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More Databases Linked & Search Improvements for Scientific Names

July 9th, 2024 by Alex Zorach

Since our last post about interlinking databases, we have interlinked four more databases, each of which is now shown in the external links at the bottom of each plant page. We also added a new feature for when you search by scientific name but no results are found. In this case we now run a second search of linked external records, which in many cases will return useful results.

This blog post first highlights the newly linked databases and then explains how the search improvements work.

Missouri Plants

We have already been interlinked with the Missouri Botanical Garden's (MOBOT's) Plant Finder for a long time, but Missouri Plants, unaffiliated with MOBOT, is something completely different. Whereas MOBOT focuses on horticultural cultivars and the use of plants in landscaping and gardening, Missouri Plants is, more like us, focused on plants in the wild.
screenshot of a website with black background and yellow text, with a photo of a bold red flower on green backgroundThis screenshot shows the page for fire pink (Silene virginica) on the Missouri Plants website. This page has a detailed botanical description accompanied by photos.

The website can be seen as an online continuation of the print book Flora of Missouri by George Yatskievych (1999) which was itself an update of the original Flora of Missouri by Julian Steyermark (1963).

On each page you will find photos, basic information on the plant's habitat in the state, and a botanical description, extensive on some pages, often accompanied by numerous illustrating pictures. The photography is outstanding for illustrating key identification features. The pages also note flowering periods, origin (native vs. introduced), and mention common lookalikes. The site makes an excellent addition to our linked resources and will be particularly useful for people in or near Missouri. Because of the emphasis on botanical descriptions and identification, we also display Missouri Plants pages in the list of references and links on our ID / Comparison guides.

Maryland Biodiversity Project

Maryland Biodiversity Project (MBP) is another exciting project that we have referenced before in our blog posts. We have been using it to construct range maps for a long time, but we only interlinked it recently. Although MBP covers other organisms besides plants, such as fungi and animals, we only link its plant pages. MBP is run by its own non-profit organization.
screenshot of a website showing closeup photos of plants on the left and a map of Maryland counties and links on the rightThis screenshot shows Maryland Biodiversity Project's page on slender three-seeded mercury (Acalypha gracilens). MBP's map for this species shows several counties beyond those reported in BONAP, which itself improved over the missing county-level data for MD in the USDA PLANTS database.

The most valuable materials to us on MBP's site are its county-level maps, which fill a key data gap. The USDA PLANTS database is missing county-level data for Maryland for most plants, and BONAP has only slightly improved on this major shortcoming. MBP however is quite comprehensive; although there are still limits to its data, we have found it to have the most accurate and comprehensive county-level data on plant distribution in Maryland. The site also shows a finer-level of plant distribution using grids smaller than most counties.

Besides distribution data, MBP also has high-resolution photographs on most pages. Some pages also have comments on taxonomy. There is a list of links but we emphasize that the links are auto-generated by scientific name, not manually-reviewed as we do for our external links.

Minnesota Wildflowers

Minnesota Wildflowers, unlike its name suggests, covers all sorts of plants that occur in the wild in Minnesota, even woody and non-flowering plants such as conifers. The website is run by a non-profit and, much like bplant.org, has an extraordinarily lean budget relative to the extent of the work it does.
screenshot of a website with a lot of sections, tables, links, and some small pictures of tree leaves and barkThis screenshot shows Minnesota Wildflower's page on Quercus alba (white oak). The existence of this page demonstrates that this website covers more than just wildflowers.

Each page features botanical descriptions, usually accompanied by photos. There is more emphasis on identification than on most sites, and there is typically an extensive verbal explanation of how to distinguish each species from other visually-similar species. As such, we also added this resource to the references and links on each ID / Comparison guide whenever there is a corresponding record on this site.

In addition to the description and identification tips, Minnesota Wildflowers has a brief description of habitat, wetland indicator status, and bloom season. It also has county-level distribution maps pinpointing specific locations within each county, reflecting herbarium records. These records are useful for us in building ecoregion range maps for many plants, like the white oak shown above, which meet their range limits in Minnesota.

Digital Atlas of the Virginia Flora

The Digital Atlas of the Virginia Flora, which can be referred to more concisely by its domain vaplantatlas.org, is our most recently-interlinked database. It is an outgrowth of the Flora of Virginia Project, which was published as a book from 1997 to 1992, and grew into an online Atlas of the Virginia Flora before the current iteration of the website.
screenshot of a webpage with a county map of Virginia, and some small plant photos on the right and a bit of text belowvaplantatlas.org's page on Geum vernum shows uncertainty about this plant's status as native vs. introduced. Our page on spring avens (Geum vernum) similarly denotes this uncertainty.

Like many regional databases, vaplantatlas.org features county-level maps, but one innovation that we particularly appreciate is that their maps also denote uncertainty. The rest of the page features photos and conveys other useful information in text, such as native status, scientific synonyms, and common names. The atlas also has separate records on subspecies or varieties.

What stands out the most to us about vaplantatlas.org is the depth of its habitat description for many taxa, often having a longer paragraph instead of just a brief sentence or phrase. Some records also have extensive comments on taxonomy, discussing reclassifications or other changes, identification issues, and other considerations. The combination of these two fields has made this site especially helpful in researching habitat and taxonomy alike.

Search Improvements

We face the ongoing problem that many plants have been reclassified, sometimes multiple times, and different authorities can refer to the same taxon by different scientific names. Synonymy (listing scientific synonyms) mostly addresses this issue as far as online search is concerned: a search for any listed synonyms will return a link to the taxon, and show the preferred name, which in most cases corresponds to the name used by POWO (Plants of the World Online.)

The problem is that the process of listing synonyms exhaustively is resource-intensive. In some cases, there is controversy of which synonyms to list, with different authorities using different classification schemes. Because taxonomy can be both confusing and controversial, we like to manually check each name instead of using an automated process to add them. So there are many synonyms which we have not yet listed. As such, when you type these names in, they may return no results in our search, even if they refer to a taxon which we already have listed on our site under another name.

To partly alleviate this shortcoming, we have added a new feature to our search. Now, whenever a scientific name returns no search results, we then run a search of unlinked records in all our interlinked dabatases and external websites. This query is carried out on our own database, not the websites themselves, so it represents a snapshot of the records on each website pulled at a certain time in the past, not a real-time search of the other websites. But in many cases, it will return records even when the same name does not return any results on our site.
screenshot of bplant.org showing a search returning No Plants Found but showing a list of external linksThis screenshot shows a search for the scientific name Dioscorea polystachya. Because our original plant list was pulled from the USDA PLANTS database, we pulled all errors in that dataset. One error was that the introduced plant properly called Dioscorea polystachya Turcz. was wrongly referred to as Dioscorea oppositifolia L., an error common in older sources. Although Dioscorea oppositifolia L. is an actual species, modern authorities agree that it is not found anywhere in North America. Before we resolved this issue, a search for the correct name "Dioscorea polystachya" on our site would return no results. However, with the new search feature, it returns a variety of records on external sites, helping to more quickly figure out what is going on. We have corrected the error, so the search now returns the proper page.

The fallback search returns a list of records on these external sites, which you can explore yourself. You may be able to figure out what taxon the name refers to, come back to our site and either type a widely-used common name into the search, or type in a scientific synonym to find our record. Furthermore, we have set up our system so that whenever anyone conducts a search that returns no records on our site, but returns external links, it notifies us by email that the taxon needs attention, so that we can research the taxon, add the unlinked synonyms, and then link up the unlinked records so that future searches will return the proper entry.

So not only are we improving the search experience for users, but we have created a system to facilitate us quickly resolving the synonymy for taxa for which there is demand for researching or reading about. We have already used this system to detect and resolve a number of inconsistencies, such as the misapplication of a scientific name for Chinese yam given in the above screenshot.

Stay Tuned for More Progress!

As with all of our linked databases, the main interlinking is not the end of the story. All four of these databases have a number (about 100-650 each) of unmatched records which reflect plants referred to by different scientific names and/or taxa that are treated differently in the different sources. It will take us considerable time to resolve them; we haven't even resolved all the records in some of the sources we linked over a year ago. However, we are continually making progress and you will continue seeing progress on all of these interlinking projects. And the good news is that we tend to resolve these by the plant, so when they are resolved for a particular plant, we fix the links for all external records at once, and set it up so future databases will link more seamlessly.

As always, you can support our work by donating, and also by sharing and linking to our site. If you run any of these websites or any website about plants, and want to interlink with us the way we have been linking to these databases, please get in touch because we would love to facilitate you doing so.

We also want to thank everyone who has continued supporting us, whether through donations or through talking about or sharing or linking to our site. We are over halfway through 2024 and this has proven to be a great year both in terms of what we've gotten done, and in terms of engagement on the site and support from our users. Thank you everyone!

And if you are looking for more projects to support, please consider donating to the organizations that run these websites, or any of the websites we link to. And certainly check them out, especially if you live in their areas of coverage!

Choosing The Best Common Names For Plants: Challenges & Solutions

April 19th, 2024 by Alex Zorach

Plants can be referred to either by common or scientific names. Scientific names, in theory, are less ambiguous. In practice though, there are limitations to scientific names too. Changes in or disagreement about taxonomy, combined with information propagating from older sources, can lead the same plant to be referred to by different scientific names. An example are the Joe Pyes (Eutrochium sp.) which are often still sold in nurseries as Eupatorium sp. in spite of being treated by most authorities as belonging to a separate genus for years now.

In other cases, the same name might refer to different groups of plants, such as when a species gets split into two or more species, an older source might use one name to refer to the entire population whereas newer sources might use that name only refer to a limited subset. An example is Phragmites australis, which some sources use to refer to both populations we consider to belong to the native American common reed (Phragmites americanus) and the introduced eurasian common reed (Phragmites australis), which were formerly considered to be subspecies of the same species. In this example, the common name "Eurasian common reed" is actually more ambiguous than saying Phragmites australis, because it is clear with the modifier "Eurasian" that you are referring only to the introduced Eurasian taxon, whereas with only the scientific name it is not clear whether you consider the native American taxon to be a subspecies of the same species, or a separate species.
orange and pale green, cup-shaped flowers with pale yellow flower parts, lobed, flat-tipped leaves, and dull gray branchesLiriodendron tulipifera is known by many names, including "American Tuliptree", "Tulip Poplar", "Yellow Poplar", "whitewood", and "fiddletree". Some of these names are better than others; Liriodendron is not closely related to most poplars (Populus), instead being closer-related to magnolias. More people in the population at large will know it by the names "tuliptree" or "yellow poplar" than by its scientific name Liriodendron tulipifera, which illustrates the importance of common names in material intended to reach a broad audience. Photo © skitterbug, CC BY 4.0, Source.

Common names can provide continuity through taxonomic changes, and also have the advantage of being in widespread use and more accessible. Names built from everyday words instead of in a separate scientific language is a major reason for their greater accessibility and common use. Both types of names are important, so on bplant.org we use both common and scientific names to refer to plants.

Because there are often multiple common names in use for a particular plant, we are often presented with the problem of choosing which name to use. Although we list all the widely-used common names we can find at the top of each article, and allow searching by each name, we still must pick a single common name to display wherever a particular species is mentioned on our site.

The casual nature of common names provides us flexibility. Scientific names are bound by rules governing which name is valid. If you agree on taxonomy, you can follow the rules and usually reach a consensus about which name to use for a particular species. With common names, because they are more arbitrary, you can simply choose which one to use. At bplant.org, we are opting to use that freedom to address some common naming problems, and communicate as much information as clearly as possible.

Problems With Some Common Names

There are numerous ways common names can be problematic. One of the worst things that can happen is if the name is ambiguous. For example, referring to a plant only as "hemlock" is problematic because it can refer to evergreen conifers of the Tsuga genus, but it can also refer to toxic carrot-family plants such as poison hemlock (Conium maculatum) or spotted water hemlock (Cicuta maculata). In some cases, even names contaning modifiers can be ambiguous; for example, "Spanish oak" can refer to southern red oak (Quercus falcata), Texas red oak (Quercus buckleyi), or to Quercus ×hispanica, a hybrid of European turkey oak (Quercus cerris) and cork oak (Quercus suber), both of which are introduced plants in North America. Such examples are widespread and we do our best to avoid such ambiguity, and notate it in the "Notes" field of each article when it does occur.
lacy white flowerhead with many tiny flowers, more unopened flowerheads behind, and finely-cut leavesThis photo shows poison hemlock (Conium maculatum), which bears little resemblance to the evergreen trees bearing the same common name, belonging to the Tsuga genus. Photo © P Holroyd, CC BY 4.0, Source.

Another problem is that certain plant names can be offensive, such as by containing racial slurs. These names, thankfully, are getting phased out, and we also are doing our best to avoid offensive names.

Slightly more subtle problems include plants where the descriptor is misleading. For example, Japanese creeper (Parthenocissus tricuspidata) is often referred to in the US as "Boston Ivy" which is misleading as it is not native to Boston. Another example that is less-well-known but perhaps more-misleading is Savoy hawkweed (Hieracium sabaudum), which is frequently referred to as "New England hawkweed". This name is misleading as it is not native to New England, nor is it particularly widespread in New England, absent from 3 states and only reported in isolated counties of the others, whereas many other hawkweeds, such as rough hawkweed (Hieracium scabrum), are not only native but widespread and found in virtually all parts of New England.

Sometimes the misleading aspects of the name refer to the plant's physical characteristics. For example, black-fruited clearweed (Pilea fontana) is sometimes referred to as "lesser clearweed", but the species of clearweed (Pilea) that it most overlaps with is Canadian clearweed (Pilea pumila), and the sizes of these two species are both variable with nearly-full overlap, so the name wrongly leads people to expect that P. fontana is smaller. Another example involving morphology appears in sweet wood reed (Cinna arundinacea), which is sometimes referred to as "stout wood reed". This grass is not particularly stout; its stems are slender relative to a number of other grasses of similar height, its blades are narrower than many related grasses, and it also tends to have a tall and narrow form, certainly not the most "stout" growth habit even compared to other grasses that occur together with it in the same habitat.
a plant with opposite, serrated leaves and fine black seed clusters in the leaf axils, against a weedy backgroundThis photo, showing visibly dark fruit, illustrates why we think "black-fruited clearweed" is a better common name than "lesser clearweed". Photo © Ryan Sorrells, CC BY 4.0, Source.

These examples guide us towards a set of criteria for choosing the best common names. In some cases, the descriptiveness of a less-commonly-used name is so superior that we have decided it is worth favoring it in the interest of education and clarity.

What makes a good common name?

The best common names tend to fit the following patterns:
  • They are unambiguous, used only to refer only to one species and not others.
  • They are already widely in use.
  • Their full names communicate categorical relationships, such as membership in a particular genus or other taxon.
  • They coincide with or directly relate to the scientific name, such as being a direct translation of the Latin.
  • They are inoffensive.
  • They accurately describe the plant's native range.
  • They accurately describe some prominent physical characteristic of the plant.
  • They accurately describe of the plant's habitat.
Most names do some of these things together. For example, "swamp white oak" communicates three layers of taxonomy: oak refers to the Quercus genus, "white oak" to the white oak section within that genus, and "swamp white oak" completely specifies the species Quercus bicolor. Furthermore, the term "swamp" accurately communicates that this species tends to grow in wetter habitats than other oaks; it is one of the bottomland oaks, usually found on moist sites with poor drainage. On top of these things "white oak" also references the lighter color of the wood, and often bark, of that class of oaks relative to red oaks, the other major grouping in North America.
shallowly-lobed leaves, green, turning yellow and brown, tree trunks, leaf litter on the ground, and water in the backgroundSwamp white oak is an example of what we consider a good common name, unambiguous while accurately communicating two layers of taxonomy as well as its preference for low, wet habitats. Here one grows at Laplatte River Marsh Natural Area in Shelburne, VT. Photo © Tom Scavo, CC BY 4.0, Source.

Another such example is "Limber pine dwarf mistletoe", which communicates not only membership in the Arceuthobium genus (Dwarf mistletoes), but that this is a specific species, (Arceuthobium cyanocarpum) and that limber pine (Pinus flexilis) is one of its hosts.

Sometimes we pick name because it is "less bad".

There are, unfortunately, a lot of cases where it is not possible to pick a name that ticks even most of the more important boxes discussed above. For example, we stuck with the name Robin's plantain (Erigeron pulchellus) even though it is slightly misleading and the descriptor "Robin's" isn't particularly informative. Erigeron pulchellus is not a plantain (Plantago sp.), although its rosette of basal leaves pressed tightly against the ground is slightly evocative of that genus. We stuck with that name not only because it is by far the most widely-used, but also because the only other names are ambiguous or even more misleading. For example, it is sometimes called "hairy plantain" but that more often refers to hairy fleabane (Erigeron pubescens). And it is sometimes called "blue spring daisy" but it does not belong to the daisy (Bellis) genus nor even the Bellidinae tribe, and its flowers are not particularly blue, usually at closest a bluish purple or lavender, not even the bluest of the Erigeron genus, a title that in Eastern North America would go to oakleaf fleabane (Erigeron quercifolius).
daisy-like flower, white with yellow center, on a stalk from a rosette of leaves growing on a slope with exposed poor soilRobin's plantain has a slightly unfortunate name, although not totally without merit, as its basal leaves slightly resemble the "plantains" of the Plantago genus. Photo © mjpapay, CC BY 4.0, Source.

Another unfortunate example is Maryland sanicle (Sanicula marilandica) which is also called Maryland bleck snakeroot. Although the "Maryland" descriptor coincides with the scientific epithet marilandica, it is misleading. This primarily northern species is more common and widespread from New England through the Upper Midwest and well into Canada; although native to Maryland, it only occurs in isolated locations throughout the state, and with global warming has become increasingly rare in much of its range there. It is not and was never the most common or widespread sanicle (Sanicula) in the state; that title goes to Canadian blacksnakeroot (Sanicula canadensis), which, also contrary to its scientific and common names, is the more southerly of the two species.

Sometimes a careful choice can fix these confusing scenarios. For example, another pairing with misleading common names is narrow-leaved spring beauty (Claytonia virginica) and northern spring beauty (Claytonia caroliniana), which are often referred to, respectively, as "Virginia" and "Carolina" spring beauties, in correspondence with their scientific names. As with the two sanicles above, the ranges of these species are reversed from what the names would suggest. Although "Carolina spring beauty" is native to the Carolinas, it is only native to high elevations in the mountains in their most inland portions. Of the two species it is definitively the more northerly of the species, preferring northern hardwood forests that grow in cooler climates. The name "northern spring beauty" is thus much more descriptive than "Carolina", especially relative to "Virginia spring beauty", since the Carolinas are farther south than Virginia. In this case, we were able to make a better choice because the common names "narrow-leaved spring beauty" and "northern spring beauty" were already in use. But these names might still be slightly "bad" to some people in that they may be less familiar, and they do not correspond to the scientific epithets.
a plant with narrow leaves and two white-and-pink 5-petaled flowers, poking up through leaf litterWe favor the name narrow-leaved spring beauty (Claytonia virginica) for this plant, as it is more descriptive of the plant's morphology and avoids the misleading implication of range relative to northern spring beauty (Claytonia caroliniana) if using the terms "Virginia" vs. "Carolina". Photo © Jonathan Sowers, CC BY 4.0, Source.

Progress at Updating Common Names

As you can see from the examples above, updating common names requires research and balancing of multiple aspects, including common usage, range, ecology, and morphology, among other considerations. So it can be a slow process. But we think it is important as it serves the goal of making our material as accessible and educational as possible.

Nearly all (all but 37) of the plants listed on our site have at least one common name listed; in most cases, we defaulted to the common names used by the USDA PLANTS database, but over time, we plan on reviewing all common names. Where multiple common names are in use, we have found that the a large portion of the USDA PLANTS common names differ from the choices we would ideally make, and we have been updating our names as we review records. The USDA names more often coincide more closely with scientific names, which is only one of many criteria we use and not the one we give the highest priority.

We have currently added alternate common names to 708 plants, and of these, we have chosen common names to avoid misleading names in at least 47 cases and resolve ambiguity in at least 24 cases. As with all our work, the checking of common names is an ongoing process.

As always, we appreciate everyone who has donated to support our site. Donations help fund the work described here, as well as all the other work we have been doing recently, including building and refining range maps, completing new ID Guides and ecoregion and plant articles, and maintaining the site's servers and software to keep it up and running and loading quickly. Although we have received substantial funding we still are far from our funding goals and remain a mostly-volunteer effort. The long-term goal is to fund a larger team of people to work full-time on the site, but for now we are still working to get a sustainable annual budget to support my work on the site. Thank you to everone who has contributed!

Range Map & Taxonomic Update Progress

January 31st, 2024 by Alex Zorach

Back in September of 2022 we announced that we had completely retired our first-generation range maps, replacing them with new and improved maps. However, many aspects of our maps remained incomplete. Many species still lacked maps, and most maps were strictly limited to the lower 48 US states, not extending into Canada, Alaska, or Mexico.

We have since made great strides in map completion:
  • 16838 plants now have range maps. This is over 81.5% of the plants listed on our site.
  • 5061 maps have been completed for all of North America, including Canada, Alaska, and Mexico for species that occur there. This is now over 30% of our published maps.
  • 5653 plants (over 27% of plants) have been interlinked with Plants of the World Online (POWO) and had their taxonomy updated to reflect the information from POWO.
  • We began marking plants that we wanted to list on our site, but that do not occur in the wild in North America and thus have no map or an empty map. We currently list 27 such plants and this number will probably increase quickly now that we have this category.
What is perhaps most exciting, however, is not reflected in the numbers alone: we have developed techniques and frameworks for building range maps outside the lower 48 states. This means it is just a matter of time and hard work before the remaining maps are completed.

Why has the rate of map completion slowed down?

If you have been following us since the beginning, you will notice that our rate of completion of range maps has slowed down considerably. We have been putting more time and effort into range maps recently though. The slowdown is both because we completed the easier maps first, and because we are developing higher standards as we further refine existing maps.
box turtle with a dark brown shell with orange accents, walking over leaf litterLike this Eastern Box Turtle (Terrapene carolina ssp. carolina), we are getting to our destination slowly. The featured plant is Virginia creeper (Parthenocissus quinquefolia). Photo © Jay Brasher, CC BY 4.0, Source.

In many cases, constructing maps was straightforward because there was complete, accurate data available from the various sources we consult, and the different authorities agreed on plant ranges and establishment means (i.e. native vs. introduced.)

In other cases, things get messy. Sometimes data is missing or incomplete. Often, different sources disagree, and we need to research and make tough judgment calls about which material to accept as correct. Common issues include misidentifications, and different standards in different sources about when to consider a record a cultivated plant, vs. a waif (a transient introduction into the wild that does not persist), vs. solidly established in the wild. Many plants also have taxonomic complexities, such as splits, merges, and other reclassifications. Taxonomy can also interact with identification issues, such as when a record was identified as a particular variety or subspecies, but that taxon then later up getting moved into another species.

We have been building our range maps by conducting multiple sweeps through the data. On each sweep, we construct maps using the tools and processes we have available, and put a certain portion of the remaining map in a "messy" bin, to do later. At the same time, we also work to improve and streamline our map building process. Over time, the plants left in the "messy" bin become progressively more difficult to deal with, so even with better tools to facilitate our work, our maps become slower to build with each pass.
Not Present
Native or Not Present
Native or Expanded
Expanded or Not Present

The map for slender snakecotton (Froelichia gracilis) illustrates multiple challenges and complexities. Its native range extends into Mexico, in ecoregions that do not intersect the United States. Although native to North America, it is now found in areas beyond its native range, but it has also been extirpated from part of its native range. Some of the new parts of its range are adjacent to the native range (and thus we mark them Expanded) whereas the California populations are separated by long distances and major geographic divides (and thus we mark it Introduced.) Different sources also disagree as to exactly where it is native; in this case we took BONAP's report over POWO's. And all of this has happened without any taxonomic complexity; this map, believe it or not, was relatively easier to build than many of the ones we have completed recently.

Our standards are also higher with our second-generation range maps; early on we just wanted to get something out, whereas now we have more different categories on the map legend and are taking care to notate uncertainty in the map itself. Related to these high standards, if you see something that you think is inaccurate or could be improved, please contact us. You do not need to be an expert to help us refine our maps. Seeing a species in the wild outside its reported range, or just seeing something on a map that you think doesn't make sense, are both signs that you may have something to contribute.

Interlinking with Plants of The World Online (POWO)

POWO is a taxonomic backbone run by the Kew Botanical Garden in London. In contrast to our routine, mostly-automated interlinking with other databases, our interlinking with POWO involves examining POWO's treatment of each taxon and comparing it to the schemes used by other authorities. Records integrated with POWO have mostly been brought up-to-date with modern taxonomic changes. In the overwhelming majority of cases, we adopt POWO's treatment. In the few cases where we adopt a different treatment (this usually happens in the rare cases where POWO is not up-to-date on newer work and another source we consult is), we still carefully examine POWO's listing. In a few cases we have enacted splits that POWO has not, in line with Flora of the Southeastern U.S. (FSUS) by Alan Weakley.

Differences in classification are a primary reason for discrepancies in plant range maps between different sources. There is often not a 1-to-1 relationship between records. You can read about how we resolved these discrepancies in the notes fields on each plant page. Taxonomy notes are located above the table-of-contents, right under the plant's names. This placement ensures people will have a clearer idea of what taxon the page refers to before reading the article or seeing the map, in the case that there have been confusing reclassifications or inconsistencies in naming. The range map notes are found directly under the map, and explain any judgment calls we made in constructing the map as well as any clarifying info beyond that conveyed by the legend.
grape-like vine with pale green, magenta, and cyan fruit, on a chain-link fencePorcelain berry (Ampelopsis glandulosa), an invasive vine in the Mid-Atlantic to Northeast, has taxonomy notes explaining its reclassification from a proper species into a variety of another species. Photo © Ron Burkert, CC BY 4.0, Source.

Although the notes are brief on most articles, and many articles lack notes entirely, the total extent of notes is massive. We have already published over 16,000 words in the taxonomy notes, and over 58,000 words in the range map notes. This amounts to about 250 full pages of text. These counts do not include automatically-generated legends nd other verbal notes listed under many maps. The volume of these notes explains why our progress on the more difficult plants is progressing more slowly. We want to make sure we both document and explain our choices, especially in the cases where different sources disagree on taxonomy or ranges.

No Maps: Plants Not Occurring in The Wild in North America

Although we focus on plants occuring in the wild in North America, we list a number of plants with empty range maps, meaning that these species are not and have never been found in the wild here. These plants broadly fit into one of two categories: plants that are widely cultivated, but have never established or been recorded in the wild, or plants that were reported somewhere in the wild but where those records were later deemed to be invalid. We retain both of these types of records for several reasons.

For garden and landscaping plants not recorded establishing in the wild, it is always possible that these plants will establish in the wild at some point in the future. Being aware of these plants and knowing how to identify them can ensure they are more quickly detected if they ever do escape and naturalize.

Some plants were widely planted for years or even decades without naturalizing, only to eventually escape into the wild, sometimes even becoming invasive. For example, kudzu (Pueraria montana) was brought to the US in 1876, but the first herbarium specimen we could find, collected from the wild in North America, was from 1901, and kudzu was not recognized as invasive until decades after that.
giant vines completely engulfing a roadside landscapeKudzu (Pueraria montana) is so invasive in the southeastern US that it is often described as "the vine that ate the south", but it was planted for decades before it was first observed in the wild, and many more decades before it became invasive. The case of kudzu illustrates the importance of monitoring introduced cultivated plants even when they have not been recorded escaping into the wild. Photo © Siddarth Machado, CC BY 4.0, Source.

It is also possible that plants are already present in the wild in North America, but that people have not reported them because they are hard to identify and/or they do not know that they need to check against them. For eaxmple, we have found Japanese honewort (Cryptotaenia japonica) in the wild in two ecoregions, in Delaware and Pennsylvania, and that species is not reported occurring in the wild by BONAP or POWO. Excepting the purple-leaf cultivar, that species may be underreported because it is visually similar to the native honewort (Cryptotaenia canadensis).
a plant with sets of three purplish-bronze leaflets with serrated margins, purple-brown stems, and tiny pale pink flowersJapanese honewort (Cryptotaenia japonica) is one plant that has escaped cultivation and established in the wild in a few parks across the US, and may have invasive potential, but is not yet listed by any major authorities. We list this plant, but there are likely many more such plants where we have not yet learned of their establishment. Photo © Zihao Wang, CC BY 4.0, Source.

A completely different scenario is when older sources report a particular plant somewhere in North America, but the record has been deemed invalid. In these cases, we retain a record specifically because there is other information out there that needs to be corrected. Even when the original source has been updated to correct the record, it is common, especially with sites like USDA PLANTS, that numerous other websites and print sources repeated the inaccurate information before it was corrected, and these other sources are often not corrected. Sometimes misinformation can propagate in secondary sources for decades after the original source corrected it because no one goes back to check the primary source. In the plant world, this phenomenon is especially prevalent in sources relating to horticulture, gardening, and the commercial nursery industry, where the standards of scholarship are much lower than in the sort of scientific sources we rely on.

Examples of such plants include mountain soursop (Annona montana), Syrian cephalaria (Cephalaria syriaca), braceletwood (Jacquinia armillaris), and willowleaf frostweed (Helianthemum salicifolium). We have noticed such errors are especially common in south Florida where there is a huge volume of introduced tropcial species that cannot survive in most of the rest of the continental US.

The First Range Maps and Lists for Canada and Mexico Finer-Tuned Than Provinces/States

One thing that has frustrated me for years is the lack of fine-tuned range maps and plant lists for regions outside the US, particularly, for Canada and Mexico. Apart from specific sources such as the Silvics of North America, which only covers about 200 tree species, and some print field guides, which similarly do not exhaustively cover the plants of North America, there are no sources with range data as fine-tuned as that presented by BONAP and USDA Plants.

Although Canada and Mexico both have administrative divisions finer than States and Provinces, there is no equivalent of USDA PLANTS and BONAP for these countries. Canadensys, the closest to a Canadian analogue of these sources, only has data at the level of individual provinces, and the existence of finer-tuned regional data, when it is available at all, is spotty and not accessible in a single place. In Mexico, there is no such website at all.

Although the lack of data has made it much harder for us to build range maps in Canada and Mexico, it also makes our maps much more valuable and groundbreaking in the cases in which we have been able to build them. In these cases, our maps offer a finer level of detail than anything else out there.
vine with dangling, yellow, lantern-like blossoms, and clusters of many seeds with long, curved, wispy attachmentsGolden clematis (Clematis tangutica), also called orange-peel clematis has become invasive in Canada, but has not established in the wild in the lower 48 United States. Photo © MandarinDuck008, CC BY 4.0, Source.

Clematis tangutica is one of many species whose range in North America is restricted to Canada and Alaska; in the two ecoregions that cross the border, it is only known to occur north of the border.

The process of constructing these maps is slow and also error-prone. In many cases, it involves examining individual herbarium records. Although there are good tools (the most important of which is GBIF, the Global Biodiversity Information Facility), there are numerous limitations of the data available. Some herbarium specimens have yet to be digitized, thus making it hard to assess the completeness of some range maps (i.e. it being harder to conclude that a species does not occur somewhere, relative to knowing that it does occur somewhere.) Where records exist, many records have geolocation errors, and in many cases there is insufficient verbal description of the location to catch such errors. Even when the locations are accurate, other aspects of the records can be erroneous, such as plants reported as wild that were actually cultivated, or specimens that were misidentified. And on top of this, we have all the same reclassification issues discussed above, but they are uglier because different herbaria (and even different individuals) may follow different schemes, and reclassifications can thus play out differently from one record to the next.

The process of building these maps thus involves delving into individual herbarium records in a way that rarely is necessary when constructing maps for the lower 48 US. As such, it is much slower. However the results can be rewarding.

As we complete these maps, we move towards plant lists for ecoregions outside the continental US. Back when we launced ecoregion-based plant lists in March of 2022, a major deficiency of our lists was that we had no lists for Canada, Alaska, and Mexico. Although we have not completed them, we are seeing the beginnings of these lists for all three of these regions, and it's just a matter of time before they are complete enough that we can publish tentative lists. Our work is also improving the accuracy and completeness of the plant lists for ecoregions that are split between the lower 48 US and either Canada or Mexico, and there are many such regions. Canada and Alaska will likely be completed long before Mexico, both because there is much less plant biodiversity in the Arctic and more in the Tropics, and also because there are more sources available for Canada and Alaska, and lastly because there is less of a language barrier.

Moving Forward: Things To Come

You can expect a continued focus on range map completion over the next few months. We are still in a phase where we are getting a lot done and we hope to keep improving our tools and techniques so that we don't end up getting completely stuck on the difficult maps. So far, so good!

I also want to thank everyone too for ongoing financial support that has allowed me to keep working on this project. Although we still have not met our next financial goal of $20,000, we are getting a lot closer to it. The vision of expanding into a larger organization with staff may remain far off, but for now we are able to keep the site going and keep it ad-free for the forseeable future. I have not yet published the year-end finances but this is another thing to expect in the next several weeks.

Archive of All Blogs

More Databases Linked & Search Improvements for Scientific Names, July 9th, 2024

Choosing The Best Common Names For Plants: Challenges & Solutions, April 19th, 2024

Range Map & Taxonomic Update Progress, January 31st, 2024

Giving Thanks To Everyone We Rely On, November 22nd, 2023

Thinking More Deeply About Habitat, April 5th, 2023

2022 Year-End Summary: Successes & New Goals, February 15th, 2023

New Databases Linked: Flora of North America & NatureServe Explorer, November 11th, 2022

All Range Maps 2nd Generation, Taxonomic Updates, & Fundraising Goal Met!, September 29th, 2022

More Range Map Improvements, POWO Interlinking, And Notes Fields, June 7th, 2022

Ecoregion-Based Plant Lists and Search, March 30th, 2022

Progress Updates on Range Maps and More, February 10th, 2022

The Vision for bplant.org, December 9th, 2021

New Server: Software & Hardware, August 30th, 2021

More & Improved Plant Range Maps, July 19th, 2021

A Control Section for Invasive Plants, April 15th, 2021

Progress Bars & State Ecoregion Legends, March 11th, 2021

Our 2020 Achievements, February 9th, 2021

Interlinking Databases for Plant Research, November 11th, 2020

A New Homepage, Highlighting Our Articles, July 29th, 2020

A False Recovery, But North Carolina's Ecoregions are Complete!, June 9th, 2020

We're Back After COVID-19 Setbacks, April 3rd, 2020

Help Us Find Ecoregion Photos, February 27th, 2020

What We Achieved in 2019, December 30th, 2019

Plant Comparison and ID Guides, October 30th, 2019

We Are Now Accepting Donations, October 14th, 2019

US State Ecoregion Maps, New Footer, Ecoregion Article Progress, and References, September 19th, 2019

Tentative Range Maps of Native Plants, August 12th, 2019

Ecoregion Locator and Interactive Maps, July 10th, 2019

Using Ecoregions Over Political Boundaries, May 13th, 2019

How We Handle Wild vs Cultivated Plants, April 16th, 2019

A Blog To Keep People Updated On Our Progress, April 8th, 2019

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