The chores of the April-garden are put off by the constancy of spring showers. A gardener’s skill is put to the test by the vagaries of the season which determine the needs of the plants. The spring bulbs such as tulips are peaking while fallen tree limbs of winter are yet to be gathered. The sudden explosion of the yellow-flowered forsythia reminds the gardener that soon the fire-storm of weeds will over take his best laid plans. All of a plantsman’s plans are waylaid by the irresistible enticements of new plant varieties, colors and forms found at local garden centers and nurseries. Every gardener lives to add just one more plant to his or her landscape palette. In gardening there is no end to addition, multiplication, division and weeding. There is not enough time to manage the change a-foot in April’s garden and no days more to be added to the list of work. The frantic sense of impeding incompletion is off-set by the thrill of this year’s show. Gardening is a race against time.
In this race to get the eternal work of gardening done are plant species which time and experience has shown to hinder and mar our attempts at artistic perfection that we call beauty which inform our senses. Invasive plants and pests spring up and compete with unwary, inexperienced gardeners. The weeds win when order disappears and randomness reigns supreme; the gardener wins when patterns in design and relationships of species are maintained. Some landscape literati know that garlic mustard spritely blooming and the soon-to-become-ruthless early growth of multiflora rose, bespeaks of endless war against the invaders for years to come. Perhaps the frosts of early April have kept the insects at bay, but in the warmth of spring’s sun, protected by a blanket of soil, the larva of the Japanese beetle stirs. The race is endless and ultimately unwinnable, and the costs in time and resources irreplaceable, but the gardener as manager of his surroundings is an optimist. Every gardener comes to spring trying to overcome the pervasive lack of time and the evasive nature of garden pests, the shock-troops of nature’s onslaught, an invasion of harmful, damaging species from outside the garden.
Thrown out of Paradise, equipped with a spade, rake and hoe the gardener prepares to return by recreating Eden using the knowledge of horticulture. The guide to success, the instruction book on how to establish relationships that produce a harvest of plenty, horticulture is the collection of processes and information gathered through the millennia to serve the present. Mostly science now, but still flavored with folk wisdom handed-down through the generations, horticulture tells the gardener and the landscape manager which species will live and which will be overwhelmed; how deep to plant the peony and when to plant the corn; how to save the oak and where to site the cactus. The Western traditions that enabled the science of horticulture not only lead to new varieties of hostas and new shades of color in daylilies but to hotter cayenne peppers and larger Halloween pumpkins. It is horticulture that informs us as to where our cacao trees will grow so that we may gratify our sweet-tooth cravings and when to pick the grapes for our dinner-wine celebration.
The reach of horticulture is expressed by the modern extent and present range of definitions. Horticulture is the practice of gardening which in itself is a vague notion of work associated with the cultivation of plants. But horticulture is also the science of caring for gardens and small scale agriculture as well as the industry of plant cultivation. So horticulture involves plant propagation, production, breeding and genetic engineering, botanical biochemistry and physiology. Horticulture provides information that enhances yields, quality, nutritional as well as ornamental value, and works to improve resistance to insects, diseases, and environmental stresses. Traditional horticulture is the compendium of knowledge about the way our interrelationships and interdependencies work with our efforts to shape the land to suit our human needs.
The present study of horticulture demonstrates the depth and spread of its historic roots. Botany, soil science and identification, indoor and outdoor plant identification, Integrated Pest Management (IPM), business management, propagation and production, floral and landscape design, landscape construction, container gardening, aquatic gardening, arboriculture, herbs and medicinal plants, turf management, fruits and vegetables, perennials, greenhouse production, safety and hazards, as well as basic chemistry, biology, and mathematics constitute the core of the working knowledge and skills needed by today’s horticulturist. The professional horticulturist as beneficiary of two thousand years of study will know, among other things, the principles and techniques of reproducing plant varieties by seed, leaf and root cuttings, bulbs, corms, tubers and rhizomes; layering, divisions, grafting, budding, and tissue culture as well as the fundamentals of seed structure and vegetative makeup of plants. In addition he or she will master structures and functions of plants, the associated effects of environmental factors on plant growth, and will have a working knowledge of the fruit, nut, vegetable, bedding and pot plant, cut flower, nursery and landscape industries. Students of horticulture will learn about horticultural crop families, growing systems and culture needs, soil preparation and fertilization, selecting and propagating varieties, preventing pests, regulating growth, harvesting, value-added processing and marketing. And least but not less, the professional horticulturist will be able to address causes of and solutions to air and water pollution, soil erosion, pest challenges and problems, loss of biodiversity, deforestation, energy depletion, potential changes in climate and invasive species.
While much is written from a Western viewpoint about the horticultural arts, the same needs and knowledge of plants are seen and studied in Eastern landscape traditions. Bonsai, the Japanese landscape art form, miniaturizes and freezes the ideals of perfection inherent in Zen. Nature is reflected in a frozen tableau by using the knowledge of how to form a shape by careful trimming of equally carefully chosen plants. Which plant to choose; when to prune the roots; what soil to use; when to cut the foliage are all integral to creating an image of nature in miniature. The need to control, to freeze time, is buried deeply with in the tradition and the art of bonsai and are an unspoken outcome at the heart of western gardening traditions, too.
Broadly speaking then, horticulture is an art – an art of knowing when to plant, where to plant, how to plant, and most importantly, what to plant. This is the basic knowledge of good and evil, beneficial or harmful, useful or superfluous, belonging or not-belonging (invasive). These positive, necessary fundamentals of procurring human needs from the land are supplemented by the quiet inverse of knowing what species belongs and which does not. Horticulture speaks to us about the intersection of beauty and danger. The plant family to which the potato belongs famously offers to mankind food, spice and drugs. Potatoes, peppers, and nicotine represent the wide-ranging contributions of this family of flowers. These nightshades, however, as they are called in common parlance are known by their scientific or botanical name as the Solanaceae. The Latin verb solari, to sooth, may explain the name to which cigarette smokers can attest. The list of food sources within the family is astounding. Sweet and chili peppers, tamarillo, tomatillo, eggplant, and tomato are a few of the beneficial plants found within in the nightshade family.
The desire to exert some kind of control over one’s destiny combined with the basic needs of life - food, fuel, fiber – translate into a primary pursuit of knowledge. The importance of knowing which plant kills and which cures is an obvious outcome for most of the world even if some of us think we are no longer impacted by the power of plants. Mathematics and physics combined to describe a solution for removing a boulder from a field. The pry bar and the fulcrum moved both the earth and the rock. The art of alchemy drove a pursuit of learning about the physical world that would by the 18th century be ‘transduced’ - an alchemical term of art - into the study of inorganic chemistry. Illness was addressed by the growth in medical knowledge that demanded a specific and detailed understanding of plants.
Enticing flowers like the aptly named Belladonna, the beautiful lady, beckoned like Greek Sirens leading the unwary to the shores of eternity. The beauty of the Sirens song waylaid mythological travelers as do the dangerous trumpet-shaped-flower beauties of the hallucinogenic members of the nightshade family. To fall asleep under the spell of the devil’s herb, Atropa belladonna, is to never awake in this world. One of the world’s most toxic plants; a few berries can kill a child. Also in the family are the witch’s weeds, the Daturas, whose common names offer up a history of less than positive experience: Hell's Bells, Devil's Weed, and Devil's Trumpet. Under the influence of these queenly shadows of the night, ingestion results in delirium and the inability to separate fact from fiction, reality from fantasy, and the possibility of death. With both the Greek Sirens and the garden shades of night, those who survive their assignation with destiny tell tales of a very unpleasant journies/. It is this combination of beauty and danger that horticultural knowledge explains to those who venture forth from the grounding of the known into the chaos of other.
Knowing for sure what to cook and what to eat, what to touch and what to watch, belongs to the domain of horticulture. The look-a-like invader is a primal problem for the gardener or the explorer. Claytonia perfoliata commonly known as miner's lettuce alluding to its use by miner’s in California’s mid-19th century Gold Rush used to prevent scurvy, is also known as winter purslane, spring beauty, or Indian lettuce. A salad mistakenly made from Atropa belladonna instead of the helpful Claytonia will have serious and potentially deadly consequences. Identification confusion does not have to lead to death, but can lead to intense discomfort affecting the quality of life as anyone who is allergic to poison ivy can relate. Which vine is the nasty personal space and garden invader: the native Toxicodendron radicans (poison ivy) or the non-native Hedera helix (English ivy)?
Distinguishing differences, assigning a name, establishing relationships, and adding a value statement is the work of horticulture. The very word horticulture is derived from two Latin words, hortus – the garden, and cultare – to till. The knowledge gleaned from the Tree in Paradise is understood to be the knowledge of tending or tilling a garden. The ill-gained knowledge of Eden was also the key to survival. Knowing for sure that the fig leaf would not cause physical discomfort was an important piece of information supplied by horticulture through, perhaps, at first, experience. Learning how to grow cotton to supplant the fig leaf enhanced human life and was made possible by the information provided by the knowledge that we would eventual collect into the science of horticulture.
We can imagine the origins of horticulture in the mists of time after Paradise was lost. The knowledge of good and bad, the original sin not-with-standing, comprises the core of the critical principles of horticulture. Knowing the name and function of a species is a primary activity of horticulture. Less mythologically and yet somewhere along mankind’s journey to the present, traveling bands of human decided to stay in one place long enough for members to notice plants growing where hunting experience would not have suggested, perhaps, for example, near the human clearing. The medicinal or pharmaceutical use of plants was from the earliest times intertwined with horticulture. Greek plant collectors and root diggers called rhizatomoi were botanical specialists, an early version of today’s pharmacists. The study of human connections to the land and with the species that provided sustenance was by necessity the first study in survival. Even hunter/gatherers need to understand the fragile interactions that exist between living things and the physical world upon which they live. Horticulture addresses therefore the matrix of systems that consitute the landscape up on which mankind depends. An awareness of how the forest edge relates to the woodland clearing is a key to finding a meal. Knowing the location of an edible plant, knowing for sure which part of the plant might be eaten and when it might be toxic comprise a direct necessary skill set. Rhubarb, for example, a plant whose leaves are toxic has stalks that are used to make pies and provide tart flavors in cooking. Our sweet confection would bring death without the practical information of horticulture. Horticulture tells mankind where and when and what to harvest. George Sarton (1884-1956), the "father" of the history of science, reinforced the long, important reach of basic plant skills when he wrote in Ancient Science Through The Golden Age Of Greece the "…farmer was aware of many mysteries surrounding and threatening him; he was every day at the mercy of the elements and of luck."
The ancient Greek philosophers led their students through complex intellectual concepts in gardens, and were very aware of the relationships between man and the plants therein. In the Academy and the Lyceum it is not too far-fetched to presume that horticulture was a topic of interest and investigation. Aristotle’s students discussed and studied definitions, forms, and growth of garden plants as well as their practical use. Tyrtamos “Theophrastos” of Eresos, born on Greek island of Lesbos located in the northeastern Aegean Sea, was a student of Aristotle and became the next director of the famous Lyceum in Athens. If there were saints of horticulture, botany and ecology, Theophrastos through his studies and works, De causis plantarum/The Causes of Plants and De historia plantarum/The History of Plants, would be among the first rank.
In the grove, surrounded, as it were, by a controlled landscape or garden, Socrates lectured to his students including Plato. For teaching uncomfortable ideas that challenged them current notions of the world, the teacher was tried and condemned to death. The plant species of choice that we know today as Conium maculatum, poison hemlock, was the preferred method of execution. Perhaps the drive of Theophrastos, who was a student of Aristotle who in turn was a student of Plato, to collect, understand and disseminate a knowledge of plants was in some small part due to the stories of the great philosopher’s death. How to end life, and how to save life, were in the hands of people who knew about the locations, relationships and functions of individual plants in the world.
By the time of Julius Caesar some 2100 years ago, people who needed to know (in Latin scientes – a knowing one) about plants were dividing their research and acquisition into two distinct but related disciplines. Natural philosophy would lead to the big sciences of meteorology, physics and chemistry and agriculture to name a few. Unlike agriculture however which tends to focus on large crop production systems, the wider discipline of horticulture is wonderfully described by Marcus Terentius Varro who lives in the early years of the 1st century BCE. Prolific writer, soldier, historian, natural philosopher and practical Roman farmer following in the geographic relating, descriptive footsteps of the historian Xenophon of Greece and Cato the Elder of Rome, Varro explored horticulture in De Re Rustica/On Agriculture offering readers information about the garden and landscape practices of grape cultivation, grafting, composting through animal waste, soil suitability, inoculations, fodder, and harvest storage.
The second area of study was the pursuit of medical and pharmaceutical remedies and cures. How to grow, where to find, and how to recognize are direct needs of the botanical druggist. While the first pursuit of knowledge kept families fed and therefore healthy, the second found cures for those things that ailed them. Pedanios Dioscorides, a military surgeon in the legions of Nero wrote De Materia Medica/Of Medical Matters in which he describes some 600 plant species including references to the roots, stems, leaves and some flowers. After the brilliance of Greece and the early bloom of Roman civilization, the written record of scientific horticulture goes dormant with the death of the great physician Galen much like oriental poppies after their spectacular spring flowering.
Horticulture after the 1st century focused on the herbal and medicinal uses of plants and would directly lead to the science of taxonomy. It would be over 1500 years before the research would combine the scientific method with exploration and see the explosion of horticultural discoveries. Investigating how to extract from a local ecosystem the best human use was the mission of horticulture. Driven mostly by folk knowledge and lore, curious minds sought after plants that could cure or correct ailments. A gatherer would rise to her task (or his) trying to identify good plants from bad. A good plant was one that not only addressed a health or medical issue but whose harm was less than the good it offered. A bad plant had no redeeming features and might additionally cause damage or death. The duality of the Serpent’s Gift was carried to the fields in the search of remedy. The effect of the plant was the goal of the day, however, cause would have to wait until the 17th century. These earlier practitioners of the gardener’s art worked in a world of dualities because they saw and sought the effects and not causes. Attempts to explain the effects bordered on the fantastic. The spots on the leave of the lungwort, Pulmonaria, resembled the markings of a diseased lung and accordingly were assigned the curative properties relating to lungs and the pulmonary system in the hope of providing medicinal relief
the Greek philosopher, Heraclitus of Ephesus’ famous quote that all is flux, nothing is stationary (Πάντα ῥεῖ καὶ οὐδὲν μένει) describes with ancient wisdom the gardener’s challenge. From seed to seedling to sapling to shade-tree, each step is seamless and constant. How to identify each stage of a plants growth, in essence how to recognize a potential cause lay at the heart for the great leap from lore gained from experience to knowledge accessed through science. Knowing for sure what plant you are harvesting is the bases of the discipline of horticulture. How many people died before the herbal qualities of goutweed, Ammi visnaga L. Lam, and the death causing properties of hemlock, Conium maculatum L., were firmly understood. Goutweed, for eample, is a spice with pharmaceutical properties and is related to poison hemlock that was used to execute Socrates. The two plants themselves are related to a whole family of species, Apiaceae or Umbelliferae, which provide food, drugs or death when misused or identified. The familiar edible members, however, include carrots, parsley, parsnips, cilantro, and dill. The divide between herbal and spice is pleasantly fuzzy as are the definitions of many things when one looks too closely. The litany of spices blends to medicinal cures of yore: anise, caraway, chervil, coriander, and cumin in a tangy pharmaceutical change ringing.
And, while in hindsight seemingly self-evident, the relationship of the parts and stages of a plants life is by no means clear to those not steeped in the wisdom and experience that gives knowledge to the gardener. In the first part of the 16th century Andrea Cesalpino, physician to the Medici and to Pope Clemens III, would inspire future students of botany with his philosophical approach to a classification system that would find patterns in the structures of the plants. While he rather famously, and incorrectly it turns out, ascribed the origin of flowers from the leaves of the plants, he on the other hand astutely and correctly described the need and appearance of a system of classification that would ultimately lead to the study of taxonomy. Cesalpino wrote that " [u]nless plants are reduced to orders, and distributed into their classes like the squadrons of an army, everything is bound to fluctuate.
In this explosion of learning in the spring of scientific inquiry, Cealpino was not alone. He was joined by a long list of early botanical intellectual explorers. Valerius Cordus, a German physician who in 1540 described a technique for synthesizing ether, improved the descriptive accuracy of plants including species from exotic locations. Charles De L'Ecluse, a Flemish medical doctor who never actually practiced medicine, created one of the first botanical gardens in Leyden, introduced the potato to Germany, and fired up the bulb culture that would in part financially empower the Netherlands to imperial world dominance. The great herbalist and one of the founding fathers of botany, Leonhardt Fuchs, was a doctor of medicine and personal physician to the Margrave of Brandenburg. At the invitation of the Duke of Württemberg in 1533, he helped reform the University of Tübingen directing it towards a humanistic course of study. He created the first medicinal garden in 1535. Such was the stature of his learning and his knowledge of the function of plants, horticulture that he served as chancellor of the university seven times. Known also by his Latinized name, Fuchsius Leonhardus, later memorialized by a favorite ornamental flower, the fuschia, he created one of the first pictorially accurate botanical book as well as encouraging the use of newly discovered pumpkin and corn in Europe.
Taking advantage of the latest in the ‘hi tech’ of the time, the printing press, John Gerard, Gervase Markham and Thomas Hyll were among the first to commend in print plans of gardens of food and pleasure for considered study. Leonard Mascall wrote of planting techniques and grafting indicating “…the divers proper new plots for the Garden. Also sundry expert directions to know the time and season when to sow and replant all manner of seed.” Mascall also makes a point to identify “…remedies to destroy snails, canker-wormes, moths, garden flees, earth-wormes, moles, and other vermin.” Mascall prescribes solutions for garden problems, which are familiar to us today, telling his readers that “[t]o destroy pismiers or ants about a tree…Ye shall take of the saw-dust of Oke-wood oney, and straw that al about the tree root, and the next raine that doth come, all the Pismiers or Ants shall die there. For Earewigges, shooes stopt with hay, and hanged on the tree one night, they come all in.”
This explosion of botanical interest was in every sense the study of horticulture. This intellectual interest and inquiry laid the foundation for our present dynamic landscape template. Mankind, for so long asymmetrically arrayed against the infinite majesty and potential destructive forces of untamed nature was creating a tool to overcome the odds of survival. The study of species, the art of classification, the research that enable subjective valuations of the components of nature for the enhancement of mankind were driving forces of at the beginning of the modern age. Nature, the wild, unexplored and unnamed Other, was being corralled and domesticated by humanity that yet felt over-matched and at the mercy of forces beyond its control. The rhythm of naming parts and parcels of the landscape became the dance of control.
The recognition of change would drive the conversation of scientific enquiry from the 16th century right through the 19th century. Horticulture examined the continuous nature of change in the landscape describing analytically in detail each step of growth and decay. It could do so by first assigning a name to which an effect or function could be attached. A system of naming or classification was a gift of the Tree of Knowledge; the primal urge to know good from evil, benefit from harm in a dangerous and uncertain universe.
It is hard today to imagine the enormity of the world as once felt by mankind. I can remember reading books of exploration and discovery with maps that included regions labeled exotically “terra incognita”. Scientific missions that were lost in far away jungles and barren landscapes filled with the terror of the unknown. The fragility of control was reinforced and obvious, for a garden untended quickly reverted to a “natural” state. The duty and mission of man was to tame this unruly dynamic system that festered beyond the garden fence. To adequately control the massive forces of nature, horticulture provides the first line of defense. A landscape with a name is no longer unknown. A landscape can be identified by the plant species it supports. Everything, therefore, is dependent upon the name.
In the 17th century the art of naming was not yet a science, and horticulture was not yet a discipline. The scientific method was becoming the new tool of knowledge and learning. The gardener first asked a question. Then he or she studied and researched what was known about the question. A hypothesis was constructed that was tested through experimentation. The information in the form of data was analyzed and a conclusion drawn that was then communicated to a wider audience to become part of the body of scientific knowledge.
In an age when many clergymen were also scientists, the Reverend Stephen Hales was an English example of a physiologist, chemist, and vicar. In his Statical Essays, volume one, Vegetable Staticks (1727), are accounts of experiments in plant physiology that include the loss of water in plants by evaporation, the rate of growth of shoots and leaves, and variations in root force at different times of the day. The role of natural philosopher was rising to an apex below which the modern disciplines of horticulture, agriculture, biology, botany, taxonomy, chemistry, physics, medicine and mathematics were differentiating into areas of specialized knowledge. At the height of its reach the complications of horticulture were forcing a simultaneous break up of the discipline into unique categories of research and understanding. The impetus of this specialization was the search for a cause of an effect rather than for just the effect itself.
In the 1600s, the study and application of horticulture begins to be presented in terms of hard science such as botany and biology as well as related fields of chemistry and physics, versus applied science such as garden and orchard cultivation and design (horticulture in a modern sense) as well as the field of agriculture. Though not yet well formed the idea of pure research and applied science was coming into being. Jethro Tull, not the 20th century recording artist, but rather the inventor of the horse-hoe and seed-drill showed the practical side of a farmer even as he showed signs in his work of the nascent state of scientific knowledge. He asked what plants ate and answered earth, which then supported the need to for cultivation, the continuous disturbance of the land, on order to feed the crops. Leaves, he claimed, were the lungs of plants, an observation that was close for the wrong reasons.
Technology and luminaries came together in the late 17th century to research plants, to draw forth every possible benefit that nature might give. Rudolf Jakob Camerer, also known by the Latinized surname Camerarius, John Ray, and Nehemiah Grew researched plant reproduction while the nurserymen, Thomas Fairchild and John Bertram, experimented with practical hybridization. With the help of Antonj Van Leeuwenhoek’s newly introduced technological tool, the microscope, the great Robert Hooke, famous today for his law of elasticity (Hooke's law) and his book, Micrographia, investigated the cellular composition of plants first applying the word "cell" to describe the basic unit of life. The great strides of science enabled greater knowledge about plants that could provide a better life for humanity. The efforts can be summed up as how to get more from the garden and the land by finding out how plants work and by introducing new plants to the landscape.
Richard Bradley, the first Professor of Botany at Cambridge University, writes in the Preface to his 1718 book, New Improvements of Planting and Gardening both Philosophical and Practical, that “..there is no Subject of more general Use and Advantage than the Cultivation of Land, and the Improvement of the Vegetable World.” This idea of improvement is key function of horticulture, the cultivation (cultum) of the garden (horti), which seeks to address any physiological or biological cause that might hinder the positive effect or use of a landscape and the access to its resources. Bradley goes on to say that well meaning writers in the past had given advice “… by heaping together a Load of Observations from Varro and Pliny, without carefully considering wherein their Experiments differ from the Genius of our Soils and Climates.” Scientific method was to be harnessed to revolutionize control of the land.
Bradley, who brought ideas about horticulture back to England after a trip to the Netherlands, lays out a novel idea in an attempt “… to prove that the Sap of Plants and Trees circulate much after the same manner as the Fluids do in animal Bodies; which may be one Argument to shew (sic) the beautiful Simplicity of Nature in all her Works.” His next section deals with the Generations of Plants and the “…Manner how their Seeds are impregnated… [which ]… will be a great Use to all Planters, by directing them in the proper Choice of their Seeds.” He follows this with chapter on the Differences of Soils in which he will demonstrate which soils are “…natural to each Tree, and how all Kinds of Soils may be mended, alter’d, or improv’d, by proper Mixtures with each other…”. A Method of Dressing the Woods for timber wherein he proposes “…a new, easy, and practical Way of raising Woods with very little Expense…” After a chapter on profitability, Bradley then takes up the Flower-garden and “…prescribe[s] the properest (sic) Methods for rendering that Part ornamental.” He continues, “I have there given the best Method of Propagating and Introducing all the Ornaments of the Garden, as Ever-greens, Flowering-shrubs, Perennial and Annual Flowers, and Bulbous-roots Plants, with their differing Heights, Beauties and Times of Flowering.” He brings the work to a close with the tools and information necessary to propagate fruit trees and “...tender exotic Plants.” Remarkably prescient in light of modern landscapes and invasive species, Bradley writes in his chapter three: “I suppose that no one is ignorant that the greatest Part of these Flowering-trees and Shrubs, which are at this time so well known to our Gardeners, are Exotics, (Italics are Bradley’s); and it is well worth our Enquiry what Climes they were first brought from…”.
The various functions of the parts of the plant and the functions of the plant within the landscape were described in detail by chief gardener at the Chelsea Physic Garden, Phillip Miller, in his ambitious re-issue in 1735 of The Gardener's Dictionary containing the Methods of Cultivating and Improving the Kitchen, Fruit and Flower Gardens. He compiled a concise reference in which he his cautious to use proper nomenclature for identification of a species function and care with in the landscape. The entry for lavender provides an example of the level of detail as Miller writes: “Lavendula, lavender. It is one of the verticillate Plants, whose Flowers consist of one leaf, which is divided into two lips; the upper-lip standing upright, is roundish, and for the most part bifid; but the Under-lid is cut into three Segments, which are almost equal: These Flowers are dispos’d in Whorles, and are collected into a slender Spike upon the Tops of the Stalks.” (Vol. 2)
Miller next identifies several species or types of lavender and then describes them in terms at times familiar to today’s gardeners and ecologists noting that lavender latifolia “…tho’ very common for most Parts in Europe, yet in England is rarely to be found…” while lavender latifolia, sterilis “…is a Degeneracy from angustifolia…”. Miller’s use of the word degeneracy is a critical piece of the work of the gardener in the managed landscape, for it is in part the landscaper’s mission to enable high culture through cultivation, and in doing so avoid the degeneracy inherent in the wilderness just beyond the garden gate.
Bradley, Miller and other natural philosophers, proto-scientists and nurserymen were beginning to create the great calculus of the garden, horticulture, by mapping cause to effect. They were identifying points of infinitesimal change at which a measurement could be taken or a decision made to create a desired outcome. They used the latest inventions and hi-tech tools like the microscope to aid their quest for information, for models and for theories of the relationships in the landscapes and therefore their world. The cross-inter-disciplinary nature of study in the 1600s, the fluid nature of research and investigation allowed for creativity in exploration if ideas. A partial list of the works of John Abercrombie, show the wide ranging professional interests that were covered by the science of horticulture: Every Man His Own Gardener (1767), The Universal Gardener and Botanist (1770), The Garden Mushroom, Its Nature and Cultivation (1779), The British Fruit Garden and Art of Pruning (1779), The Complete Forcing Gardener, etc. (1781), The Propagation and Botanical Arrangement of Plants and Trees, Useful and Ornamental (1785), The Complete Kitchen Gardener and Hot-Bed Forcer (1789), The Hot-House Gardener (1789), and The Gardener's Pocket Journal and Annual Register (1791) 
This was the age of Newton and Leibnitz, and the calculus in mathematics; and the rapid expansion of the scientific method for understanding the whole world, not just the space right outside the imagination. It was also the age of the last of trials for heresy and the Thirty Years War in which men such as Kepler had to be secretive as to some of his notions about the cosmos for fear of indictment by the political establishment. Hiding in the darkness just outside the garden fence still scurried gremlins and uncontrollable spirits who could without warning intrude upon the serenity of the garden bring death and destruction. The poetic images of Spencer’s Fairie Queen rang true and strongly influenced the world-view of European man who knew for sure that there were living not too far away cursed beings “…in wasteful Wildernesse...by which no living Wight passe, but through great Distresse.” (The Faerie Queene, Book 1 edited by Martha Hale Shackford) The degeneration of the landscape beyond the sanctuary of the garden psychologically bolstered imaginary fears that became incorporeal evils.
A differentiation is made between what is manageable and measurable versus what is infinite and un-usable. The differentiation of the stem from the root provides insight to the function of the plant itself. A differentiation of use to mankind produces a function that assigns a value of good or not-good. What is the purpose of the leaf, the horticulturist asks, how does the flower function, why are there roots, what is the inter-relationship between the seed in its pod to the flower and to the seedling in the soil; these questions now taken as common knowledge are brought together in the great work of circumscribing the processes of gardening and the garden. The role of a plant in the garden and the relationship of its parts to the greater community of the landscape were detailed in no small part by connecting a plant’s change in physiology through time to its growth to the motion of the sun and seasons. For the gardener it is paramount to know when to plant which plant as well as when to prune and when to divide or and when to harvest. It was equally important to understand which plants can grow together in full sun and which plants tolerate shade. A plant with no discernable use to mankind at any point in its life is by human definition without value. And this human definition is all that we humans have to work with.
The inverse of this process horticultural differentiation is the integration of what is known through experimentation and is bounded by the limit of of a garden’s perimeter, edge or, if you will, the garden wall. To use the calculus of horticulture, the gardener needs to differentiate types of plants, scientifically and commonly referred to as species made possible by the great system of taxonomy created by Linnaeus. To manage and to measure what is possible in the garden is done by horticultural integration of a landscape.
Carolus Linnaeus, known also in recognition of his contributions to learning by his ennoblement as Carl von Linné, or more simply just Linnaeus, created the naming system for living things including plants in and out of the garden. The Linnaean system uses a nested hierarchy of categories, starting with three Kingdoms divided into Classes that are then divided into Orders, in turn sub-divided into Genera (singular: genus). At the end of the nesting process are found the division into Species (singular: species), itself divisible into ranks of plant species now called "varieties". The importance of this system is so fundamental (and mostly now taken for granted if even thought about by society) as to have become a kind of modern accepted intuitive knowledge presumed to have always existed. Who today can imagine world in which there is no common underpinning to the classification of living things. The differentiation of species was based upon shared physical characteristics. The resultant naming is allows for an attachment of values and the assumption of function. Now a species could be named and assign a function which in turn could be tagged with a value of either beneficial or harmful.
Systema Naturae, first printed in the Netherlands in 1735, contained by its 10th printing in 1758 classified over 4,000 species of animals and 7,500 species of plants. Based upon a binomial naming convention first proposed by Gaspard Bauhin and Johann Bauhin in the 16th century the great work set out the principles necessary for an orderly naming system. Genera plantarum: eorumque characteres naturales secundum numerum, figuram, situm, et proportionem omnium fructificationis partium (1737) delineated plant genera. In 1753, Linnaeus published Species Plantarum, exhibentes plantas rite cognitas, ad genera relatas, cum differentiis specificis, nominibus trivialibus, synonymis selectis, locis natalibus, secundum systema sexuale digestas began to out in detail a nested hierarchy for plants that culminated in Systema Plantarum published in 1779.
The introduction to Genera plantarum outlines the needs for the function of orderly naming right at the beginning: “All that truly can be known by us depends on a clear method by which we distinguish the similar from the dissimilar. The more natural the distinctions this method comprises, the more clearly the idea of things emerge to us. The more objects our understanding engages with, the more difficult it becomes to work out a method—and the more necessary. Nowhere has the Great Creator placed so many objects before the human senses as in the vegetable kingdom, which covers this whole globe that we inhabit. Thus, if a pure method is of use anywhere, it is here, if we shall hope to gain a clear idea of Vegetables. “
From Linnaeus comes the injunction to join the similar with the similar, and to separate the dissimilar from the dissimilar. The great Western intellectual effort from the time of Aristotle until the middle of the 18th century rose like a wave towards the shores of a system of plant species classification. The great fundamental theorem of horticulture is the ability to differentiate species; to assess a particular related set of features through time at one particular instance and claim a categorical relationship. The motivational dream is a function consisting of a set of rules that provide a definition that identifies a particular species. The community of life around us, the biology that comprises a particular ecological system, may be expressed in terms of relational categories that are called species; we can reduce the complex to a single individual and identify its membership within a specific, biological set.
And now the horticulturist and the gardener could systematically express the benefit and desirability of a particular species. The naming convention as a consequence of Western civilization’s binary Aristotelian logic, allowed for the categorization by orderly systematic classification of species into a set of harmful undesirable and pervasive “wild” species with no visible value to the garden. This category of other was not hard to sell. The primary importance of the plant world was first and foremost in the minds of everyone, unlike today, when some of us are several generations removed from the vagaries of the soil and weather, mankind through the centuries fully felt the fury and the uncertainty of nature pounding on the garden wall every minute of every day. This is a world fast disappearing in which most people lived off the land affected directly by their knowledge of the relationships of plants, insects, diseases and animals around their home. Any failure to correctly identify was life threatening.
Horticulture’s function is to identify the particulars of the relationships and interconnections of living things to the physical world. Armed with a name events and experiences can be tracked through time. The seedling of a garden invader is detected at an early stage and the ultimate harvest increased by a rapid response called weeding. To plant necessarily implies a positive labor while to weed involves a necessary evil. The plant is good; the weed is bad, and an eternal struggle is firmly established in practice and in memory.
Through constant attention and continuous selection, the gardener chooses which species will be permitted to flourish inside the wall. Eden is recreated one plant at a time and through endless work and the knowledge of horticulture additional species are introduced each with its won identifiable function within the garden complex. Unsolicited additions or arrivals of any species from outside are prevented. The ultimate goal is control of the world immediately around us by careful, learned selection and the tool used is the accumulated knowledge of horticulture. The natural world is in a perceived state of degeneracy, of vagueness and of uncertainty that may be tapped or exploited to enhance the productivity of the garden through the applied science of horticulture. The day-dreams of a time gone by are colored by the works of great men who found new uses and new skills to manage the land. There is for many a “Romantic” view of the past in which nature is a harmless-other to which one only needs to apply intellect and determination to compel the secrets of a good profitable harvest. Through careful cultivation a landscape generates culture. Through cultivation a group of people can begin to feed themselves predictably, and have the time to create works of art and memories of glory. With time’s gift of the science of horticulture comes education and knowledge which can touch the stars.
The very same landscape if not tended continuously will revert to a wild undifferentiated state. The wilderness for settled humans who have moved from hunting and gathering to a more sedentary life style is undifferentiated for there is not enough direct, tangible yields for the larger number of individual; there is only haphazard chance encounters with useable resources. From inside a managed landscape the outside is a blur of unregulated potential uses, but without clarity or definition. Horticulture teaches mankind how to select and transfer productive species from the wild into a controlled state of cultivation and in doing so to raise the level of culture through the increased harvest which then can support greater numbers of people.
Horticulture also addresses the problem of a landscape once disturbed that does not revert to an idyllic pastoral scene but rather almost immediately becomes an open wound festering with competing species each trying to take advantage of the absence of the complicated webs of biological and physical interdependencies. Natural areas that are chronically disturbed through human actions do not revert to a pristine state but over time evolve into a new state of being.
I cannot imagine nature as an untamable adversary. The cosmic legion of horticulturists who named, essayed and found solutions to gardening challenges is brightly lit by the work of the inquisitive garden investigators of the 17th century. I cannot imagine a world in which I do not know the function of a flower or why too much nitrogen invites the aphid to attack. I cannot envision a world where every living thing is unknown and potentially an adversary.
 Edition: 28 - 1993 by George Sarton
 Nisi in ordines redigantur, & velut in castrorum acies distribuantur in suas classes, omnia fluctuari necesse est
 Censura literaria : containing titles, abstracts, and opinions of old English books : with original disquisitions, articles of biography, and other literary antiquities (1805)
 A Book of the Arte of and Manner howe to plant and graffe all sortes of trees, howe to set stones, and sowe Pepines to make wylde trees to graffe on (1572)
 Dr. Tim Rhodus. 2002. Department of Horticulture and Crop Science. Ohio State Universityhttp://www.hcs.ohio-state.edu/hort/history/076.html ://www.hcs.ohio-state.edu/hort/history/076.html of Horticulture and Crop Science
 Staffan Mueller-Wille and Karen Reeds. 2007. A translation of Carl Linnaeus’s introduction to Genera plantarum (1737). Stud. Hist. Phil. Biol. & Biomed. Sci. 38 (2007) 563–572
“Omnia, quae a nobis vere dignosci, possunt dependent a claroa Methodo, qua distinguimus fimilia a dissimilibus. Haec Methodus, quo magis naturalis comprehendit destinctiones, eo clarior rerum nobisnascitur idaea. Quo circa plura versatur noster conceptus objecta, eo difficuliu selaboratur methodus, at magtis necessaria evadit. Nullibi tot objecta humanis sensibus objecit Summus Conditor, ac in Regio Vegetabili, quod totu, istum, quem inhabitamus, globum tegit, replete. Ergo si nullibi pura methodus a re est; sane hic; si Vegetabilium claram idaeam obtinere sperabimus…”