What is a Species?

Specious (?) Speculations on Species 


Iris x pacifica ‘Tanus’.  This is a hybrid Iris of species know collectively as series ‘californicae’, a group of Iris endemic to the Pacific coast of the US, primarily California, some very localized, with several occurring north through Oregon, and one, I. tenax, all of the way to the Puget Sound area of Washington.  These species obviously can be crossed.  Their form shows the distinctive tri-partite structure of a classic Monocot, in Genus Iris taking this particular form with 3 ‘falls’, 3 stamen and stigma structures angling out from the ovary at center, across the brightly colored ‘signal’ on each fall and the 3 more upright ‘standards’.

I do not recall from high school biology how an individual species was defined to us in our text or class, nor do I in my college Zoology 200 series.  All that I have is a general understanding that it is a select population with a shared, narrow, range of physical characteristics, in the case of plants, best determined by their floral or reproductive parts, that is able to reproduce stable offspring with the same range of characteristics.  Webster’s defines species as:

“a category of biological classification ranking immediately below the genus or subgenus, comprising related organisms or populations potentially capable of interbreeding, and being designated by a binomial that consists of the name of a genus followed by a Latin or latinized uncapitalized noun or adjective agreeing grammatically with the genus name”

…Basically, a species is what has been determined to be a species, and assigned a ‘binomial’, by recognized experts, within what can appear to be, an ‘opaque’, classification system…a species is a species because ‘experts’ say it is.  Such a definition isn’t very helpful to a person who doesn’t understand the system under which an organism is being classified.  Because organisms do not ‘come’ with their own ‘labels’ (though they do contain their DNA which a handy field DNA ‘reader’, when someone comes up with such a thing, could ascertain and then with the appropriate algorithm, could tell us which species we are looking at) we are dependent upon others to ‘label’ them for us and if we lose a particular label, we are left to opinion and keys to help us sort them out, ‘keys’ that can seem unwieldy and leave us scratching our heads as we struggle over their meaning and at what can seem like insignificant and minute details.  (This is especially troublesome with particular genera, like Salix, the Willows, which remain poorly defined and even contentious.)  Other species, may be more distinctive and so, be more readily keyed out.  Often there are seemingly so many minute distinctions, requiring a hand lens and very specific knowledge, to know what we are looking at and whether it matters.  There are hundred’s of thousands of plant species and a constantly increasing number of hybrids and cultivars to add to the confusion.  Many times I consider myself fortunate when I can determine which genus or even family a particular plant might belong to.

Much of Botany has been a long process of description, of understanding ‘what’ we are looking at and describing it in such a way that others can also ‘identify’ it.  Science, looks at the details, the differences, to understand the ‘whole’.  Through the science of ‘Systematic Botany’ they attempt to make links between species, drawing historical lines of development from one to the next creating a story of life that is phylogenetically true, in an attempt to understand the development of life on this planet.  It breaks it down into its constituent parts and processes, looks for commonalities, checking the geological record and the patterns of shared chromosomes.  What then are the criteria by which we call one plant a species and another plant a different species…what is a ‘species’?  What constitutes ‘normal’ variation within a species?

Species and Sexual Reproduction

Species cannot be defined alone by their ability to sexually reproduce, only within that species.  Many species can hybridize with others.  This happens in nature where populations of different species, generally of the same genus, have overlapping bloom periods, in which one or the other is actively releasing pollen while the other’s stigma are ‘ready’ to receive it and a hybrid generation occurs.  Sometimes those differences which are recessive or ‘dormant’ in the two species populations, can manifest.  Of course species of the same genus may not flower at the same time or their hybrid progeny can be sterile.  In either of these cases, it is a dead end and propinquity will never produce a hybrid line.  Hybridizers have long taken advantage of this to produce unique plants for market and agriculture by storing pollen and selecting those plants with the characteristics they want to emphasize or ‘add’.

Every species has within it a range of possible forms or expressions.  Humans have taken advantage of this through our use of the process of selection in agriculture though we continue it more broadly today as we grow seed lots and select individuals for use in our own gardens.  When this is done over a period of many generations, thousands of years, the appearance of progeny can be both very different than the original wild species and remarkably consistent.  For example, the species Brassica olearacea, a wild mustard, has been transformed into the many varieties of today’s Cabbages, Cauliflowers, Broccolis, Kales and Collards.

When pollination is successful between such species in ‘nature’, ’Hybrid swarms’ can arise when they produce successive generations, backcrossing with the parent plants, producing individuals with intermediate characteristics.  Pollination and successive generations could spread back through the general population after many generations effecting change, but I’m not sure how often this happens. So, are species species only because of their historical isolation?  If pollinators can’t bridge the gap?

Most plant species have been here for many millions of years, co-existing with each other or isolated. Presumably, when isolated like many individual Rhododendron species that might only occur in a single narrow valley in China’s southern mountains (China alone is home to 500 different Rhododendron species), they evolve and stabilize, their particular mix of  genes interacting with a fairly stable set of conditions over many generations.  But, what about the many cases like that of Arctostaphylos patula, a Manzanita species native to the eastern Cascades, south and east into the Sierras and Utah, whose range overlaps with Arctostaphylos columbiana up on Mt. Hoods eastern flank?  Here can be found natural hybrids.  Their propinquity is not a recent occurrence.  These two separate species have likely been there for thousands of generations, at least.  Yet, here still are the two different species and their hybrid progeny.  This is not an unusual situation in native landscapes around the world.A Field Guide to Manzanita.jpg

Picture two masses, moving, slowly, through reproduction, their seed carried variously to the wider landscape, individuals fixed to place, the ‘pressure’ moving it related to the suitability of the conditions along the growing ‘edge’ of the population.  A. columbiana, growing from its more western and wetter spreading center, is constantly seeking to expand its territory casting its seed out via the bellies of birds along its eastern edge.  The seed germinates or not.  Those that do, either grow on or, finding conditions inadequate, or the competition to fierce, succumb, and the ‘line’ that defines the populations perimeter, holds fast.  In this manner the species move across the landscape, every Spring renewing their efforts.  Because of the stability of conditions around them these ranges are relatively constant.  Significant ‘movement’ can take take thousands of years, unless something catastrophic, e.g., a massive landslide or fire, happen…or of course a human induced one.  Life cannot go where it is not supported.  When it attempts to do so, due to conditions that are uncharacteristic, and later, the moderated pattern returns to ‘normal’, the line ‘retreats’.  It is a dynamic process, ebbing and flowing, where it can.

Species of the same genus tend to occupy different niches.  Each species can have quite different site requirements, or they may be only marginally different, requirements that ‘favor’ one landscape, one place, over another.  Plants will form into recognizable communities, each playing a role, occupying various niches, each ‘member’ species belonging ‘with’ others of a wide range of genera.  Conditions change across a landscape, grading from one definable plant community into the next, forming a more mixed population along these edges where they come together, in what is called ecotones.  These edges are not always sharply defined, nor are they necessarily continuous.  Other communities can exist as ‘satellites’ blurring the edge further.  Species members of ecotones are more likely to come together in these areas where pollinators can ‘bridge’ the gap and successfully cross them.

Picture a second species, whose requirements would locate it in slightly colder, drier conditions, like A. patula, a forest edge member of the higher elevation plant community that often colonizes burns and open ground.  These are growing with their own established and different relationships within a preferred plant community.  Arctostaphylos patula is ‘moving’ up Mt. Hood’s eastern flank while Arctostaphylos columbiana, is moving easterly from the wetter conditions that define the more westerly landscapes.  Each is at its limit or has maybe established smaller populations beyond the main body, isolated from the rest by changed conditions.  It is along edges in general where landscapes are most dynamic and exhibit the most diversity.  So, why don’t these hybrids with their mixed genetics take over and replace the two species?  Aren’t they uniquely adapted?  The answer might be, that yes, they are uniquely adapted to these precise conditions, but that does not equate to being superior to the two parent species on their ‘home’ ground.  Their hybrid progeny may persist for many years, even if they themselves are sterile, shrinking and growing in size with the changing conditions and the movements of the two parent species/masses.  Again, the situation is dynamic, but our perspective and lives, as humans, are too short to register it.  We see these landscapes and with our ‘still picture’ memories see these dynamic moments as fixed in time.

Living organisms, plant, animal and microbial, are a response in time to place and the long line of genetics that defines them.  Each organism, each individual, is a tiny piece that we may know and examine in a moment in time.  We believe that we see life as it is.  While it is in fact in a continuous state of change.  No two individuals are ever exactly alike.  Living organisms and the cells that comprise them are continuously being replaced, cells divide and grow, in a way that leaves the individual recognizable.  Life is reproduced in unique form, evolving toward….Building complexity and diversity into the larger whole over many millions of generations.  I ask again, ‘what is a species?’

Defining Species by Physical Description

Carl Linnaeus devised the classification system we still use today in our study of living organisms.  It is a pyramid built on a base of 100’s of thousands of species each described and defined in detail, each one a basic unit upon which the ‘whole’ is built.  This constitutes this species…this another.  Species are then compared and those that share common traits are grouped together in the same genera.  This second tier forms the ‘genus’ level ‘supported’ by its constituent species, sometimes hundreds, while others may have as few as a single species.  The third tier is that of plant Families each including closely ‘related’ genera, that share broader more generalized traits.  Families can include many thousands of species.  Often times families can be divided into sub-families, each containing species with a more specifically expressed trait that varies between the different sub-families.  This system groups species together in increasingly broad, general, classifications, as you ascend the pyramid, ultimately defining the entirety of the plant Kingdom.  Each class, related directly to the more general one ‘above’, each successive division, separating, defining it, in its details, ever more uniquely than those species that ‘diverged’ having followed other genetic life paths.  Each of these ‘paths’ form a ‘phylogenetic’ branch on the larger ‘tree’.  Some of these become ‘dead ends’, the process of speciation, of further development having come to an end, waiting, ultimately for either its extinction or the impetus to restart the process.  The Invention of Nature.jpg

Previously, for centuries, our attempts to make sense of the life we examined butted up against competing ideas of how to define it.  Our present system is posited upon the premise that all life is reproducible in stable patterns and that its different ‘expressions’ are related to one another, that each organism shares with others particular characteristics, that can be traced in ever finer detail as one moves ‘out’ from the over arching designation of Plant Kingdom, through its several levels down through Orders, Families, Genus and finally, Species, a set of criteria that depends largely on floral or reproductive features in their details, but more general and ‘primitive’ characteristics, as well which are widely shared by all or most plants in its broader catagories.  Prior to Linnaeus many attempts to define and describe life were built on the belief that God created all life at one time, independent of one another and fixed forever in time.  Botanists, or natural philosophers, were merely trying to devise a method to catalog God’s creation…there was much disagreement.  Under our current system, a species is the ‘finest’ designation of a population, that is ‘complete’ on its own and capable of perpetuating itself stably into the future.  There are sometimes ‘finer’ hairs that are split when botanists recognize subspecies and ‘populations’ of a species that possess unique characteristics from having developed isolated from the larger population.  It never ends.  Still what is a species?


This is a bud of a hybrid resulting from a cross of Iris douglasiana and the hybrid I. x pacifica ‘Big Money’, that occurred in a Park landscape.  It shows the two spathes that are defining in the entire Iris family, in an almost claw like structure.  From this emerges the bud with its typically elongated perianth tube.  Some Iris will have two flowers emerge from each ‘rhipidia’, e.g., the Siberians.  The details of these structures are all important to determining a species morphologically, by observing their physical structures.  Their isobilateral leaves, identical on each side, without top or bottom, though not necessarily so in their interiors, are characteristic of all Monocots. Iris ser. californicae may have stomata, pores, on the underside of drooping surfaces.

Botanists can describe plants in exhaustive detail.  This is in fact necessary before they can begin to understand just what they are looking at and how a plant may compare with others, how it may vary and whether any differences are significant enough to call it another species.  When differences are significant, when traits serve as consistent signifiers, ways to link individuals in one group or another, botanists will make note of them.  Collectors will make scrupulous field notes, noting precise locations and the conditions their samples were growing under.  They’ll collect leaves, flowers, fruit and seed, drying and pressing samples for later study, tentatively assign them a name and a collection number to keep track of it all, collecting cuttings or even live plants.  These will be examined over  time, often by many others looking in increasing detail, looking at sections under magnification, the layers of a seed coat, the details of pollen grains, the attachment points of a stamen’s filament and on. They will use terms like plesiomorphic to describe traits shared with ancestors, calling some ‘basal’ because these particular traits are defining and are shared within a genus or family and so characterize it.  They’ll write of ‘synapomorphy’ referring to ancestral traits that are unique and only occur in its evolutionary descendants.  They’ll place less emphasis on those characteristics that are of little phylogenetic help, traits that are only differences that are not helpful in linking one plant to another or separating one group from another.  Some differences are only differences. They may be ‘apomorphic’ or derived, having come about within that species without any antecedents or predecessor.  The examination goes well beyond what we can see when we casually observe a plant in the field or garden.  Taxonomy is the work of describing and naming species while systematics is more focused on their evolution over time, phylogenetics and the actual structure of the whole.  The concept of ‘species’ is central to both.

These ‘species’ are out there growing everywhere ‘unaware’ that they are species, unaware of the human hubbub that occurs in various societies, universities and gardening groups.  A species designation is ours.  It effects how we perceive and act in the world.  It is a classification system set by rules and conventions, by our practice of review, our need to group and understand.  A change of this system can redefine a species, genus or family, while any given organism goes about its ‘business’ of living, blithely ignorant of our change of the idea that some individuals may no longer be included with them, while others have been joined to them.

Species, the organism, whether a Dandelion or a Calypso Orchid, a Rufous Hummingbird or a Human Being, are composed of incrementally different individuals.  When grouped together, regardless of how we may classify them, the individuals will exist across a range, exhibiting various traits to a greater or lesser degree.  In statistics this plays out in the classic ‘bell curve’.  Organisms may sometimes exist as identical clones, but the way of nature is diversity through sexual reproduction, a mixing of genetic information.  Species designation defines a specific population in a way both narrow enough to be helpful and general enough to not completely overwhelm us.  The genetic reality of life will always be such that organisms may be more or less different than the species type botanists continue to spend so much time defining.  In a sense a ‘species’ is the ‘sweet spot’ that best serves to define a group of individual organisms. Yes, they are closely related.  Yes, when cross pollinated the progeny will exhibit traits very much like their ‘parents’.  Through our classification system we are able to paint an ever more accurate ‘picture’ of life and the evolving, dynamic process that still drives it.  It allows us to trace this development back through prehistory.  But something is still lacking in this definition of a species…because a species is an abstraction that we try to fit the world into…though in terms of description, it can be very close.  Still, what is it?  Lupinus latifolia, a west coast species of Lupine, in a very real sense, represents a particular strategy, a biological pathway, ‘favored’ by a particular set of genetics

As ideas and technology change over time, species have been reconsidered, much like they are when they were first collected and assigned an initial name, sometimes limited to a genus name with the collector’s name and date of collection.  Science proceeds with regular and methodical peer review.  Samples are collected, dissected and described.  Questions raised.  Clarifications made.  Initial designations are just that, tentative.  These original samples are often dried and pressed to be stored for decades in herbaria were they can be returned to and compared to other samples from the same and other regions in an attempt to further refine where a particular plant ‘fits’.  Initial the descriptions in the field might just be macroscopic with perhaps the aid of a hand lens, later scrutinized more closely under a microscope when time and conditions permit.  Today techniques of refined electron microscopy and chromosomal analysis may be used, and connections once made based on physically observable characteristics often superseded by genetic analysis. The Woody Iridaceae.jpg

In a monograph on the woody Irids I found the following sentence, “This is a common feature of leaves of Iridaceae and probably the basal condition for the family.”  Basal, references a basic or beginning structure that underlines and defines the Iridaceae and its included genera.  It should be added here that these may not be readily apparent to the eye, especially to the non-trained.  Different genera, different families, will possess such defining structures.  Species will vary in their particulars, but they will still share these, which tie them together as a group.  The ‘woody’ Iridaceae, are differentiated from the other species in the family by: “‘woody’ stems; two-flowered inflorescence units; long-lasting flowers; a distinctive capsule that usually has one shield-shaped seed per locule, and a remarkable seed coat with a transparent testa”….not all things that are readily observable to the typical gardener or within their knowledge to know that these are the decisive structures that they should be looking at.  These differences are unique enough to land them in a sub-family, along with 3 other genera, which confusingly don’t have woody stems, sharing only their caudex, the Nivenioidae.

Let’s back up a little bit to ‘woody stems’ are these different than those I described in my earlier Monocot posting? and, how did these seemingly random, small group of Irids come to be ‘woody’ when no other genera in the Family have this charachteristic?  How does this happen? Is this capacity lying dormant in the genes of other Irids?  The Iridaceae are in the larger Order Asparagales which contains the woody Cordylines.  Looking more closely at this family, the authors of the Wiki page write,

“The order is clearly circumscribed on the basis of molecular phylogenetics, but is difficult to define morphologically, since its members are structurally diverse. Most species of Asparagales are herbaceous perennials, although some are climbers and some are tree-like.”(Insert shrug here.)

It would seem that in our efforts to be true to a plant’s genetics we may be rendering the classification system much less useful to those of us in the field, or garden, with  neither a lab nor the inclination to parse all of this out for ourselves, at a disadvantage much greater than when classification relied strictly on morphological, or physically observable, structural differences.  This also begins to beg the question raised by some, that maybe genetics and DNA are not sine qua non to living organisms, that maybe there is something additional, in play here. (See “Living Rainbow H20”, Mae-Wan Ho who worked for years synthesizing the work of biologists, physicists and chemists and the current research into the biological function and interactions with cell structure and proteins.) Plants will do what they ‘must’ and will find different paths to get there.

The woody Irids initially grow their stems in a narrow, pinched, structure, later ‘thickening’ them, adding tissue to the flattened sides of new stems.  This thickening does not come from a cambial ‘ring’, there is none in Monocots, but from meristematic cells in the ‘pericycle’ near the primary vascular bundle.  This growth occurs in a radial pattern, that includes additional vascular bundles to support the plant’s growth as it adds more leaves and flowers above.  Woody Irids produce their hard, often brittle stems, growing them into a more cylindrical structure.

(I know, my last posting on Monocots, discussed how they don’t produce such secondary growth….Well, the fact is that, over time, with their different genetics, these Irids do ‘thicken’ their stem and its swollen ‘caudex’ just below the soil, in a way that mimics the cambial growth of Eudicots.  In convergent evolution, plants from different lineages, that don’t share what might seem to be essential DNA, develop physical characteristics of another, unrelated plants.  Outwardly similar, but arrived at from a different ‘path’.  The ‘how do these do this’ part is still being researched and debated.  In some cases there would appear to be something more ‘basic’ driving the development of plants over the long term building off of the given genetics of a plant or group of plants. Structure and capacity are in a sense driven by need.)

When we stop and wonder over an individual Camas or Mariposa Lily, a Coast Redwood or the woody Irid, Witseni maura, it is as if we’ve sampled from a stream of water rushing past us.  This is Witseni maura right now!  Tomorrow, in an incremental, and perhaps an infinitesimally tiny way, it will be different.  When the botanists, taxonomists and systemicists reclassify a species, genus, family or even more basic level of the plant world, the plant itself has not meaningfully changed…only our understanding of it has.  When attempting to ‘classify’ something as dynamic as living organisms, how does one decide, what is a species?  How different must one plant be before it ‘becomes’ a different species?

Populations, Subspecies, Geographical Isolation and Provenance

When we garden, especially when we attempt to grow plants that may require growing conditions somewhat different than our own, perhaps we are marginally too cold in winter, or too hot in summer, we may learn about ‘provenance’, where a particular plant came from, not just its natural range, but where the plant that you have, or its seed, came from…precisely.  This can be very important in horticulture when selecting plants for use because plants from a particular region may have evolved responses to significantly different growing conditions, giving them the ability to tolerate extremes, that those of the ‘type’, those individuals most typical of the species, growing under different conditions, are not.  This can be quite important, for those of us in Portland, for example, with plants like Eucalyptus spp., that may have a individuals that range into higher/colder elevations, effectively increased cold tolerance.  Other populations may range into warmer/milder regions than is typical for the species and possibly be less ‘accommodating’ to colder extremes than the ‘type’.  (When botanists collect plants for examination, they are attempting to describe what is ‘typical’ for the species, they may note some of the variation found within the species, but they are most concerned with the ‘type.  They will also note and describe its normal range to help others when they come across it in the field, noting its growing conditions.)

Climate remains relatively constant over long periods of time, so that the weather in a particular place also exhibits a certain constancy.  To survive a species has it best adapted individuals survive while the others perish.  Over many generations this population can come to vary in this way from the type, its range of conditions it will survive under, altered in this way.  Both its seedling progeny and clones will possess this distinct characteristic.

In some cases this same set of atypical growing conditions will result in a changed appearance.  Often the length of internodes will be shorter in situations where the growing season is shorter, perhaps cooler as well, which often goes along with harsher winter conditions.  The opposite effect can occur as well, where conditions are warmer and growing seasons longer.  Add into this that soil conditions can change in terms of nutrient and moisture availability, and you can have very different plants of the same species.  Presumably, in these cases where the genetics remain unchanged, individuals from this different population, will reflect the physical characteristics of the species ‘type’ when it is grown under more normal conditions.  But, sometimes, when isolated populations grow for a great many generations in one place, they develop different physical characteristics than the type that remain when grown elsewhere.

When in cases they’re appearance or morphology is permanently altered, plants are often separated into a sub-species, closely related, but different enough from the species type, to warrant this more specific designation…I’m assuming here that this finer degree of classification is supported by genetic studies today, but sub-species were identified before our ability to do such testing.  Again, this begs the question what constitutes a species and how much different must one plant be from another before it ‘becomes’ one?  And, the intermediate designation of sub-species, why the finer ‘hair splitting’?  Why not include it in one or another existing species?  And what about the issue of speciation? the development of new species over time? the process of an ongoing ‘creation’?  How and why?  What is involved?  If all life is derived from one source, is all of ‘this’ simply a matter of time, opportunity and changing conditions?  If life is an expression of an organism’s DNA, is all of this just a matter of chance mutations?Sky Islands

Isolation does not always lead to further speciation.  There are ‘thresholds’ and numbers that must be met other wise the result might only be extinction.  If conditions change fast enough, species, each with their  limited capacity to adapt, can be lost…while at the same time providing opportunities for the development of new species…again, if the changes don’t occur too quickly and the gene pool is rich, diverse, not having suffered significant losses.

Species that exist in small numbers, with narrowly circumscribed ranges, are more subject to loss and extinction.  These can be very ancient species like the Cycad family that millions of years ago were one of he dominant groups on the planet.  Now they are in danger of extinction.  Other species, many of our Orchids were never particularly wide spread and are susceptible to extinction from habitat loss in their very limited and shrinking habitats.  Others, such as the many species that occur on the Maderan Sky Islands (click here for a quick introduction to this region) of southern Arizona and northwestern Mexico, have extremely isolated populations on mountain tops separated by wide stretches of Sonoran and Chihuahuan Desert with no opportunity for expansion or even the possibility of moving from one ‘island’ to another due to the distances and the inhospitable conditions of the deserts.  Little worlds unto themselves.  As our climate warms these cooler temperate and more alpine species continue retreating upward until they are squeezed out.  These are outlying populations cut off from the Cordillera of the Rocky Mountains to the north and the Sierra Occidentale to the south, evolving in isolation, while the plants of the two great Mexican deserts spread north, slowly climbing the mountains.

For those of us content to work in our gardens or explore our region’s landscapes this process can be frustrating, even disconcerting.  ‘Why’ we might wonder, ‘can’t they leave well enough alone!’  Those of us who have known a plant under its old name can find it incredibly frustrating to find that the earth has moved under our feet in this way…maybe even a little betrayed.  But those who grow up in the plant world today, won’t have to restructure their memories this way.  There have been a great number of name changes and shifts of plants from one genera or family to another, at least in part due to the DNA analyses of plants in more recent years.  Our many Shooting Stars that occur across the western North America, many of us will always recall first as members of genus Dodecatheon and then have to make the ‘conversion’ to Primula, while thinking, ‘Why, oh why’?  The old designation served our own needs for identification much better than the blurring brought to us by DNA, even though it may be more ‘correct’ and illustrative of a genera’s ability to adapt over time from its closest relatives.  Species are more than their DNA, some of which is recessive or ‘repressed’, some of which is uniquely expressed.

Plants are the physical expression of themselves in the landscape, occupying niches in ‘communities’, fulfilling functions and needs.  DNA, while valuable in tracing a plant’s history and establishing its genetic connections, doesn’t make it more likely that we will grow them better or help us identify them in the field.  We depend upon their morphology to recognize them in our gardens or out in the field and thus to evaluate how they are performing.  If our classification system, if its nomenclature is too burdensome or even unhelpful to us in our learning of plants, how does that help us?

Maybe we require a second system that aids us in our learning of plants and how to grow them, that relies on plant morphology and the physical ‘cues’ that they offer us.  If the difference between one species and another can only be determined through DNA analysis, that is not very helpful to us.  If relying on DNA testing combines groups of plants that are morphologically very different, this can lead the non-expert, most of us, into confusion.  So, again, what is a species?  How is one living organism different from another?  What is it that defines an organism?  What is gained by all of this genetic hair splitting?  Is it just to settle differences between various competing ideas and botanists?  Or, is DNA just a tool, an avenue of study, to better understand the cellular operation of the organism? That is and of itself not the key to truly understanding life?  What if life is more inclusive, wholistic? Not entirely knowable by studying it in its vanishingly small parts.  What is the purpose, ultimately of the classification system?  What do we know of an organism by assigning it a species name?  What does that teach us of its dynamic relationships with place and other organisms?  Maybe, what is necessary to understand, is how it all fits together, what constitutes a healthy plant community?  Maybe we should be trying to understand the essential relationships between animal, plant and place?  What it means to lose a species? to introduce another? the extent to which one ‘species’ can fulfill the role of another?  As we continue to examine life here in its ever tinier details, we are losing millions and millions more acres of habitat, of biome.  Each ‘species’ plays a multitude of roles in its communities…what are they and shouldn’t we be addressing that?

I have long thought that we should be placing more emphasis on the study of ecology, on ‘Systems Science’, looking at plant and animal communities as a whole, how they interact and evolve over time, the many and various roles that they play necessarily in the larger process of life…happening in a place, so that we can understand the processes therein and protect or rebuild what is lost.  Ultimately both approaches are needed.  Our focus on individual lives, on their unique and special qualities, while seductive and inspiring, necessary even, does not equip us with all of the tools and understanding that we now need to be responsible stewards.  We cannot ‘save’ the world in our gardens and zoos of the world if we don’t understand the intimate relationships at play across the many landscapes of the world…and adapt our personal and economic behavior in ways that are more supportive of that life.  Ultimately, conservation of species relies on our ability to conserve and steward our wider landscapes, something we haven’t been particularly good at as a fellow species ourselves.

All of this gives me reason to pause and consider what is happening in the world, biologically, what ‘we’ are doing that impacts the lives of individuals, entire species and the life on this planet…so much is in flux right now.  Species, however we define them, are under unprecedented ‘pressures’, declining in numbers, experiencing a highly accelerated rate of extinction.  The places which are suitable for any given species, are being transformed into human landscapes that directly support our consistently increasing population.  We have altered the conditions under which species have lived in such a way as to support our singular and short term increase.  We have converted earth’s landscapes into resources for our use and consumption to an unprecedented degree and in so doing are degrading, transforming and consuming them, ‘holding’ others in limbo for future development or as indeterminate wastelands, generally with little regard for those species that remain on them or are being extirpated.  The climate is warming effecting even those in otherwise little disturbed places, effecting the seasons and availability of water incrementally and catastrophically, the conditions under which diseases and pest may flourish…all of this while many argue that such changes are inconsequential and exaggerated, out of ignorance and selfishness, insisting that it makes little difference.

So, what is a species and why does it matter at all how, or even whether, we choose toHalf Earth wilson.jpg classify them?  It matters, because we are a culture of ‘experts’ and , in so doing, we have made the living world a little less approachable, less understandable, separated it from us. Living organisms, are in the realm of experts, not really part of our world.  We, as a people, have lost our sense of connection, our relationship, with the world around us, along with its care and the decisions that effect its fate.  That is ‘job’ of other experts, of politicians and property owners, the powerful, who too often also have little to no understanding of what damage their decisions are inflicting.  We charge others with the care of our public lands, assume that they possess both the knowledge and the intention to do so, while their purpose, their mission, is decided by the powerful who daily demonstrate their ignorance and priorities that continue to sacrifice this same life. They charge our land managers with the care of these places and demonstrate their low estimation of their value by giving them inadequate budgets to do so effectively.  While our role has been reduced to ‘user’ or ‘consumer’.  It matters because in a culture of experts, in which we bear little of the recognized responsibility and a poor understanding of the problem, we trust that our priorities and needs are being recognized and protected.  We assume that our needs will be met by those in charge.  And while the botanical or ecological experts work to better understand the value of this world and how it works, that world and we along with it, find our future more perilous.  These particular experts, the botanists and ecologists, possess only their limited voices and the ability to inform and teach.  It is not so much that what we call something matters, but our recognition and our valuing of it, that does.  While I can immerse myself in the intricate wonders of a given species, our practice of focusing so much on details, details that most ‘modern’ humans are both ignorant of and blind to, adds to the divide between the living world and the masses of humanity that threaten it.

What is a species is a question that must address an organism’s value to the ongoing miracle of life.  It must address the relationships between organisms and the places they depend upon, even what their existence, or absence, means to a place and the other life which depends upon it.  A species is not a self-contained entity that can be considered, given a value and then simply utilized, protected or ignored as some disconnected resource or input, here to meet a direct human need, to be consumed and forgotten by business.  Such a devaluation of species, and life, ultimately speaks to our own value in the larger picture as well as to our ignorance of our absolutely essential role as a species ourselves.  What is a species??? We can only begin to understand that when we are able to put ourselves back into the question and recognize the essential nature of all species in the continuing processes of life on this planet.  Our willful ignorance cannot protect us from the consequences of the actions of our species here.  We are disrupting a billions of years old process, the result of which will be our demise as a species, if we are ‘lucky’, the struggling survivors of some apocalyptic real world nightmare.  We are not above the consequences to our actions. Our ignorance will not absolve us.


4 thoughts on “What is a Species?

  1. Erin Boyle

    You actually make it seem really easy with your presentation but I to find this matter to be actually something which I feel I would never understand. It kind of feels too complex and extremely extensive for me. I am looking ahead for your next publish, I will try to get the cling of it!


    1. gardenriots Post author

      It is complicated! I’ve been a horticulturist and worked in the landscaping field for most of the last 40 years, but until recently haven’t really looked into this in any detail. Still, if you’re patient, there is something to learn for any of us in attempting to understand this.


  2. TIm Huntington

    As always, great writing. I highly recommend checking​ out the work of Timothy Morton, in praticular his book “Dark Ecology”.



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