Botanical Keys for Citizen Scientists


  1. Humans have altered every aspect of planet Earth, but we neither understand the natural world we inherited nor the new systems we haveproduced.
  2. Because we now truly manage this planet, comprehending the new natural history of Earth is yet more vital thanever.
  3. Professional scientists will never have the resources or capacity to make sufficient observations to document and explain the new natural systems on which we all depend and with which weinteract.
  4. Citizen scientists can contribute to the need for greater understanding and appreciation of this world that is home to all living creatures.
  5. Basic field skills and botanical understanding can equip any interested citizen to make observations, generate useful data, and collaborate with others to increase our communal knowledge about the nature and future of life on Earth.

When I was a child, most field study had become the province of professional scientists – researchers working out of Universities, or the Extension System. The day in which a dedicated amateur could make solid contributions to our understanding of nature seemed a relict of the 19th century.

But over the past several decades, botanical research in the traditional academic settings has shifted from descriptive study to more technical and technology-based investigation, with a goal of generating the molecular and genetic understanding that underpins and advances knowledge.

Scientists know there remains serious need for field work – descriptive and ecologically-based studies that can provide observations and data about both natural and built communities.   Gathering and reporting that kind of information is becoming the job of contemporary Citizen Scientists, most of whom will find plant naming, identification and collecting techniques are a solid and necessary basis for understanding how to work with plant information in every situation.

I would guess many people interested in natural history and citizen science already know quite a bit about plants, including plant identification. But plant names and the categorization of plants (taxonomy) are as much artifact as judgement, so history is a key player.

Let’s go through some main issues about plant names:

  • Taxonomy, the naming of plants, is a difficult matter (apologies to T. S. Elliot), with the overriding purpose of establishing a single, globally-valid name for each recognizably distinct species (and variety) on Earth.
  • Plant taxonomy differs from almost every other realm of botany in that publications never lose value or become irrelevant.    It makes taxonomy a bit stodgy but even that is useful.
  • Taxonomists worldwide agree on rules by which plants are named. Those rules change over time, but the system for establishing them is decades-old, and international. Even during the height of the Cold War (if you are old enough to know what that means), delegates from countries like Cuba and China participated.
  • Plant naming and documentation of plant variation and distribution depend on evidence, vouchers, in the form of preserved specimens. We follow the type system, in that each plant name, in the end, is irrevocably tied to a physical specimen – termed the type for thatname.
  • Even as researchers continue to explain evolutionary origins for different clades and plant species, we accept the practical need for every plant to have a name that connects to historical literature. Each different plant is a specific kind (a species) within a general and definable group (a genus).  Both categories, genus and species, have their roots in philosophical discussions from the early enlightenment. The resulting binomial becomes the key to accessing all published knowledge of any plant.                                                                   

Think a bit about the origins and meanings of these rules. Culturally, worldwide, there have been many takes on plant knowledge and naming of plants. At one time, knowledge of plants in ancient Egyptian and Asian cultures probably greatly exceeded the level of plant appreciation in Western Europe But we have to accept the fact that science, as we know it today, is based on European practice that emerged between 1500 and 1700.

Core to the European traditions were Greek, Latin, and Arabic teachers and texts in fields of math, astronomy, physics, medicine, and agriculture. Because plants were society’s pantry and medicine chest, physicians and farmers, informed by advances in other sciences and technologies, slowly crafted an understanding of plants that underlies botany today.

Throughout the world, there seem always to have been people who specialized in curatives. This required personal knowledge of local plants (as well as animals and minerals),in that most cures came from nature’s cabinet of wonders. And certainly there were early systems for naming or referencing plants, but specifically in Greece and the surrounding Mediterranean basin, by 300 AD, there was a written flora to useful plants. The Materia Medica, ascribed to Greek practitioner Dioscorides came into circulation and through migration to far reaches of the Mediterranean world, Dioscorides’ text became standard.  And it had real legs. For nearly 1500 years. even into the the early days of true modern science, any compilation or herbal used by physicians and practitioners in Europe was a translated adaptation of the Materia Medica. We are told those herbal texts were second only to the Holy Bible in copy and print numbers.

But there was a problem with the Greek text. It held up in areas very similar in climate to Greece – from the Levant to Spain. But the temperate plants to the north, the floras of Germany, northern France, Holland, Belgium and the Scandinavian countries, are simply too different – giving botanical meaning to the phrase “it’s Greek to me.”

I have to imagine that people in the colder regions of Northern Europe had a lot of indoor time during which to ponder their texts and studies, because it is clear that as the Renaissance moved northward from its Italian origins, interest in plant science blossomed. There was no option – in those lands Dioscorides’ text was fairly worthless. Plants and circumstances in Germany, Austria, and northern France were different. People needed the authority of Dioscorides, but were forced to examine and expand the materia medica. Works such as Brunfels’ 1530 herbal and Fuchs’ 1542 included valid illustrations, drawn from living material rather than being copied iconographically. This was not isolated change, rather reinterpretation of ancient texts developed in the greater context of the printed word (Gutenberg, 1455), exploration of the New World (Columbus, 1492), and opening of a sea route to India (Vasco de Gama, 1497). The 16th century was a time of change, brewing with intellectual growth.

A century later, the scientific world had come alive with cataloging and discovery. Economically useful plants were making their way around the world; South African garden plants were cropping up in Europe. Herbals and catalogs documented these new plants, but without the advantage of standard names, or even conventions to create names. The Bauhin brothers came to the rescue, publishing their grand compilations. Caspar Bauhin’s Pinax was available first, in 1623, summarizing the works of herbalists. But systematics (mainly in service to medicine) was not the only area for advancement. Fresh knowledge came regarding how plants function and how they are constructed. Robert Boyle, 1661, published his studies as The Sceptical Chymist in 1661. Robert Hooke described the first cells with his 1665 Micrographia, and by 1694 Rudolf Camerarius had determined that plants have sexual organs and lifestyles.

But systematics was being challenged the most. Gardens and cabinets were filled with exotic plants; evidence that a new system would erupt, which it did. With an air of predestination, the new order was codified through the publications and popularity of Swedish botanist Carl Linnaeus. His system was overarching and simple. It brought instant capacity for standardization that an almost trivial aspect, his decision to assign every specific kind of plant to a genus, and and then append a specific epithet (what we call the species name), persists as the system for naming plants today. And Animals. And other life forms.

“For Andrea Cesalpino in the sixteenth century, the task of identifying plants looked so daunting that he compared it to going to war agains ‘legions of monstrous Plants.’ In De Plantis (1583), the first of early modern efforts to systematize the plant kingdom, Cesalpino declared that plants must be organized into categories “just like the battle line of an army,” for otherwise “some plant might by chance escape our notice, and, in a way equivalent to those soldiers which at times move on to different groups, a plant can be placed in a category to which it does not belong.’” from T. M. Kelly, 2012. Clandestine Marriage, Botany & Romantic Culture

The proof is in the pudding. Linnaeus’ seminal catalog, Species Plantarum, remains the foundation for authorized plant names today. His “L.” is the authority for thousands of taxa, mostly plants that are part of our European heritage. From Pisum sativum L. (Green Pea) to Quercus robur L. (English Oak), Linnaeus staked his claim.

So what is in those names?

First, a scientific plant name (a binomial, i.e. genus and species) implies a concept – it says that we know a name (which is tied to a physical specimen – a type), and that name represents something we can define as a species. Well that’s a problem. People may really disagree as to the limits of one kind (species) of plant as compared to another, because they may actually accept differing definitions as to what segregates one species from another.

In Linnaeus’ day, plants would be grouped based on pure form – visible and quantifiable characteristics that tie to a definable geographic distribution would be diagnostic. Given extensive study and experience, someone like you, as a naturalist and taxonomist, would group like with like, and come up with piles of specimens and notes corresponding to an idea of identifiable species. After determining which of those have valid names, you would give new names to the remainder and voila – you have monographed the group and discriminated the various species.

The limits to that method come when characteristics are not clear cut, as with oaks, which are known to hybridize readily. Indeed, I remember someone joking that with oaks you could either name the species or name the hybrids between them all. In either case, there would never be certainty .

Most people today would probably acknowledge that reproductive isolation is one reasonable criterion for what makes a species. Plants that are reproductively part of one population (regardless how limited or widespread the distribution) that mostly remains discrete from other populations would be part of the same species. But this distinction requires extensive knowledge of populational characteristics and behavior, reproductive biology, and autecology. It is the basis for the biological species construct, but the assumptions become suspiciously theoretical in many instances.

Searching for the holy grail, botanists have always felt that once we understand the genetics of plant groups, it will be possible to correlate species with evidence of genetic relatedness and separation. Such work, though increasingly possible and accomplished, doesn’t help the field biologist who needs a practical way to identify plants so as to tie their observations to the kinds of plants encountered. For all we know about the plant world today, the simple need to understand how we can identify and talk about different kinds of plants remains paramount.

And at that level, things have not changed so much. You need to know the plants in your area, which means you will want to know what resources exist that can help you identify those plants. In the best of worlds, you would have access to a comprehensive, up-to-date, and practical flora. For decades, people around Los Angeles have relied on the Manual of Southern California Botany (1935) and later A Flora of Southern California (1974), both by Philip Munz, while folks from Northern California leaned on Jepson’s 1925 Manual of the Flora of California. Today the most active update underway is the Jepson Flora Project coordinated through the Jepson Herbarium at UC Berkeley. A print version of The Jepson Manual was published in 2012.

But floras are funny. They have to work for you, so the proof is in the pages. Floras propose to help you decide the identity and potential distribution of a plant by “working the keys” and reading the descriptions. But a Flora is really a puzzle, a paper calculator and catalog meant to be manipulated. And it is arcane. When you open a flora to use the keys, you enter a binary world, marching through paired choices to get to a family, and then to a genus, and finally to your goal – a species. The hardest part of most keys will be the entry levels, where you have to wade through all sorts of necessarily vague choices to get to the right track that (in California) would take you to the correct one of 8,000 taxa. But it never really gets simple.

Unfortunately, beginners have the great challenge in this regard because the more you know about plants, the more you can skip the hardest part. It’s like getting a bye in a tournament.

The good thing is that cheaters prosper – it is totally fair to use any resource available that gets you to the correct identification for a plant, thus connecting you to the world of information about that plant.

When someone (or some local flora with good photos or drawings) gets you to the right identification, then you can go straight to the written description in the flora. Eventually, you will have working knowledge that helps make the keys make sense. A great way to gain a sense of Jepson or Munz is to look up a common plant you may know well – like Quercus agrifolia. Read the description. Examine theillustration.

Go to the key. Reverse engineer it, examining the plant and tracing the choices backward. This exercise is a supreme revelation, payback for that assist you got from photos and guides.  Would you have been able to work the key through to the end? Where did you find issues that might have caused problems?

I found this revealing. Munz’s first choice (dichotomy) in his Quercus key separates the Black Oaks from the White Oaks – with the opening line: “Bark dark, not scaly” as contrasted with “Bark Light, scaly.” The scaly part works when I compare Quercus agrifolia to Quercus engelmannii, but the dark bark vs. light bark doesn’t make much sense to me.

Moreover, the bark of Q. agrifolia near Monterey, CA looks very different from Q. agrifolia bark in Pasadena. Jepson makes the same break (between Black Oaks and White Oaks), but the opening salvo is “Cup scales thin” as contrasted with Cup scales generally thick. If you know little about oaks, and have no other oaks for comparison, the choices are unanswerable. However, if you think you know the plant, the key and descriptions become infinitely useful. The flora becomes an instrument to help you confirmidentification.

And it becomes more useful over time, as you begin to understand what the author was seeing and how those observations play out in words.

You will begin to realize that a great flora helps in other ways, by highlighting diagnostic characteristics in a description for example. And a good key will give as many useful clues as possible.

So where do things stand? Are there good floras for plants around the world. Surprisingly, there is no such thing as a world flora. In fact, work is only now underway for a consolidated flora of North America. Unfortunately, that flora will exist only in time to document the great extinction human activity has precipitated.

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