in numbers, size, density, division of labour, and economic diversity. 

In general, larger and more organized societies have used the benefits of scale to dominate and absorb other societies as increasingly sophisticated technology facilitated the development of communication and transport systems that encourage trade.

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

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

The categories we use for the spaces that these plants occupy tend to fall into the three broad categories of park, garden, and field although there are many sub-categories and variants including plantations, orchards, vineyards, market gardens, nurseries, meadows etc.

Environment, society, economics

The approach has been to tackle the topic of plants and people with a clear statement of the purpose or objective of the of the history together with its spatiotemporal scale. 

It is now possible to build a grouping of categories to act as reminder of the major factors influencing human history. Their interconnection precludes the development of a simple hierarchy and the possibility of alternative groupings or systems of classification.

As a historical account, the declared purpose or objective is set within the spatiotemporal context of millennia of human existence on planet Earth. Human history is then interpreted through the lens of changing social organization whose degree of activity is determined by energy (resource) availability, technology, and use.  

Social organization is influenced by the development of both mental and physical tools (technologies) – both the mental tools of religion, science, public administration etc., and the physical tools of mining, manufacture, construction, transport, communication, and trade.

These factors influencing human history are many and they are connected in complex ways. The notion of ‘sustainability’ considers these factors in relation to three internationally accepted and interconnected broad headings that encompass the concerns of a globalized human community: environment, society, and economics. It is a recognition that the future growth of economies and societies must take place within the constraints of the environment in which they exist. It is under these three pillars that the future management of the global community is best understood. Most of the key criteria of social organization cut across all three pillars.

Energy

Population (number, extension, density)

Geography (historical influence)

Technology

Transport & communication

Incidental criteria

This long-term approach focuses attention on those historical factors of greatest consequence for human history, which provides a perspective from which to assess the many plant-human topics that are of potential of interest. Though a study of the plants depicted on ancient Greek vases, or postage stamps have fascination within their own context, they have no place in a Big History account of plants and people.

Synergies

Explanations are like classifications whose purposes, objects, properties and relations are all expressed in the most economical way possible – with the selected objects, properties, and relations all determined by the purpose of the explanation.

The most useful explanations are the ones that use categories that express general ideas in the clearest, most succinct, and efficient way, the obvious examples being the generalities, principles, and laws of science.

We try to capture a world of meaning in as few words as possible but even as our minds differentiate, focus, group, and prioritize our experience, we know that all things are connected. We trade-off simplicity and accuracy and always the provision of a  representations of the world is open to interpretation. But this is no reason to give up on the process of refinement and revision.

Having selected social organization as prior to other historical factors we must then determine those related categories or concepts that have the greatest historical explanatory power: they are the factors that, when operating in unison, give social organization its momentum.

Principle – historical synergies are the connected factors that most efficiently help explain a particular  idea – and which, when operating in harmony, provide collective momentum

There are various key ideas that interactively contribute to the enhancement of social organization, but they are predicated on the presence of sufficient energy and resources, they are: growth of population and economy, globalization, collective learning including science and technology, transport and communication, complexity.

Principle – the most useful category for gaining insight into long-term human history is social organization. Associated with this are the factors that have been used to determine the four major phases of history: physical environment, mode of communication, technology (especially transport and communication systems); energy type, source, and use; diet; group size within the total population.  

Plant-People Big History

It is now time to draw the threads of this discussion together.

History is here treated like an explanation in the form of a classification whose objects, properties, and relations depend on the purpose of the explanation and the scale of time and place under consideration.

A formal study of the relationship between plants and people is most coherent and informative when first considered within the broadest possible framework of time and place – the history of humans and plants on planet Earth over the period of human existence.

At this scale the human influence on plants is most informative when considered in terms of changes in plant distribution, their species composition, and biomass – the most notable being the relative proportions of wild and cultivated plants, and the human impact on cultivated plant genetics.

This is a big picture investigation – a Big History account of the key factors that have influenced the course of human and plant history (key selection criteria), the way these have played out over time (the four phases), and the implications for the future.

Four phases

Using key selection criteria appropriate to this scale of history, a Big History account of the plant-people relationship can be readily divided into four phases, described elsewhere in more detail as Natura, Agraria, Industria, and Informatia.

A contextual brief summary follows: 

Natura

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).

Agraria

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.

Industria

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).

Informatia

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.

Human influence on plants

The long-term influence of humans on world vegetation is most effectively explained and measured in terms of plant distribution over the surface of the Earth (especially the relative proportions of wild and cultivated species), the changes in species composition, changes in biomass over time, and the human influence on the genetics of cultivated plants.

Plant distribution

How best to categorize the vegetation that clothes the surface of the Earth?

The most obvious distinction is between cultivated and naturally occurring plants.  But vegetation may be categorized in various ways: economic, biogeographic, botanical, and so on.

Vegetation types
The broadest practical category or unit of measurement reflecting human influence is the distinction between the wild plants (natural vegetation with minimal human influence such as that in national parks and wilderness areas), and the cultivated plants traditionally recognized as those of agriculture, forestry, and horticulture although 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).

Historically the rate of land appropriation for cultivated plants has been related to the development of agriculture, European colonial expansion, and the size of human population that it services.

Biogeography
Traditional global biogeography has divided the world into biomes that fail to recognize human impact, although the notion of anthromes is now gathering support.

Biomass

One useful way of quantifying human use of plants is through measures of HANPP (human appropriation of net primary productivity). Modern techniques like satellite imagery provide a current means of accessing information but historical data is lacking.

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.

Principle – the long term impact of humans on plant life can be summarized in terms of the human-influenced changing plant distribution, including its species composition, vegetation type, and biomass. Most important here is the replacement of wild landscapes and plants by cultural landscapes of cultivated, and mostly man-made, plants (cultigens). The latter plants are mostly the luxury culinary and medicinal plants, the land-hungry plants of agriculture, horticultural crops, timber trees, ornamental plants and weedy plants that have escaped from cultivation into nature and cropland.

TABLE OF CONTENTS

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