Plant Names

Names for Plant Species

Why Use Scientific Names?

The basic point of the following discussion is that scientific names are standardized world-wide, must accompany a specimen of the species they name, and therefore are accurate and facilitate communication about plants; common names have no standardization, do not accompany a specimen, and therefore are inaccurate and confuse communication.

Each person makes the decision about how accurate and detailed they want to be in understanding plants.  Some of us are happy knowing "Oak".  Others want to know what kind of Oak.  Others want to know all the details about Oaks.  Start where you are comfortable, keep your options open, and see where you end up.  

Following is a brief summary about what common and scientific names are and why, especially if you want to really understand plants, common names should be avoided and scientific names should be used.

Detailed discussion of common and scientific names.

Common names have no standardization even in small local areas and thus common names vary from person to person, state to state, region to region, and country to country. Even at the family level, there is confusion in common names.  One person says "Sunflower", another "Aster', another "Daisy", and another " Composite".  Some people say "Peas", some "Beans", some "Legumes" or "Vetches" or "Milk Vetches".  The name "Lady Slipper" is applied to a number of different Orchids; the name "Chickweed" to many different species; the name "Primrose" to members of entirely different families.  And all those thorny guys are just plain "Cactus" -- whether they are cylindrical or flat, Yuccas, or spiny shrubs.

If you want to purchase more of a plant you admire, or if you want to work toward the protection of that plant, or if you want to learn more about that plant, you will need the exact, unmistakable scientific name.  There is no such thing as an exact, unmistakable common name.

Following are some of the cons and pros of common names.  (Sorry, the cons by far outweigh the pros.)

1) Common names are made up by anyone for any reason and are not recorded or attached to a preserved plant specimen.  

2) In almost all instances it is impossible to find out who gave the common name, when they gave it, what it means, and, most importantly, exactly which plant it refers to.

3) There is no standardization of common names.  There are few if any books that list common names with details about the precise characteristics of each plant so we can know for sure what plant is being referred to.

4) Common names do not show relationships among plants.  Your last name is your family name and shows relationship; a plant's scientific name places it in a group of similar plants with the same name and this shows relationship.  Common names rarely share the same words and thus do not show relationships.

5) Most plants have no common name. (Now that’s a very good reason for not using common names.)  Remember this when you look at plant identification books.  Most authors will tell you that they have made up a number of common names just for publishing in their book.  Very often that made up common name is just a rearrangement of the scientific name, for instance, the scientific name Phacelia fremontii becomes Fremont's Phacelia.

6) Plants with common names always have several common names because names vary from person to person, region to region, and country to country. Thus, using common names frequently leads to misunderstandings and arguments.

7) In a number of instances, the same common name refers to several different species, not to one specific plant: There are many "Bluebells", "Paintbrush", "Goldenrod", "Daisy", "Groundsel", "Geranium", "Chickweed", "Fir", "Pine".  So if you want to know the name of a particular plant and someone tells you "That's a Paintbrush", they have just helped you about as much as someone telling you that man's name is "tall human being";  there are many different kinds of Paintbrush and many different people who are tall.

8) Some totally unrelated plants have the exact same common name, for example, the "Skunk Cabbage" of the East and the West.  The same confusion reigns with many other names:  "Bluebells", "Lily", "Buttercup", "Shooting Star".

9) Plants in the Southwest United States have Spanish, Native American, and English common names.  Which common names should be used?  The truth is that they are all jumbled together and in the Southwest it is common to walk a trail and refer to one plant by an English common name (Elephant Heads), the next plant by a Spanish name ("Osha"), and the next by an Indian name ("Chuchu pate").

Where do common names come from?  As I indicated above, anyone can make them up.  People make up common names to refer to some real or imaginary aspect of the plant.  Some common names refer to a perceived visual (often color) characteristic of a plant ("Bluebells", "Golden Glow", "Baby’s Breath"), or are some part of the scientific name ("Geranium", "Delphinium", "Aster", "Whipple's Penstemon", "Engelmann's Cactus"), or are derived from human names ("Black-eyed Susans", "St. John’s Wort"), or refer to a plant’s resemblance to another plant ("False Solomon’s Seal", "False Hellebore"), or are given because they remind human beings of something ("Butter and Eggs", "Monkey Flower"), or are assigned for some real or imaginary medicinal property ("Lousewort", "Self-Heal").

Overall, then, a common name should be used with caution, realizing that each name frequently refers to several plants, not to one plant, and that the common name varies from person-to-person.

Having said all these negative things about poor old common names, let's look at the advantages of using them.

1) Because our common names are almost always in English, our native language, they are easy to pronounce and, therefore, easier to remember.

2) They sometimes have a charm about them: Blue-eyed Mary, Cone Flower, Baby's Breath, Indian Paintbrush, Chiming Bells, Perky Sue....

3) Although I have pointed out that one major problem with common names is that they vary so much, there are some common names that are fairly standard and widely understood:  Oak, Pine, Sycamore, Ash, Dogwood, Mullein, Thistle, Poison Ivy, etc.  But most such standard common names refer not to one particular plant but to a group of plants.  If your favorite Oak tree dies and you go to a nursery to buy a replacement, it won't get you far to say, "I want an Oak".  You need at least to know "White Oak" or better yet, "Quercus alba".  That way you will get exactly what you want.

My wife and I have special common names that we have assigned to a few plants and we do use these names occasionally  --  in a whisper only to each other.  

Overall it should be remembered that the point of names is to facilitate communication.  Common names will not do that.

The common names that I give in this web site are those that I have heard most often associated with that plant in the Four Corners region.

Scientific names are in Latin and/or Greek, are assigned by botanists to plants, and are accepted internationally, i.e., the exact same name is used for the plant in China, South Africa, Chile, and Canada.

To be accepted, a scientific name must be placed on a collection sheet with the original plant (the type specimen).  The name must be published in a book, botanical journal, newspaper, magazine, or accepted web site along with a detailed description of the plant.  From this information future researchers can always find out who collected the plant, who named the plant, when they collected and named it, and the precise characteristics of the plant.  For an example see this page on my web site.

Most importantly, future researchers can see the actual plant, for the plant is preserved in a herbarium. Herbaria are now putting photographs of their specimens on-line so a wider audience has access to them.  Click for an example of a virtual herbarium.

The scientific name for a plant, i.e., the name of the species, is always two-part, two words.  The first word designates the "genus" to which the plant belongs and the second, called the "specific epithet" or "species epithet", or "species name", gives a name to distinguish this plant from all others in the same genus.  For example, in the name Senecio serra, "Senecio" is the genus and "serra" is the specific epithet.  Senecio serra is the name of the species.  There are many other Senecios but only one Senecio serra.  No other plant in the world has the name "Senecio serra".

All "Senecios" are members of the Sunflower Family, scientifically called Asteraceae.  All Asteraceae share a number of similar characteristics.  Members of Asteraceae that share a smaller number of very similar characteristics are grouped into genera.  Each genus is comprised of a number of species that share an even smaller group of similar characteristics.  And finally, each species has some significantly different characteristics that sets it apart from all other members of the genus and thus from all other plants in the world.

Both the genus and the specific epithet are italicized; the genus is capitalized and the specific epithet is lower case: Senecio serra.

Scientific names describe a characteristic of the plant (hairy, short, twin seeds), show a relationship to other plants (similar to a plant from another country, similar to another genus), honor a place or person (see the Biographies of Naturalists section of this web site), or are derived from history (an ancient use or the name of an ancient country where the plant was first recorded).

The scientific name almost always appears as only the genus and specific epithet, e.g., Senecio serra, Arnica cordifolia.  But the full scientific name includes the author's name and the date of publication of the description, e.g., 

Arnica cordifolia Hooker 1834

This means that the plant was named and described by William Jackson Hooker in 1834.  Having this information leads one to the written material where the plant was first described and named and then one can find out where the plant was collected, why the name was given, who collected it, and all the details of the plants structure.  

Note that the person named after the plant name is not necessarily (in fact, most often not) the person who discovered the plant.  Arnica cordifolia was discovered by Thomas Drummond and he sent it to Hooker to describe and name.

There are a number of other variations in the appearance of the scientific name:

a) Picea engelmannii Parry ex Engelmann 

This means that Parry named Picea engelmannii (what we commonly call Engelmann Spruce) and sent the specimen and name to Engelmann who published the description with the name Parry suggested for the plant.  Note that although the plant bears Engelmann's name, he did not discover it or name it.  It is common for a plant to be named to honor a person -- perhaps even a person who never saw the plant, although in this case, Engelmann did see the plant named for him when he traveled to Colorado (a number of years after it was discovered by Parry).

b) Calypso bulbosa (L.) Oakes 

This means that Linnaeus first named this plant but the name he gave (which is never shown, but in this case was Cypripedium bulbosum) was changed by Oakes to reflect more accurate classification.  The person who first names a plant always has their name attached to the plant even if the plant name is changed.  If someone else were to come along and change Oakes' plant name, Oakes' name would be dropped:

Calypso linearis (L.) Smith

As this last point indicates, scientific names change: new research can show that a plant was originally mis-classified.  Unfortunately there is no national or world-wide group that reviews research and publishes THE most up-to-date scientific name.  If a researcher believes that they have found evidence that plants should be regrouped and renamed, they published this evidence and it is gradually accepted or rejected by peers.  This means that several scientific names might be used for the same plant at the same time while waiting  for time to settle the dispute.  This is messy, confusing, and irritating.  But at least these alternate names are always linked and published together so even though the scientific community does not agree on one name as THE name, we do know the two or three choices.  (Click to read further discussion of this under "Synonyms".  And click to read a nice, short explanation by the Royal Botanic Gardens, Kew, about why names change.)

A very hopeful sign is that over the past several decades more and more regional and national floras have been developed and made available on the web.  These floras are going a long way in helping to standardize scientific botanical names. 

To facilitate communication it is important to have one text as the basis for your scientific names. The first name that I give for every plant in this web site is that designated by John Kartesz in his Synthesis of the North American Flora (available as a DVD soon). The Synthesis plant names are shown in bold. 

William Weber's Colorado Flora: West Slope is the best and most often used field guide to the plants of the Four Corners region, so I also always show his plant name, but when it is not the same name Kartesz gives, I show Weber's name as a synonym.  Other synonyms are also shown in normal, non-bold, font.

In most instances the Synthesis plant names and Weber's plant names are the same, and these names are also frequently in accord with the names on the USDA Plant Data Base and in the Flora of North America, although the former is unfortunately swamped with unrecorded data and it is too often outdated.

Click to read a story about the complexity and difficulty of naming plants: "The Story of Naming Engelmann and Colorado Blue Spruce".

Pronunciation.  Once expert botanists have placed a plant in its niche and assigned a name, the rest of us must deal with pronouncing the name.  For many people this is a perplexing and intimidating task.  It is a prime reason we balk at using scientific names.

William Stearn, considered the authority on botanical Latin (his book Botanical Latin is the standard) states,

Stearns gives three basic principles for pronouncing scientific Latin: "The pronunciation of a word is determined by the sounds of the individual letters, the length (quantity) of the vowels, and the place of stress (accent )".  

Stearn's points are fundamental and pretty easy to follow for proper pronunciation: 

1) Pronounce every vowel.  

2) When a person's name is part of a scientific name, pronounce it as close as possible to the actual way the person would say their name.  At times, though, this is in conflict with other fundamentals of Latin pronunciation or just sounds awkward.   Follow Stearn's Law: Sound pleasant; be understood.

There are many exceptions to and variations on the following points, but I still find them useful to remember.  

Stearn points out that there are two distinct methods of pronunciation:

a) "Reformed academic" in which the long vowels a, e, i, o, u  are pronounced ah, a, e, o, ooh (as the u in brute).

b) "Traditional English" long vowels are pronounced a, e, i, o, ooh.

I find that most botanists and amateur botanists strive for the first pronunciation, but as I listen, I find that everyone mixes "reformed' and "traditional", e.g., I have not heard anyone pronounce Asteraceae in the strict reformed academic style (which would require that the "ae" at the end of scientific family names be pronounced as the "ai" in "aisle" and the "c" be pronounced as the "c" in "cat").  Thus Asteraceae would be pronounced  :  "ah  sterrrr ("r" is trilled) ah  cuh  a   i".  

I personally pronounce family names with "traditional English" pronunciation so that the "aceae" that ends all family names is pronounced  a (as in ace)   c  (see)  e  (as in  street): 
Ass ter a c e,    Scrow few larry a c e,    Fab a c e,    Juh ray nee a c e. 

One final fundamental: Very often the stressed syllable is the next to last one.  There are exceptions.

Do your best at pronouncing the scientific name and you will be understood.

Many scientific names have made their way into the common name vocabulary: Geranium, Delphinium, Aster, Gentian, Orchid, Penstemon, Saxifrage, etc. There really is nothing so difficult about pronouncing, or remembering, scientific names. Kids readily do it.  Mind-blocks stop the rest of us from doing it, but once we attempt it and master it, we find that it allows us to understand plants better and communicate about them far more readily.  

Master scientific names and you can walk a trail, meet someone who speaks a foreign language, and the two of you can still talk about plants.  Chinese scientific names for plants are the same as English names.

Synonyms:  Scientific names can change. Continued study of a plant may show the plant to have been incorrectly classified, and the plant may be given a new name, reclassified in a different genus, or even put into a different family.

Although a plant may have had various scientific names attached to it over the years, only one name is currently accepted by the author of the book or web site you are using. The previously accepted names are called "synonyms".  This is a special botanical use of the word "synonym", for in standard usage "synonym" means, "a word having the same or nearly the same meaning as another word".  Such synonyms can often be used interchangeably.  But botanical synonyms are not interchangeable.  Only one name is accepted and synonyms should not be used as a substitute for the currently accepted name.  Lists of synonyms can be found on-line (on this web site, for instance) and in detailed botanical books.

This all sounds very precise and very orderly.  Unfortunately it isn't.  Plant authorities often do not agree on what the name for a plant should be; one authority's name for a plant may be another authority's synonym.  Such is the case for a number of plants in this web site.  As I indicated above, having a number of scientific names floating around at the same time is messy, confusing, and irritating.  The botanical community needs a regional, national, or international committee to review proposed name changes and issue a list of currently accepted names.  Lack of funding, lack of interest, and petty pride and politics have stopped this from happening.  Perhaps egos have the most to do with it: There isn't much of a drive to standardize scientific names when scientists say, "Well that's the name I learned for the plant when I was in college, and that's the name I'll stick with".  Or, "I'm the authority on plants in this state and I'll use whatever names I think are best."

I try to steer through this mess on this web site by using first, in bold, the plant name given by John Kartesz's Synthesis of the Flora of North America. Kartesz's Synthesis (available soon as a DVD) describes plants, provides over 150,000 photographs, and gives county by county records of every plant in North America.) 

William Weber's Colorado Flora: West Slope is the best and most often used field guide to the plants of the Four Corners region, so I also always show his plant name, but when it is not the same name Kartesz gives, I show Weber's name as a synonym.

Because of all this mess, using scientific names may seem to be as confusing as using common names.  It is not; there is always a trail to follow with scientific names.  If the scientific name you see in a book is unfamiliar, you can always find the synonyms for it.  This is impossible to do with common names.

Let's look in more detail at how several scientific names get attached to one plant.

One way is very common even today: an expert on a genus concludes after years of thorough research that several members of this genus really belong in a different, perhaps even new, genus.  Research does take time to get disseminated, reviewed, and accepted.  While this acceptance is coming, some botanists may continue using the old genus name.  Three examples from this web site: the genera Gilia, Arabis, and Senecio.

Another scenario:  Imagine that you are a collector in the Colorado mountains in 1840.  You are an accomplished, experienced botanist so you take it upon yourself to name and describe the plants you have been collecting.  You find that one of your plants is unknown to you and you give it a new genus name -- but here in the wilderness you do not have access to the latest botanical books from Massachusetts and London.  Years later, you or someone else reviews your collection or compares your description with previously published descriptions and it is realized that your plant had been found and named prior to your naming it. The earlier name is accepted.  The name you gave the plant is now just a synonym and no longer accepted.

The same scenario has been played out with many variations, for instance, the botanist/classifiers in Massachusetts might receive a collection from you and find several unknown specimens.  They search all available literature, find no reference to the new plants, and, therefore, give them a new genus and species name.  But the same scene was being acted out in London at Kew Gardens from a collection returned to them by a collector they had financially supported.  They find the same new plants that you in Massachusetts had just given new names.  They give the plants new names.  Which are the accepted names?  That will be based on The International Code of Botanical Nomenclature, 2005 which states that the earliest name takes precedence.

Another very common scenario is the misnaming of a plant: someone in Massachusetts assigns the plant to the genus Aster but a later examination of that plant (the "type" specimen) shows it to be a Townsendia.  Aster becomes just a synonym. (This is precisely what happened with Townsendia.)

Finally, here are two common misunderstandings about names:

1) The person who finds a plant, names the plant.  Not necessarily so.  Usually not so.  Most plants are collected by one person, named by another.  Some people like collecting and roaming the hills, some like studying minutia in an office.

2) The person who finds a plant gets the plant named for them.  No.  About 75% of the plants on this web site are named for a characteristic (hairy, smooth) of that plant, or for the place the plant was collected (Missouriensis, Virginiana, Canadensis), or are derived from history (the name might come to us from an ancient country), or show a relationship (similarity to another species).  When the plant is named for a person, it may be for a person who never saw the plant, it may be for a famous person (botanist or not), or it may be for the person who collected the plant.

There must be some standard at each moment in time so communication can proceed.  Scientific names of Colorado plants in this web site are based on William A. Weber and R. C. Wittmann's Colorado Flora: Western Slope, 2012 edition.  A complete list of the names of Colorado flora is available on-line:  Weber, W. A. and R. C. Wittmann, Catalog of the Colorado Flora.  An examination of the name changes that Weber has made will reveal that almost all are not inventions of his.  He has gone back in botanical literature and accepted a name that at one time was assigned to the plant but is now considered a synonym.  His reason for accepting the earlier name is often the same: to separate species, genera, and families into distinct units.  Weber believes that each species, genus, and family should be clearly separated from others and Weber believes that in a number of cases plants have been lumped into the same genus or family when in fact they have significant differences.

Most common wildflower books rely on some regional botanical authority's detailed book for their plant names, and it is in this book, not the common wildflower picture book, that you will find the accepted scientific name and its synonyms listed.  Most scientific plant names are agreed on and are identical from one book to another, but when there are differences (and many plants have had a number of scientific names over the years) you will find that common wildflower picture books are least likely to have the presently accepted scientific name, regional authorities are much more likely, and constantly updated on-line data bases are most likely.

I rely on John Kartesz' Synthesis of the North American Flora as the ultimate authority. Synthesis names are always bold.

The most widely accepted authorities for the names of plants in the United States are the Synthesis of the North American Flora (available soon on a DVD from the Biota of North America Program), the USDA Plant Data Base, and the Flora of North America Project.

For details about the standardization of plant names see the on-line International Code of Botanical Nomenclature.

Recent genetic analysis has led to many major changes in plant classification.  Numerous families and genera have been rearranged and will continue to be rearranged in the near future.  You can read about these changes: in the Utah Native Plant Society newsletter and on the Missouri Botanical Garden web site.

See Descriptions and Type in the Glossary for further discussion.

A Brief History of Scientific Names 

Plants have, of course, been named for thousands of years.  Before the written word, the verbal naming of plants allowed people to communicate about a plant's location, uses, dangers, etc.  From the time of the Greeks (especially Aristotle and his student Theophrastus) written plant names were grouped and classified based on a system that served their purposes of the ordering of nature, gathering and using plants for medicinal purposes, etc.  For several centuries these systems formed the basis of plant classification until Dioscorides wrote his De Materia Medica (c. 64 A.D.), which classified over 600 medicinally used plants.  Dioscorides' work remained the cornerstone of Western plant classification until major cultural changes came to the West in the 1500's: science bloomed, explorers brought thousands of new plants from around the world to be classified, and interest grew in learning about all plants (not just medicinal ones).  Because of all this, the old systems of lengthy, non-standardized names were found to be unworkable.

Many individuals attempted to provide a more workable classification system.  Of major importance was John Ray (1627-1705) of England who in 1682 wrote Methodus Plantarum which promoted the species as the ultimate taxonomic unit and utilized for the first time the categories "monocotyledons" and "dicotyledons".  From 1686-1704 Ray published his master work, Historia Plantarum, a three volume work on over 18,000 plants.  In these volumes Ray broke with past classification systems by grouping plants on the basis of a number of their characteristics; until Ray (and after him for many years) plants were grouped according to one major characteristic such as the color, flower structure, or medicinal use.  Many of Ray's family groupings are still with us.

Carl Linnaeus (1707-1778) of Sweden built upon the work of Ray and many others and is now credited with providing the foundation of modern taxonomy.  Classifying was a natural outgrowth of Linnaeus' youthful collecting of plants, his position as a Doctor (medicines were, of course, plant-based then), and his interest in introducing new plants to benefit the economy of his native Sweden. 

Unlike Ray, Linnaeus set up his categories of genus and species solely on the basis of floral parts: class was determined by stamens and order by pistils.  This method placed very different plants in similar groupings and taxonomists eventually abandoned the floral groupings in favor of methods proposed in varying ways by John Ray, Bernard de Jussieu (1699-1777), Augustin Pyramus de Candolle (1778-1841), Antoine L. de Jussieu (1748-1836), and others; work of these individuals led to classifying by examining the entire plant, not just the floral parts.

But Linnaeus' use of hierarchical classification and binomial nomenclature remains the basis of our present classification system.  Linnaeus took each grouping of plants and placed it under another grouping of plants that shared similar characteristics. Over the last centuries taxonomists have changed and rearranged some of Linnaeus' groupings but we still retain the basic Linnaean structure.

Linnaeus also remains important because of his world-wide view of botany.  Many of his students went on world explorations (his student, Daniel Solander was the naturalist on Captain Cook's first trip around the world -- financed in large part by Sir Joseph Banks, who was also on the trip to collect plants) and brought Linnaeus specimens that fed his thirst for learning about and classifying plants.  In his life-time Linnaeus named and classified nearly 12,000 species, and in 1753 Linnaeus published his monumental botanical work, Species Plantarum which ordered, named, and described over 6,000 plants.  Species Plantarum is recognized as a turning point in botanical nomenclature as it firmly entrenched the binomial classification system and began bringing order to a chaotic botanical taxonomy.  Dozens of genera of plants in this "Southwest Colorado Wildflower" web site were first named and described in Species Plantarum.

Linnaeus wrote many other works in addition to Species Plantarum. One work which was quite dear to him was his 1737 Flora Lapponica following his 1732 six month collecting expedition to Lapland. There for the first time he saw what became his favorite plant, Linnaea borealis, named for him by his friend and fellow naturalist, Jan Frederik Gronovius.

Linnaeus jokingly tells us in his Critica Botanica, of Linnaea borealis being named for him, "It is commonly believed that the name of a plant which is derived from that of a botanist shows no connection between the two...[but]...Linnaea was named by the celebrated Gronovius and is a plant of Lapland, lowly, insignificant, disregarded, flowering but for a brief space -- after Linnaeus who resembles it."

And finally about scientific names:

We now assign plants to a division of life forms culminating in three basic levels: family (a large grouping of similar plants), genus (a family subdivision similar to a person’s last name which includes plants sharing a number of characteristics), and species (an even smaller division, similar to a person’s first name, in which each member has unique characteristics not shared by other members of that genus).  No two plants in the world have the same species name, that is, no two plants share the same binomial.

Scientific names are most often in Latin but Greek is quite common and names may be mixed: The genus, for instance, may be Greek and the species Latin.  By international agreement, though, we still say the "Latin name" even if part or all of the name is Greek.  One can avoid this humorous contradiction by saying "scientific name".

As indicated above, Linnaeus (and almost everyone prior to him and many following him) grouped plants almost exclusively on the basis of a single structural (morphological) characteristic.  William A. Weber, the authority on Colorado flora, states in his Colorado Flora, Western Slope 3rd edition (2001), that the criteria for grouping plants into distinct genera (and into families) should include the variety of diagnostic tools that modern botanists possess.  Further,  the grouping should not be based on "preconceptions" or "status quo".  Weber quotes Professor Reed Rollins: "Members of a genus must display a pattern of characters distinctive in itself and different from the pattern characteristic of any other genus."  The separation of plants into genera (and into families) may be "based not only on morphological data but [on] anatomical, cytological, genetic, and physiological data as well".

The naming of plants is an evolutionary process.  Dioscorides, Ray, Linnaeus, Bessya, Weber, and numerous others suggested new methods to bring order to the plant world.  Present and future botanists will suggest more refinements to establish families, genera, and species.  They will suggest new answers to many old questions: When there are plant synonyms, which name takes precedence?  Do past synonyms really describe the same plant?  That is, has anyone in the past inadvertently misidentified a plant?   What should be the bases for grouping plants?  That is, what genus or family does a plant really belong to?  Should families and genera be large and inclusive or should they be split apart to include only the most closely related plants?

There must be some standard at each moment in time so communication can proceed.  Scientific names in this web site are based on John Kartesz's Synthesis of the North American Flora and these names are always bold.  Synonyms found in William A. Weber and R. C. Wittmann's Colorado Flora, Western Slope, Welsh's A Utah Flora., Cronquist's Intermountain Flora, etc. are shown in non-bold type.

For details about the standardization of plant names see the on-line International Code of Botanical Nomenclature (2005).