2024 Edition • Donate • Get the App • Cite this Page
X

Colors

Data mode

Account

Login
Sign up

Support FSUS...

We've finished our 2024 fundraiser. Many thanks to those who have given! It's not too late to support us (click here)...

A NOTE TO USERS OF THE 2024 EDITION of the FLORA OF THE SOUTHEASTERN UNITED STATES

Table of Contents

Flora formats
Flora goals
Recent changes: taxa and area
Graphic Key (FloraQuest App)
A final note
Citing the Flora
PREFACE
Sources of information.
Criteria for inclusion of taxa
Detailed dichotomous keys
The species account
Distribution Maps
Literature
Conservation Information
Comments
Wetland Indicator Status
Heliophily
ACKNOWLEDGMENTS
THE “BIG KEY”: KEY TO FAMILIES (AND IN MANY CASES GENERA), AND GENERAL ADVICE ON USING A DICHOTOMOUS KEY
Characteristics of major groups of vascular plants.

I started this project about 35 years ago, initially as a means of providing Natural Heritage biodiversity explorers in North Carolina with the most effective keys possible (and with an emphasis on vegetative features) to the set of species recognized most currently. Since that time, we have expanded the geographic boundaries of the Flora’s coverage to meet the needs of effective biodiversity inventory and science in other parts of the southeastern United States. This geographic expansion, first to Virginia, then to Georgia, then led to the 2015 Flora region: southeast of the Mississippi River, Ohio River and Mason-Dixon Line but excluding peninsular Florida. Having gone so far, it then made sense that the Flora embrace the biogeographic region of the moist, relictual, unglaciated southeastern North America: south of the glacial boundary and east of the “dry line” to the west that marks a marked floristic boundary to the Great Plains prairies to the northwest and the Madrean woodlands and scrub to the southwest. We differ with Takhtajan (1986: Floristic Regions of the World); however, by regarding the parts of southeastern North America inland in the “hard rock provinces” but south of the glacial boundary as being fundamentally “southeastern”, connected to the Coastal Plain, and retaining the core diversity of the critical temperate Eastern North American relictual flora, badly needing coverage in a modern treatment. We have also rounded off (actually “straightened off”) the Flora boundary to include the glaciated portions of two states that are primarily unglaciated, Pennsylvania and New Jersey, to provide comprehensive coverage for state-based usage in those states.

↑ Back to top of page

Flora formats

In 2023, we retained the Flora in PDF format as well as added two significant new formats, with all three together representing the Flora. The two new formats are FloraQuest, a set of mobile apps for both Apple iOS and Google platform devices, and the Flora of the Southeastern US web app available at https://fsus.ncbg.unc.edu. In March 2024, we released FloraQuest: Carolinas and Georgia, and upgraded FloraQuest: Northern Tier (see figure 2 of ranges of all FloraQuest apps). We also released state and regional PDFs, and upgraded the web app with wetland statuses, G-ranks, and Heliophily ranks, and revised keys, diagnostic photographs, text, and other assorted flora information. There are advantages and disadvantages to each format which we will clarify in the near future.

↑ Back to top of page

Flora goals

Some of the goals and principles underlying the Flora have always been and remain:

  1. It should be a catalog of the species in the region as modern and accurate as possible and based on modern species concepts.
  2. It should be a basic resource focused on biodiversity exploration and inventory, including the discovery of populations of rare species, and the accurate reporting of species from ecological plots and site inventory lists. This to me implies keys based as much as possible on plant characteristics readily observable (especially vegetative characteristics) throughout the growing season.
  3. It should have broad geographic coverage to promote discoveries of range extensions in the still-very-imperfectly-explored southeastern United States.
  4. It should provide detailed information on the habitats of species, in order to emphasize the ecological context of our flora and a habitat-based perspective on its exploration and conservation.
  5. The keys should be structured non-traditionally and pragmatically to juxtapose species or groups superficially similar and easily mistakable (e.g., Hydrastis, Podophyllum, and Diphylleia should be keyed near one another, as should Nyssa and Diospyros, and Polygonatum, Smilacina, Uvularia, Prosartes, and Streptopus). Identification notes should call attention to similar and mistakable taxa, even if they are not taxonomically close. Keys should NOT be written “by those who don’t need them, for those who won’t be able to use them”.
  6. Biogeographical understanding should be facilitated, by making clear the distributions of species within the region and beyond, and the nativity status should be immediately clear (including uncertainty about nativity). The “little maps” provided for each species have been designed to graphically provide the most concentrated biogeographic information possible in a very small space.
  7. The advantages of a geographically narrowly focused flora and a geographically broader flora can be largely combined with digital tools and subsets -- which we are innovating and have begun to make available in “derivative floras” and apps.
  8. The Flora should not be dry, academic, and devoid of life, but should reflect the immense wonder of the subject – while also being scientifically rigorous, exhaustively researched, and referenced in ways to facilitate the interested user’s additional exploration in the scientific literature.
  9. Waifs and minimally naturalized aliens that have likelihood of moving into natural areas in the near future should be included as an “early warning system” and because such species still “need to be identified” and their naturalization status is often not obvious when encountered in the field or herbarium.
  10. It should be open source, open access, and developed collaboratively from all information available.

Put another way – I’m trying to create the Flora I’ve always wished I had had!

↑ Back to top of page

Recent changes: taxa and area

The number of species (and other unique “finest level taxa”, e.g. varieties and subspecies when a species has more than one in the Flora region) has increased from about 7,500 in 2015 to 10,046 in 2020, to 10,719 in the 2022 edition, to 10,795 in the 2023 edition, to 10,837 in the 2024 edition. This increase was initially a reflection of geographic expansions in the flora (“scope-creep”), and more recently reflects taxa new to science as well as new discoveries of waifs, non-natives, or natives discovered in the flora region.

Areas added to the Flora in the 2022 Edition included:

  1. Pennsylvania, New Jersey, and New York (southern Long Island). These areas are primarily unglaciated (or were formed as sandy, terminal moraine outwash plains) and clearly have an “unglaciated warm temperate interior Southeast” flora in their interior (“hard rock”) provinces, and a Southeastern Coastal Plain floristic component-- the Coastal Plain flora strongly developed in s. New Jersey and s. Long Island (Pine Barrens), but only barely present in Pennsylvania (a narrow fringe along the Delaware River, now mainly urbanized). Central and southern Pennsylvania represents the north range extend for many Southern Appalachian and Southern/Central Appalachian endemics, and the Pine Barrens are likewise the northern range edge of many Southeastern Coastal Plain species and includes a flora with endemics with southern sister species. “Rounding off” the northern Flora boundary by including glaciated northwestern New Jersey, northeastern Pennsylvania, and northwestern Pennsylvania does add (less than a hundred) species more characteristic of the glaciated northeastern United States and Canada, but has the pragmatic advantage of making the Flora useful for state-based users in Pennsylvania, New Jersey, and southern New York.
  2. The “southern Midwest” of unglaciated southern Illinois, southern Indiana, and southern Ohio. The unglaciated portions of these states “face south” -- are floristically similar to areas just to the south across the Ohio River (Kentucky, West Virginia) and Mississippi River (southeastern Missouri). Their inclusion is straightforward and adds few taxa; in contrast, glaciated portions of these states have several hundred additional species (especially wetland and northern prairie species), and the Great Lakes shores of these states would add more – so I have not “gone there”.
  3. “Trans-Mississippian Southeast”, the part of the Southeast west of the Mississippi River:
    1. The Interior Highlands of Arkansas, southern Missouri, and Oklahoma. Floristically, the Ozarks and Ouachitas are part of the core “unglaciated warm temperate interior Southeast” and share most of their flora with the other upland provinces than can be so described. The Ozarks and Ouachitas also have profound relationships with the Appalachians and Interior Low Plateau eastwards, high endemism, and have not been well-covered in a modern Flora.
    2. The western half of the Mississippi River Alluvial Plain. This is very similar to the eastern side of the River and adds few species not already included in the Flora – though some in areas like the Grand Prairie of Arkansas and the Mississippi River delta of Louisiana.
    3. The narrowly-defined West Gulf Coastal Plain of primarily western Louisiana and eastern (“Pineywoods”) Texas (but including portions of southern Arkansas and southeastern Oklahoma). The West Gulf Coastal Plain is an intrinsic part of the core southeastern Coastal Plain, in part characterized by the longleaf pine ecosystem. Many genera and species of that ecosystem are disjunct west of the River, but there is also substantial endemism, in an area poorly served by modern floras.
    4. The remainder of the North American Coastal Plain in Texas and Oklahoma and adjacent areas (ecoregions often referred to as Gulf Prairies and Marshes, Post Oak Savanna, Blackland Prairies, and Cross Timbers). These areas admittedly represent a transition in the northern part of the region (Oklahoma and northeastern Texas) to Plainsian ecosystems and further south to Tamaulipan and Madrean ecosystems, but retain a predominantly southeastern floristic affinity and many species (including endemics) of southeastern genera. The 2022 edition includes the entirety of the Cross Timbers ecoregion (Fig. 1), which includes portions of TX, OK, and KS. The Cross Timbers region, while marking the vegetational boundary between the southwest arid zones and Great Plains to the west and the eastern deciduous forests to the east, still contains a strong overlap with the flora of the Southeast.
  4. Peninsular Florida. Most of peninsular Florida, its plant species and its ecosystems are clearly part of the core Southeastern Coastal Plain. Even the coastal fringes of the central peninsula and the breadth of the southern peninsula, though, have a predominantly Southeastern North American flora (including dominant species, like Taxodium ascendens, Quercus virginiana, etc., missing from the West Indies) with an increasing admixture of tropical and subtropical components of West Indian affinity or broader Caribbean affinity, and a few more generally neotropical or pantropical taxa. And while the Monroe County keys have a more strongly West Indian / Caribbean flora, their overall flora has a very strong overlap with mainland Florida and it would make little sense to orphan them from a “Southeastern Flora”.

Figure 1. Map of the region covered by the Flora, from 2022 onward. Full state lines provided for context, white background areas not included in the flora.

Figure 2. Map of the regions covered by the FloraQuest apps.

Figure 3. Map of the Flora Region as it has evolved over time

 

What does all this mean for users of the 2024 Edition?

The process of fully adding several thousand species, several hundred genera, and several tens of families to the Flora remains incomplete, though we have made substantial progress on this in the past year. We have prioritized to a degree by various factors: taxonomic level (working generally from finest upwards), geography (northern fringe of NJ, PA, OH, IN, IL, nontropical FL peninsula, and LA, AR, and MO first, leaving southernmost FL, and OK and TX for later), nativity (natives first, as more important for biodiversity conservation work), and abundance (more common species first). Genera and families around the periphery of the Southeast (especially western areas of OK and TX and tropical Florida) have been “worked over” less intensely, with less reassessment of taxonomic decisions, less use (so far) and citation of literature, and some keys are entirely absent, incomplete, or simply less perfect than we would wish them.

In the print/PDF version of the Flora, for each genus key, taxa that are not keyed are shown under “Unkeyed taxa: XX” (for non-waif taxa that have not yet been included in the key) and “Unkeyed waifs: YY” (for waifs that have not yet been included in the key). As of March 2024, 263 genera have one or more non-waif species unkeyed, mostly taxa occurring only in the OK, TX, or southern FL portions of the Flora region. 407 genera have one or more waif species unkeyed, also mostly in the OK, TX, and southern FL regions. When keying a plant, be sure to note if there are “unkeyed” taxa listed for that genus. For those taxa not keyed, you may be able to deduce the identity of your plant by checking the range maps for each taxon as it is plausible that those taxa may not occur within your region (i.e., the key may very likely be complete for your location, even though it is not fully complete for the entire flora region). We are working diligently to complete these keys, among many other priorities.

There is no equivalent indication for genera that have not been included in the family’s key to genera, or for genera or families that have not been included (or not fully and completely included) in the “Big Key” – what is in most floras a key to families, but in this Flora is pragmatically a key to families or in many cases genera that best key distinctively and practically at that level of key.

↑ Back to top of page

Graphic Key (FloraQuest App)

Users of the FloraQuest mobile apps have an additional feature worth introducing here: the graphic key. To use this key, the app will ask a series of questions. Answering these questions will reduce the nearly 11,000+ vascular plant taxa in the Southeastern U.S. to a smaller, prioritized list of plants that will include the plant that is being observed. How does this work? First the device will determine your location to put you in a given state and physiographic region (for example, the mountains of South Carolina or the piedmont of New Jersey, etc.), reducing the number of potential taxa from 10,000+ to a few thousand. Then you answer a series of relatively simple questions on the plant’s habitat (e.g., sunny location, wet location), phenology (e.g., flowering in June, purple flowers), and morphology (e.g., compound/deeply lobed leaves, alternately arranged). With each answer, the list of plants gets smaller and smaller until in most cases it’s simple to either scan through a small set of photos to find the match, or if the set is ten or fewer species, to navigate the app’s instant key that uses the dichotomous keys for just the species matching your answers.  More details about how to use the graphic key can be found in the FloraQuest app under “… More” then “How to Use the Graphic Key.”

In the plans for 2024 and 2025 include completing additional keys (within the big keys and genus keys), continuing to redesign and further improve many of the “older” keys, supplementing habitat descriptions, and additional FloraQuest apps covering the remaining parts of the Southeastern United States.

↑ Back to top of page

A final note

A flora is not so much proscriptive as suggestive. In something as complex and understudied as the plant life (10,000 species strong) of the diverse southeast, there is no One Truth, but a best approximation at this point in time – a compilation that makes useful the accumulated (but often conflicting) ideas about what the plants of the region are, their habitats, distributions, and best means of identification. This Flora is our critical, creative compilation -- based on over 7000 scientific papers, untold numbers of specimens, 48 years of field exploration of the region, conversations with other botanists, and teaching about the flora in the classroom and the field.

We still have a lot to learn (we still don’t know jack).  

Thanks for your support for this work!

Alan Weakley & the Southeastern Flora Team*

UNC-CH Herbarium (NCU) / North Carolina Botanical Garden

University of North Carolina at Chapel Hill

*The Southeastern Flora Team: M. Lee, S. Ward, J.C. Ludwig, D.B. Poindexter, B.A. Sorrie, E. Ungberg, R. LeBlond, J.C. Kees, C.A. McCormick, S. Oberreiter, R. Lance, H. Ballard, R. Carter, M. Pyne, W. Knapp, K. Bradley, S. Zona, W. Barger, L. Musselman, P. Schafran, D. Spaulding, J. Nelson, E. Keith, G. Fleming, D. Estes, L. Majure, H. Medford, E. Bridges, R. Folk, Z. Murrell, R.K. Peet, J. Townsend, G. Nesom, A. Floden, J. Horn, E.E. Schilling, J. Triplett, T. Murphy, Z. Irick, K. Schoonover McClelland, M. Alford, M. Brock, B. Keener, H. LeGrand, T. O’Brien, T. Witsell, and others.

↑ Back to top of page

Citing the Flora

In the case of the Flora of the southeastern United States web app, please cite as

In the case of the full flora PDF, please cite as

In the case of derivative (subset) PDF floras covering smaller areas (subregions or states), please cite as

In the case of the FloraQuest app, please cite as

↑ Back to top of page

PREFACE

In the nineteenth and early twentieth centuries, the botanical exploration of a region and writing a flora to summarize that information was seen as a basic societal need leading to the discovery of economically valuable information. Financial support for the research and writing of floras has waned in recent decades, though, as they have been increasingly regarded as “old science” and resources have shifted to areas of plant science seen as more “cutting edge”. Even in taxonomic research, the advent of molecular techniques has largely supplanted detailed taxonomic research (at generic levels and below) and the writing of floras, and the great majority of papers in plant systematics now address phylogenetic relationships within a particular group of plants, and mostly at higher taxonomic levels. Traditional monographic taxonomy, with descriptions of taxa, keys to facilitate their identification, distribution maps, and assessments of habitat and relative abundance or rarity, has become increasingly rare.

Yet, paradoxically, the societal uses and needs for the translation of taxonomic information to a useable form, such as floras, have never been greater. Globalization of human societies and economies has meant that plants are regularly introduced far away from their regions of nativity, and many become established and can be either benign or cause economic and conservation damages. Increasing human utilization of land resources has fueled a biodiversity crisis, with many species now imperiled. In the United States and elsewhere, this has resulted in considerable governmental and nongovernmental activity focused on biodiversity inventory and conservation, “recovery” of endangered and threatened species, ecological studies and ecological restoration, and assessment and suppression of invasive exotics. All these activities require an accurate and sophisticated understanding of the flora of an area. These activities also generate new information about the taxonomy, distribution, and conservation status of components of a region’s flora which then needs to be incorporated into new iterations.

In the southeastern United States, the publication fifty-five (56) years ago of the Manual of the Vascular Flora of the Carolinas, by A.E. Radford, H.E. Ahles, and C.R. Bell (Radford, Ahles, & Bell 1968), was a landmark. In the more than a half century since its publication, it has served as the primary reference for the identification of plants in the Carolinas, and throughout the southeastern United States (since most other states were not covered by comparable, “recent” references). The effort to research and write the Manual of the Vascular Flora of the Carolinas took about 11 years, and resulted in a series of publications, the Guide to Vascular Flora of the Carolinas (Radford, Ahles, & Bell 1964), the Atlas of the Vascular Flora of the Carolinas (Radford, Ahles, & Bell 1965), and finally the Manual itself (1968). Once published, the existence of “the Manual” helped generate an interest in and further studies of the flora of the region; since then, many additional species have been documented as part of the region's flora, additional alien species have become naturalized, new species have been described, monographs have given new taxonomic insights into groups, nomenclature accepted in 1968 has been found to be invalid, new and more reliable keys have been developed, and systematic treatments have changed and advanced. Increasingly, identification of the flora of our region by academic researchers, agency personnel, and the interested public is hampered by the lack of an up-to-date flora. Without such a flora, identification must involve reference to herbaria and thousands of monographs, papers, and other floras – resources not readily available to many people who need them. The absence in the region of a single-source modern standard for the systematic treatment, nomenclature, and identification of the flora compromises scientific studies, ecological research, and agency inventory, management, and monitoring of ecosystem and species biodiversity.

The Flora includes treatment of all vascular plant taxa in the flora region of Alabama, Arkansas, Delaware, District of Columbia, Florida, Georgia, Kentucky, Louisiana, Maryland, Mississippi, New Jersey, North Carolina, Pennsylvania, South Carolina, Tennessee, Virginia, West Virginia, and varying portions of the additional states of New York, Texas, Oklahoma, Kansas, Missouri, Illinois, Indiana, and Ohio (see Figure 1). Approximately 10,000 taxa are keyed and treated, making the Flora a comprehensive resource for understanding the flora of all the southeastern United States east of the “dry line” and south of the glacial extent.

 

↑ Back to top of page

Sources of information.

This new flora is based on all resources available: herbarium specimens, published literature, grey literature, Natural Heritage databases and rare species lists, and personal communication with a regional network of botanists and taxonomic experts. Herbarium specimens have been consulted at major institutions in the region. Increasingly, portals of digitized herbarium specimens (such as the SERNEC portal) and iNaturalist records (with appropriate vetting of ID and “wildness”) are also important sources for understanding the distribution, rarity, and naturalization/invasiveness of species in our flora.

↑ Back to top of page

Criteria for inclusion of taxa

One of the first challenges that the author of a flora encounters is to decide the criteria for the inclusion of taxa. The general rule in most floras can be simply summarized as “all native taxa and naturalized alien taxa,” but within this simplistic phrase hide many complicated issues, and floras often differ widely in the actual criteria and judgments that they apply (Pyšek et al. 2004; Palmer, Wade, & Neal 1995). In particular, coverage of alien species is very uneven in floras, and the frequent exclusion of many alien species from floras hampers ecological studies, conservation efforts, and efforts to minimize the ecological and economic impacts of invasive aliens.

The following categories of taxa are included and treated fully as “primary” species:

  1. Native taxa documented from the Flora region, whether extant or presumed extinct. Some authors, such as Isely (1990), have “excluded” taxa from a flora if they believed them to be extinct or extirpated. This philosophy seems poorly considered: these taxa may prove not to be extinct or extirpated and their inclusion in the Flora will facilitate possible rediscovery. Even if never found again, specimens of them in the herbarium need to be identified or confirmed, and their former existence in the region should be documented.
  2. Alien taxa introduced by whatever means and demonstrably established and reproducing (sexually or vegetatively) as a component of the flora. Parallel to #1 above, established alien taxa which have been presumably eradicated (such as Striga asiatica in the Carolinas) are included, as their eradication may not have been effective, they may be reintroduced, specimens need to be identifiable using the Flora, and their former existence should be documented.
  3. Alien taxa substantially cultivated in the Flora region as crops, such as Triticum aestivum, Zea mays, Vitis vinifera, and Pinus clausa. Such species are variably represented in herbaria, and are often included in floras only if one or more herbarium specimens indicate that the species is persisting, or has been collected around a dump or in the edge of a field “out of cultivation.” This seems an arbitrary criterion to apply to species which are among the most commonly seen and economically most important in a region, and may cover many thousands of acres or square miles in the region covered by the flora.

Additional categories of taxa are included and treated as “secondary” species:

  1. Native taxa with uncertain documentation, this varying from literature reports not definitely verifiable with specimens (some of these old and some new), to sight reports regarded as probably correct. Taxa in this category are included as secondarily-treated taxa, and their imperfect documentation is described.

Species which have been reported from the Flora region but which are excluded for one reason or another are also listed and the reason for their exclusion mentioned or discussed.

Taxonomic philosophy. Taxonomic treatments generally follow recent monographic and revisionary work, but an effort has been made to provide a certain rough consistency of “splitting” vs. “lumping” across different taxonomic groups. As is generally true in recent treatments, generic and family concepts are often narrower than those used in the Radford, Ahles, and Bell (1968) Manual, based on new evidence, including (but not limited to) phylogenetic analyses. Ironically, these results have often resulted in a validation of earlier, narrower generic (and familial) concepts espoused by J.K. Small, P.A. Rydberg, and others (see Weakley 2005 for extensive discussion). Varieties are less frequently recognized than by Fernald (1950), though a considerable number of species and infraspecific taxa “lumped” by Radford, Ahles, and Bell (1968) are recognized (generally following more recent monographic or revisionary work). Some taxa not formally recognized are discussed and characters for their recognition provided in the text, to draw attention to putative taxa that may warrant recognition after further evaluation.

↑ Back to top of page

Detailed dichotomous keys

Keys have been subjected to rigorous testing in the field and herbarium by hundreds of users; still, most can still use improvement. To the degree feasible, keys are structured to emphasize characters that are readily observable and available for long parts of the year, such as vegetative characters; this is not feasible for all groups, of course. Multiple characters are provided. Terminology strives to avoid abstruse technical terms which do not significantly add meaning (for some genera, an introduction to morphological characters and terms used is provided as “Identification notes” preceding the key). Geographic distributions and habitats are sometimes included in the keys as pragmatic, useful, secondary “characters,” but are placed in brackets to indicate that they are not “true” characters. The keys include (or are in the process of including) all species from the Flora region. In some cases, several alternate keys are provided. The primary emphasis of the keys is pragmatism – effective and efficient identification. For this reason, a key to a genus sometimes includes closely similar taxa not in the genus that may be mistaken for it. Another example is that the “family key” to ferns and fern allies is actually a key to genera, allowing an emphasis in the key on readily observable characteristics, rather than the technical characters often needed to distinguish fern families. Keys are based on herbarium specimens, though reference is made when characters based on live or fresh plants may differ from those of pressed and dried specimens. Some keys have been adapted from literature cited; where the adaptation is particularly close, credit is given to the source by specific citation.

↑ Back to top of page

The species account

The following types of information are listed (with prefixes in parentheses). Further descriptions of each appear in paragraphs below this list:

Native status. An asterisk prior to the species’ name indicates that it is considered exotic throughout the FSUS area. Some past Floras were haphazard in their inclusion of this information, which is a very important attribute of each recognized taxon. If there is a question, it is mentioned or discussed. For exotics, an opinion is given as to whether the taxon is naturalized, persistent, waif, etc. in the region.

Common Name(s). Common name(s) appear in Small Caps.

Distribution of species (Dist). A statement of the range wide distribution of each taxon treated is provided. This is based on published distribution maps and distribution statements in other floras, amended and improved by additional herbarium specimens and published records (such as the “Noteworthy Collections” section in the journal Castanea). See below for an explanation of the distribution maps.

Habitat (Hab). Information is provided about the habitat of the taxon. This information is largely from the field experience of the first author, supplemented by information from other botanists, from herbarium labels, and from the literature. For species with wide ecological amplitudes, the habitat may be described simply and broadly (“a wide variety of upland forests”), while the habitat of more localized, specialized, or rare taxa may be described in considerable detail (“moist outcrops of calcareous to semi-calcareous metamorphic rocks, such as mylonite or marble, near waterfalls in humid escarpment gorges with high rainfall, at low elevations”).

Flowering/fruiting dates, Phenology (Phen). Flowering and fruiting dates are provided for the FSUS area. These are derived from herbarium specimens viewed by the first author (collected from within the FSUS area), from field observations by the first author (within the FSUS area), and from literature cited. These dates may differ from the Delaware specific phenology as species may flower earlier (or less commonly later) in parts of the FSUS area.

↑ Back to top of page

Distribution Maps

The distribution statements in the species account are augmented by a map; see Figure 4 for symbology used. The map shows distribution within the Flora area symbolically, with each state × physiographic province area. The native/alien status of the taxon is shown by squares for native occurrence and triangles for alien occurrence. Note that some species have distributions including both alien and native distributions, so Dionaea muscipula for instance is native in the Coastal Plain of NC and SC, but alien in the Coastal Plain of FL and NJ.

In the lower left and right corners are spaces that also provide distributional information. If the species is endemic to the Flora region, you will see "EN." If the species is alien, you will see the region of the world to which it is native. If the species is native but not endemic, you will see a compass rose. Seven arrows depict the native distribution of the taxon outside of the Flora region. Arrows can be long (common at least somewhere in that region), or short (only uncommon or rare in that region).

The regions to which the eight arrows point are:

Please see the map legend for a table that describes all symbols on the maps as well as the arrows.

↑ Back to top of page

Literature

Nearly all genera have citations to recent, pertinent systematic literature, as well as more limited citations to literature on ecology and population biology. The intent is to provide the user with access into more detailed literature, and to document the literature basis of the treatment followed in the Flora. About 5164 references have been consulted and are cited.

Synonymy (Syn). Cited synonymy is provided to regional floras, monographs, revisions, and other significant floristic and monographic treatments (over 5000 references are used), at the end of the account and encoded in brackets: […]. This allows comparison of the taxonomic treatment in the Flora to other treatments, and convenient access to the taxonomic opinions and additional information available in those other treatments.

Synonymy is (or is in the process of being) provided comprehensively for the following floras:

All names known to me to be attributed to the Flora area in the other floras cited above, significant monographs and revisions, and important regional publications are accounted for, from Small (1913, 1933) and forward in time, with the exception that the process has not yet been completed for several floras.

It is important to recognize that this is not a conventional “synonymy” listing, but a concept-mapping that provides additional information on the details of the relationship between each taxon-represented-by-a-name in this Flora, and each taxon-represented-by-a-name in the other 5000 taxonomic references whose concept intersects the 10,000 taxa in the Flora. Prior to the name cited, a symbol is inserted to convey the conceptual relationship of the two names – in other words, the relationship of the name and associated taxonomic concept being applied in the Flora to the name and associated taxonomic concept in the other references, regardless of the nomenclatural relationship of the two names. “=” means that the two concepts are believed to be identical (the names may differ by rank, spelling, or genus, but the conceptual entity is the same). If the taxonomic concept is identical and the name is also the same, the name is omitted. “<” means that the name in use in the Flora is finer than (a split relative to, and wholly included within) the name as used in the reference(s) listed (once again the names may differ by rank, spelling, or genus – or be exactly the same, even though the concept differs). “>” means that the name and associated taxonomic concept in use in the Flora is broader than (a lump relative to, and wholly including) the name as used in the reference(s) listed. “><” means that there is a complex and cross-cutting relationship between the name and associated taxonomic concept used in the Flora and the name and associated taxonomic concept used in the reference(s) listed. “?” means that the relationship between the taxonomic concepts is not understood by me (or at least has not been indicated here) at this time (often this means that there are complications outside the flora area, and often outside of North America, that make the concept relationship difficult to determine or characterize simply).

↑ Back to top of page

Conservation Information

NatureServe Global Conservation Status Ranks (GRank) and US Endangered Species Act (USESA) Listed Species. These statuses are provided by NatureServe for all species that can be easily and unambiguously crosswalked between the Flora and NatureServe’s taxonomic concepts. In the previous version of the Flora, we crosswalked based on exact name matches. In this version, we crosswalked using the synonymy data in the Flora, and resulted in many new matches from unambiguous name changes (e.g., Benthamidia florida). It also created situations where a rank was no longer displayed for exact name matches that are taxonomically ambiguous (e.g., Andropogon glomeratus). The ranks provided are current as of the publication of this version of the Flora. For more information on Global Rank definitions, updates, additions, and supporting documentation, see NatureServe Explorer (explorer.natureserve.org), accessible for each species through a link in the PDF version of the Flora. Entries missing Global Rank or USESA status may reflect taxonomic ambiguity and should not be assumed to be secure or not listed.

↑ Back to top of page

Comments

Comments and discussion (Comm) and Taxonomic Comments (Tax). Miscellaneous comments and discussion are provided for many species and genera, including discussion of biogeography, more details on distribution of rare species, additional notes on identification not included in the keys, information of particular interest on species biology and ecology, habitat, uses, discovery in the flora area or a state, etc. These “idiosyncratic comments” add to the general usefulness and interest of what is intended to be a rigorous, practical, and interesting flora.

Identification Notes (ID Notes).  This field is intended to provide information helpful to the flora user in recognizing the taxon (species, genus, or family) and distinguishing it from other (related or not) taxa of the same rank, without simply restating the key.  This can partly be a “word painting” of the genus, an account of how an experienced botanist recognizes the genus, especially based on “gestalt” and without a focus on technical characters.  How would a less experienced botanist (but not necessarily a complete novice) recognize the species, genus, or family?  Note that some taxa cannot be readily described in this way.

Key Advice (Key). This field is intended to describe for a family or genus the characters that are needed to use the key and identify the taxa at the next lower rank (e.g. genera of the family or the species of the genus), focusing on characters that are of particular note in that group.  Any special, detailed, or idiosyncratic use of terminology should be explained.  Details can be provided about how to measure particular features, or techniques needed to observe a particular character.  If the user is making an herbarium specimen, making a photographic observation (like iNaturalist), or taking notes to enable later identification of a plant seen in the field, what characters do they need to be sure to include in their specimen, photographs, or notes?

↑ Back to top of page

Wetland Indicator Status

These are from the USDA PLANTS database, and designate a species' preference to occur in a wetland or upland. More information about the values and their regions may be found on their website (plants.usda.gov). That database records taxa at the species level, and as such we note if there may be taxonomic ambiguity between our set of taxa and theirs.  The 5 possible values are:

↑ Back to top of page

Heliophily

Heliophily Index (Helio). The degree to which a species has fidelity to or requires light for its growth, reproduction, and success. The scale is 1-9, so that all ratings are single digit.  Essentially, a 9 rating means the species is a “sun obligate”, and a rating of 1 means the species is a “shade obligate”. By obligate, we mean that the species requires those conditions and will not survive, or at least successfully reproduce, under contrary conditions.  Non-native species are not assigned heliophily indexes, and to note this we supply the value 0.  A few examples:

More on heliophily

↑ Back to top of page

ACKNOWLEDGMENTS

I began this project 36 years ago (in 1988) and have managed it to provide an openly and freely available resource, with updated versions posted and available for download. An important goal throughout has been to incorporate the insights of all knowledgeable students of the flora of the region – professional and amateur, non-academic and academic, taxonomist and natural historian – and to access information from traditional sources for floras (herbaria, journal articles, other floras) as well as less traditional sources (gray literature, agency reports, and increasingly botany-oriented Facebook groups, and citizen science platforms like iNaturalist). Each contributor of particular treatments is listed in the table below.

Financial Support

Huge thanks to all our financial supporters, including those who have made donations to the Friends of the UNC Herbarium fund, and to those who are members of and donors to the NC Botanical Garden. Special thanks to an anonymous conservation philanthropist whose generous donation created the opportunity for us to make the FloraQuest app as well as the web app. We are deeply grateful for your belief in us and the impact these products can make to positively affect conservation and our society’s collective knowledge and appreciation of the flora of our area!

Great Places to Botanize

We are greatly indebted to the botanists and ecologists who provided guides to some of the best botany sites in our region. This resource is available on both the FloraQuest app and the web app, but is too long for inclusion in the PDF. These contributors included Christopher Benda, Jim Brighton, Misty Buchanan, John Burkhart, Linda Chafin, Gary Fleming, Rick Gardner, Andrew Gibson, Steve Grund, Mike Homoya, Wes Knapp, Tara Littlefield, Paul J. Marcum, Elizabeth Matthews, Bill McAvoy, Scott Namestnik, Damien Ossi, Michael Schafale, Sam Tessel, Vanessa Voelker, Kathleen Strakosch Walz, Scott Ward, and Steve Young. In addition, many of these contributions were facilitated by key organizations including the Delaware, Indiana, New Jersey, North Carolina, Ohio, Pennsylvania, and West Virginia Natural Heritage Programs, the U.S. National Park Service, the Washington D.C. Fisheries and Wildlife Division, the Office of Kentucky Nature Preserves, the Maryland Biodiversity Project, Georgia Native Plant Society, NatureServe, the Illinois Natural History Museum, the Pennsylvania Vascular Plant Technical Committee, and the Flora of Virginia Project.

Beta App Reviewers 

We recognize the invaluable contributions of our beta testers of FloraQuest, particularly Stephen Bowling, John Bunch, Josh Copen, Mark Connolly, Jonathan Drescher-Lehman, Ben Heuser, Kevan Schoonover McClelland, Jon Titus, Priscilla Titus, James Vanderhorst, among many others. We are grateful for their support, as their time, effort, and feedback were instrumental in helping us improve the features within the apps prior to their official launch.

Photographs 

The web app and FloraQuest feature photos for nearly all common species in the northern part of the flora and the vast majority of the remaining species. We acknowledge the contributions of over 800 photographers who so generously shared their photos with us for this project. In particular, we acknowledge the following photographers and illustrators for the quality, quantity, and taxonomic breadth of their documentation: Gary Fleming, Scott Ward, Alan Cressler, Erik Danielson, Keith Bradley, Richard and Teresa Ware, Bruce Sorrie, Jay Horn, Aidan Campos, Alan Weakley, Paul Marcum, Sonnia Hill, Joey Shaw, John Gwaltney, James Hardin, Edwin Bridges, Floyd Griffith, Will Stuart, Ron Lance, Grant Morrow Parkins, Eric Keith, Zihao Wang, Brandon Corder, Jake Smith, Eric M. Powell, Nathan Aaron, SOS Collectors, Janet Wright, Emily Oglesby, Theo Witsell, Alvin Diamond, Dan Spaulding, Bonnie Semmling, Michael Oldham, Sam Kieschnick, Patrick Hacker, Jim Keesling, Matt Reala, Brett Budach, Alex Graeff, Patrick McMillan, Stephen Thorpe, Brian Finzel, Jim Fowler, Alison Northup, Eric Ungberg, Roger Hammer, Sequoia Janirella Wrens, Andrew Conboy, Nate Hartley, Matt Berger, Armin Weise, Joseph Montes de Oca, Yves Bas, Douglas Goldman, Jeffrey S. Pippen, Melanie Flood, Lowell Urbatsch, and Marion Seiler and Peggy Kessler Duke (Radford, Ahles and Bell line drawings), among many many others.

iNaturalist 

We thank iNaturalist for their service provided to naturalists around the world, and for enabling the exchange of open-source biological information and diagnostic plant photographs throughout the southeastern United States and beyond. We specifically thank the users of iNaturalist with their photo attribution licenses set to open licenses like Attribution and Public Domain, allowing us open access to thousands of photographs which can be particularly helpful for non-native waifs that often lack images among southeast botany photographers. In addition, we also thank the users of iNaturalist with some rights reserved who cheerfully gave permission to use their photos upon request, and we encourage future users of this app who also use iNaturalist to consider changing their photo attribution within their account settings.

Photographs from iNaturalist are licensed according to the Creative Commons license. For FloraQuest, we use photographs with licenses of (any combination of) Attribution, Public Domain, No Derivatives, and Share Alike. We include some images with Non Commercial licenses, but only for photographers who granted us direct permission to do so. For the free web app, we add photos licensed for Non Commercial use. For licensed photographs, we include a link to the original source of the photograph(s) if used in FloraQuest or the web app. No derivative work has been made from iNaturalist photographs used in FloraQuest; we have only resized images for app optimization, or rotated images that were incorrectly displayed in iNaturalist. All other images in FloraQuest are copyrighted by the original photographer and may not be reused without permission from said photographer. 

Photo Annotation 

In addition to the contributions of our many photographers, we acknowledge the countless hours of annotation work undertaken by North Carolina Botanical Garden staff and volunteers to sift through our original photo batches and correctly label botanical characters featured within our highest quality photos (flowers, leaves, buds, bark, vestiture, etc...). This annotation work enabled us to efficiently select the best photos for use within FloraQuest and the web app, and also point us in the direction in which our biggest photo gaps remain. Their due diligence accounted for the annotation of over 63,000 images. We are grateful for our most prolific annotators: Aria Searles, Janet Whitesides, Laura Cotterman, Liz Henderson, Madi Radford, Margot Ringenburg, Michael Lee, Paula LaPoint, Scott Ward, Shanna Oberreiter, and Susan Baker. We will continue to gather, annotate, and select images for the remaining regions of the Flora of the Southeastern United States in subsequent FloraQuest app releases.

Contributor Taxa covered Families/Genera
M. Alford38Xylosma, Salicaceae, Casearia, Flacourtia, Oncoba
H. Ballard78Viola
W. Barger32Lobelia
K. Bradley51Evolvulus, Scutellaria, Dodonaea
E. Bridges18Pityopsis, Elytraria
M. Brock27Silphium
A. Campos62Cactaceae
R. Carter28Cyperus
D. Estes28Clematis, Penstemon
G. Fleming29Stachys
A. Floden7Trautvetteria, Blephilia
R. Folk17Heuchera
J. Horn5Stillingia
Z. Irick34Clematis
J. Kees184Cyperus, Oenothera, Symphyotrichum
W. Knapp56Juncus
R. Lance111Crataegus
R. LeBlond338Scleria, Paspalum, Coleataenia, Dichanthelium, Panicum, Rhexia, Rhynchospora
L. Majure22Opuntia
H. Medford21Smilax
T. Murphy34Clematis
Z. Murrell14Cornaceae
L. Musselman32Isoetes
J. Nelson29Stachys
G. Nesom9Ligustrum
R. Peet13Carya
D. Poindexter395Cornaceae, Abies, Scutellaria, Stachys, Taenidia, Carex
M. Pyne71Solanum, Physalis
P. Schafran32Isoetes
E. Schilling4Blephilia
R.K. Schoonover McClelland12Trichostema
B. Sorrie719Scutellaria, Lobelia, Coreopsis, Euthamia, Carex, Viola, Pityopsis, Diodia, Juncus, Myriophyllum, Sabatia, Sisyrinchium, Viburnum, Buchnera, Eleocharis, Lechea
D. Spaulding32Lobelia
J. Townsend10Boltonia
J. Triplett4Arundinaria
S. Ward419Orchidaceae, Asteraceae, Eleocharis, Salix, Euphorbia, Koeleria, Sphenopholis, Trisetum, Urochloa, Paronychia, Limnophila, Senega
S. Zona33Arecaceae

↑ Back to top of page

THE “BIG KEY”: KEY TO FAMILIES (AND IN MANY CASES GENERA), AND GENERAL ADVICE ON USING A DICHOTOMOUS KEY

General advice on keying. The keys in this Flora are artificial and unabashedly pragmatic. One can get to the sub-keys (Key A, Key B, Key A7, etc.) by proceeding through the general key, or by jumping directly to the sub-key based on its “description”. In order to accommodate both access methods, some taxa are keyed in 2 or more sub-keys, but would logically be found only in one sub-key if one proceeded accurately through the general key. For instance, floating aquatic pteridophytes are keyed in both Key A2 and Key C1, though a logical procession through the general Key would key them into Key C1 and not allow them to appear in Key A2; they are keyed as well in Key A2, so that if it is apparent or determinable to the user that they are vascular cryptogams, they can be found via that key as well.

Identification keys are a time-honored and useful way to arrive at a tentative decision about the identity of a plant in the field, on an herbarium sheet, or in an image. A key is essentially a decision tree, where you are presented with a series of dichotomous (“choose A or B”) choices that arrive eventually at an “answer”. “Keying” takes some practice, though, and we here provide some advice and information to help you use the keys in the Flora of the Southeastern United States. The keys in this book are indented keys, which take more space but provide easier visual understanding of the structure of the key and make it easier to backtrack, when that is needed, or to look ahead, which is often helpful, particularly for those who are more experienced with the plants of Virginia. Each choice in the decision tree (key) is represented as a couplet with 2 leads. Each couplet in a key has a unique (and sequential) number, which reduces errors in following the key, particularly in longer subkeys, in which the two leads to be compared may be some distance apart and even on different pages. Some characters require some magnification; a high-quality 10× hand lens is adequate for use of the Key to Genera and Families and for use in nearly all the subsequent keys to genera and species in the families (greater magnification and a dissecting scope are helpful or necessary in some families and genera with small, “technical” features).

It is important to read both leads of a couplet and to make a choice based on the preponderance of the evidence. In most couplets, 2 or more characters are used, and the character states of each of those characters are contrasted. Sometimes the contrast for a particular character may be an incomplete one, such as “petals 4 or 5” vs. “petals 5 or 10” – if your plant has 4 or 10 petals, the choice based on that character is clear, but if your plant has 5 petals, this character provides no useful information for you and you will need to rely on other characters used in the same lead. This illustrates the problem of just reading the first lead and making a snap decision (“oh, it has 5 petals, so I will choose the first lead”). Many couplets use one or more characters that may not be available on your specimen, or at least not readily determinable, such as the number of petals on a plant in fruiting stage, or the fruit type on a plant in flowering stage (though see “Sleuthing Characters” below for some advice on determining character states that may not be readily apparent). Occasionally, you may run into a couplet which represents a “dead end” for you, in that the plant you are keying does not have the feature(s) you are asked to judge (e.g., the petal number of a plant not in flowering stage). A “dead end” does not mean that you cannot arrive at an “answer”, though it does make it somewhat more difficult. In this situation, as well as in any situation in which the choice between the two leads of a couplet is somewhat or completely ambiguous, it is a good idea to record or remember the location or identity of the ambiguous couplet (“Key N1, couplet 11”), take one lead and see what answer results, then take the other lead and see what answer results. Occasionally, the answer will be the same (some species and genera are keyed in multiple places), but often this will lead you to two contrasting potentially correct answers which must then be compared (see below for advice about testing the “answer” arrived at in a key). Often, you will get an indication that one way is the wrong way because you will be confronted with couplets that do not make sense relative to the plant you have in hand.

The Key to the Genera and Families has been structured in a somewhat novel way, emphasizing vegetative characters (those not involving flowers and fruits). Many professional and amateur users of floras nowadays need or want to name plants throughout the growing season, and not only during the somewhat short periods of time when flowers or fruits may be present on the plant. For this reason, more readily observable features of the growth form of the plant, the arrangement of the leaves, whether it is woody or herbaceous, a vine or not, and other characters that are readily observable over a long period are used as much as possible in the keys, and those vegetative characters are especially used in the early portions of the keys, so that based strictly on more observable and less “technical” characteristics, you can key down to an answer or at least to a relatively small subset of the species in the Flora. In other words, we have tried to minimize the use of difficult choices, ambiguities, and technicalities at all, but when they have proven necessary, we have “pushed them” as far down into the latter parts of keys as possible, so that if a true “dead end” is reached in the key, an identification can possibly be made based on comparison of the relatively few possibilities remaining.

Confirming identifications. Identification keys are a tool, but not an infallible one, and it is therefore critical to confirm your identifications. It is easy to make the dangerous assumption that “it keys to it, so it must be it”. You may have made a simple error (such as jumping down a line in the key), or an error of interpretation in deciding between the two leads. The key may be imperfect, having failed to accommodate an unusual species or genus, or unusual conditions (character states) in a species or genus (e.g., abnormally large leaves, leaves whorled by developmental anomaly in a typically opposite-leaved species, etc.). Or, you may have found a native or alien species not known before from Virginia and therefore not provided for in the key! For these reasons, it is important that you compare your “answer” from keying to descriptions, drawings, and photographs in various sources (including the photographs and line drawings in the digital forms of the Flora of the Southeastern United States), to written technical descriptions and drawings in other floras (increasingly available online, such as the Flora of North America), to specimens in area herbaria, and to photographic images available in other books and online.

Leaf arrangement. The arrangement of leaves (alternate, whorled, or opposite) and their disposition (basal or cauline) is used frequently in the keys. Alternate leaves are attached at the stem 1 per node, opposite leaves 2 per node, and whorled leaves 3 or more per node. Note, however, that alternate leaves are sometimes closely clustered (with very short internodes) and mistakable as whorled or opposite. Note also that some plants (Hypericum, Eupatorium, many Lamiaceae, many others) have a strong tendency to have axillary shoots in the axils of primary leaves; these are often referred to as axillary fascicles. These can superficially make it appear that there are many leaves at a node. Axillary fascicles tend to have smaller leaves (at least for a time) than the primary leaves and tend to have short and compressed internodes; these should not be interpreted as whorled if the primary leaves are not whorled. Also, many herbs with opposite leaves have occasional developmental “errors” that result in the leaves being in whorls of 3; these cannot be reliably accommodated under “leaves whorled” choices in the key, so if a plant with whorled leaves does not key well under “leaves whorled”, it should also be sought under “leaves opposite”.

Leaf duration. The longevity of leaves is used in the keys for woody plants. Evergreen plants are those that retain full leaf cover through the winter, while deciduous plants lose their leaves at the end of the growing season (for some species, sometimes well before autumn). Some plants are also described as tardily deciduous or semi-evergreen, meaning that they drop leaves gradually into the winter, so that they are sparsely bedecked with leaves or even bare by the time of initiation of new growth in the spring. Unless you are in a position to observe the plant repeatedly through the seasons, leaf duration must be interpreted, and this can be difficult, especially on herbarium specimens. In general, evergreen leaves tend to be darker green (at least on the upper surface), often shinier, and usually thicker in texture and stiffer than deciduous leaves, but there are exceptions to all these tendencies. It can be helpful to see if the specimen or living plant has two obviously different ages of leaves present: older, tougher, more ragged and insect-eaten leaves of last year as well as younger leaves of the year. On many woody plants, it is easy to determine what is new (this year’s) growth from older growth, and the younger vs. older leaves may be spatially separated on shoots of the season vs. on older wood. Note, though, that some “evergreen” shrubs or trees essentially replace all their leaves at leaf-out in the spring, all of last year’s leaves being sloughed as the current year’s leaves are emerging.

Growth form or habit. The basic growth form or habit of the plant is used extensively in the keys. Woody plants have substantial secondary or diameter growth of wood, which makes their stems (in general) thicker, stronger, stiffer, and tougher; they also have “perennating structures” (normally buds) borne above ground on their woody stems. Woody plants are further subdivided into trees, shrubs, rosette shrubs, subshrubs, rosette subshrubs, and lianas. Trees are generally more than 5 meters tall at maturity and usually have single stems which are not interconnected by subterranean rhizomes (forming clonal patches). However, some tree species are characteristically multi-trunked or tend to produce a multi-trunked growth form as a result of stump-sprouting following logging, and stressful ecological conditions (such as shallow soil over rock or maritime exposure) can produce trees shorter than 5 meters. Shrubs are generally less than 5 meters tall and are often multi-stemmed from the base or near it (though some shrubs are characteristically single stemmed); quite a few are also clonal and produce many above-ground stems from a series of interconnected underground rhizomes). Some species grow as both trees and shrubs or have an ambiguous form; these are generally keyed as both trees and shrubs. Note that trees have seedlings or saplings that are shorter than 5 meters tall and may be multi-stemmed in growth form, especially in burned habitats; these are not keyed as shrubs and can generally be recognized as tree seedlings or saplings by the presence in the habitat of adult trees of the same species and by their lack of sexual reproduction (flowers, fruits, cones, etc.) because of their juvenile condition. Subshrubs are somewhat to strongly woody, but short in stature (often < 2 dm tall); while they have woody growth, they are often mistaken for herbs. Rosette shrubs and rosette subshrubs have basal leaves (see Leaf location, below) from an above-ground but short woody stock. Lianas are woody vines: in essence shrubs with specialized structures for climbing, including a) adventitious roots, b) twining growth of main stems, or c) simple or branched tendrils that either twine themselves or have adhesive “holdfast” tips. Some plants are keyed both as lianas and as shrubs. Herbaceous plants lack substantial secondary growth of wood and are either annual or have perennating organs (such as buds) on subterranean rhizomes, crowns, caudices, or corms. Herbaceous plants are further subdivided into herbs and herbaceous vines. Herbs are erect, sprawling, or trailing, but lack specialized adaptations for climbing (twining, tendrils, etc.); whereas herbaceous vines have these specialized adaptations. The interpretation of “woodiness”, between shrub and herb (and liana and herbaceous vine), can be difficult, especially with herbarium specimens. Some herbaceous plants can become suffrutescent: tough, fibrous, or thick in ways that mimic or approach woodiness. The presence of vegetative buds (not flower buds) in the axils of leaves on the aerial stems clearly indicates a woody plant. Some plants which are ambiguously woody and likely to be mistaken one way or the other are keyed both ways.

Leaf disposition. The disposition of the leaves, whether basal or cauline, is used as a distinction to separate some of the major subkeys (in the woody plants separating Keys A7, B1, and E from the others, and in the herbaceous plants separating Key N from Keys O, P, Q, R, and S), as well as in a few other places. Basal leaves arise from underground buds (on rhizomes, crowns, caudices, or corms) or from the very base (ground level) of an aerial stem. Stem leaves (cauline leaves) are those which arise from above-ground (aerial) stems of the plant. Many plants, however, have basally disposed leaves, where the largest leaves are basal (and usually persistent through the growing season as a “basal rosette”), but smaller stem leaves extend up the above-ground stem. This can be ambiguous, though, and the persistence of basal leaves can be affected by season and conditions. While many taxa are keyed both in Key N and in one or more of Keys O, P, Q, R, and S), if this choice seems at all ambiguous and keying one way does not work well, the other choice should be tried.

Leaf type. Leaves are described as either simple or compound. Simple leaves are not divided into separate leaflets; the leaf tissue is continuous with all other leaf tissue of the leaf. By contrast, compound leaves are separated into 2 or more separate leaflets, connected only by various stalks (petiolules, rachises, rachillas) that lack leaf tissue. Simple leaves may be unlobed, pinnately lobed, or palmately lobed, and the lobes may be variously shallow or cut nearly to the midvein or base of the leaf. Perhaps the easiest way to determine whether leaf lobing is pinnate or palmate is to look at the major veins in the leaf. Pinnately lobed leaves have lobes arrayed in a line along either side of the midvein, and the lobes are associated with the major secondary veins of the (pinnately veined) leaf. The lobes of palmately lobed leaves are associated with the 3 or more palmate veins that arise together from the base of the leaf blade (note that the lobes of palmately lobed leaves are sometimes themselves sublobed, and that these sublobes are often pinnately arrayed: the leaf is still considered palmately lobed). Compound leaves are further classified by the number of leaflets, whether the leaflets are arrayed in a pinnate or palmate manner, and whether there is a single order of division or 2 or more orders of division. Palmately compound leaves have all leaflets attached at a single point, at the end of the petiole. Palmately compound leaves in our flora have from 3 to ca. 21 leaflets and are never further compound beyond the single order of division (in other words, the leaflets are not themselves compound). Pinnately compound leaves have leaflets attached to one or more axes (rachises, rachillas) that extend beyond the end of the petiole, and many taxa have 2 or more orders of division. Bifoliolate (2-foliolate) leaves are very rare in our flora. Trifoliolate leaves (3-foliolate, and sometimes called “ternate”) are very common in our flora and can be either palmately 3-foliolate or (especially in the Fabaceae) pinnately 3-foliolate. Pinnately compound leaves have a short rachis extending past the end of the petiole (and the point of attachment of the 2 lateral leaflets via their petiolules), with the terminal leaflet attached at the end of this rachis via its petiolule; the joint between the rachis and the terminal petiolule is usually obvious because of a change in diameter, color, vestiture, and/or texture. The distinction between palmately 3-foliolate and pinnately 3-foliolate leaves is not used in the Key to Genera and Families but is important in some other keys, especially the key to genera of the Fabaceae. Pinnately compound leaves with 4 or more leaflets are very common in our flora, especially in some families. Even-pinnately compound leaves (the less common situation) have an even number of leaflets, often paired along the rachis or rachillas, and lack a terminal leaflet at the tip of the rachis or rachilla and extending along its axis; these taxa are concentrated in the Fabaceae and a few other smaller families. Odd-pinnately compound leaves have a terminal leaflet and therefore usually an odd number of leaflets. Odd-pinnately compound leaves with 2 or more orders of division are typically described in the keys as complexly compound. Other floras variously describe leaves of this sort as 2-pinnate, 3-pinnate, decompound, biternate, or other terms, but these have largely been avoided in the keys in this work because the “compoundness” is often complex, mixed between pinnate and ternate, and therefore difficult to describe accurately with such terminology. For instance, many members of the Apiaceae have complexly compound leaves, which are initially 3-forked (ternate), each of these forks may then be 3-forked again (though with the lateral forks supporting fewer or smaller leaflets than the terminal one), and these 3-order divisions are then often pinnately compound. Note that deeply lobed leaves can sometimes be easily mistaken for compound leaves. Compound leaves have no leaf tissue connecting the individual leaflets, whereas lobed leaves have at least a narrow flange of leaf tissue along the rachis or rachilla that connects the leaf tissue of one lobe with the leaf tissue of the next. In some taxa, this is difficult to interpret, and these have generally been keyed both ways.

Lobes and teeth. The presence, absence, number, and shape of lobes or teeth along the margin of the leaf are very useful vegetative characters. The term “tooth” or “teeth” is here used in a broad sense to include any of the small marginal projections covered under the terms dentate, denticulate, serrate, serrulate, crenate, crenulate, spinose, spinulose, doubly serrate (biserrate), or erose. In other words, teeth can be rounded, pointed, or spine-tipped, and of various shapes and sizes. The term “tooth” or “teeth” does not include undulations out of the main plane of the leaf, hairs, or epidermal projections in the plane of the leaf margin, described by terms such as ciliate, ciliolate, or scabrous-margined. Teeth are often regular in size and position but in some species are irregular in form, shape, and even presence (these species are keyed in several places). The term “lobe” or “lobes” is also used in a broad sense to mean a larger feature of the leaf margin. Relative to teeth, lobes are typically both actually larger and relatively larger in relation to the size of the leaf, and also more widely spaced, often with a sinus (the depression between 2 lobes) extending 1/10th to 9/10th of the way from the outer leaf outline to the midrib. Lobes are typically spaced 1 cm or more apart, though the term is also applied to more closely spaced features with relatively deep sinuses (at least 3/10th of the way to the midrib), especially in pteridophytes and in flowering plants with small leaves. Teeth are truly marginal, typically meeting 2 or 3 of the following 3 conditions: spaced < 1 cm apart, the sinuses between them usually extending < 1/10th of the way to the midrib, and the tooth itself (measured on its shorter side if it not equilateral) < 4 mm long. Occasionally we have also used the number of “points” as a character in the keys. This is the total number of lobe points and tooth points along one side of the leaf (base to apex on one side of the midvein). Note that some leaves are unlobed except for the presence of 2 basal lobes (one on either side, often described as cordate, sagittate, auriculate, or hastate depending on the shape, size, and orientation of the lobes); this situation is not keyed in the “lobed” sections of the key (as noted in the pertinent couplets).

Learning families. Learning plant families, especially those that are particularly important in the Southeastern United States flora or that are especially distinctive, is an extremely useful aid in identifying plants. While “learning” a family often starts with understanding its distinctive characteristics, often including some rather technical characteristics, with experience it becomes a more “gestalt” sense that, for instance, “that plant just looks like Asteraceae”, even if the features that would allow it to be keyed are not present. Knowing plant families often allows one to bypass the Key to Genera and Families entirely or facilitates decisions at particular couplets in it. A few of the families that are particularly useful to learn are Apiaceae, Asteraceae, Brassicaceae, Cyperaceae, Euphorbiaceae, Fabaceae, Juncaceae, Lamiaceae, Poaceae, Ranunculaceae, Rosaceae, and Rubiaceae.

Sleuthing characters. Some characters used in the key may seem initially impossible to find on your plant or specimen, but may actually be findable or deducible. Old fruits can sometimes be found on woody species, or on the ground under the tree or shrub. Old flower stalks (from the previous year) are sometimes present in perennial herbs, allowing the size of the plant and the type of inflorescence to be assessed. The calyx is often persistent after the petals have fallen, and calyx merosity (number in the whorl) and symmetry is usually the same as the merosity and symmetry of the corolla (though not always). Various fruit characters can sometimes be deduced from the flowers, and various flower characters can be deduced from the fruits. When capsules are immature (sometimes even in the stage of an ovary while in flower), dehiscence can often be deduced by the presence of visible lines on the fruit (sutures, visible at 10×). The number of carpels and locules can usually be determined from either the ovary or the immature or mature fruit, by making a careful ×-section. Stamens are sometimes present as shriveled remnants on fruits, allowing the number of stamens to be determined. Hair types (e.g., simple vs. stellate) may seem impossible if the leaf appears superficially glabrous, but hairs often remain to the end of the season on even apparently glabrous leaves in protected places, especially on the lower surface in the main vein axils. The bulbous or papillose bases of some hairs remain after the rest of the hair has worn off. Deducing the presence of stipules is often possible by looking for scars (usually linear) that extend beyond the leaf scar proper.

Winter identification. Note that no attempt has been made to make the key work consistently for plants in winter condition. Woody plants with evergreen foliage will generally be “keyable” in Keys B, D, E, F, G, H, I, and J, but deciduous species will not; there are various winter twig and bud keys available in print and online for the winter identification of trees and shrubs. Herbaceous plants with winter rosettes or otherwise green winter foliage will generally be found in Key N, but an impractical number of ambiguous or “dead end” leads will be encountered.

Botanical terminology. While the use of specialized terminology and jargon has been reduced, some of these terms are useful and unavoidable, and provide a precise meaning without a lengthy explanation. Terms can be found in the glossary, and there are print and online resources that provide definitions and often illustrations as well. Particularly recommended at the time of writing is Harris and Harris (2001), Plant Identification Terminology: an Illustrated Glossary.

↑ Back to top of page

Characteristics of major groups of vascular plants.

At various points in the key, a kind of shorthand is used in key leads to indicate the main evolutionary group involved: Lycophytes, Pteridophytes, Gymnosperms, Basal Angiosperms, Eudicots, and Monocots. This shorthand is not placed in every couplet in which it could be, but is used where it is likely to be helpful to the user. While the readily visible characteristics of these groups have many exceptions, the following table} will aid in their recognition (note that this table is pragmatically based only on the characteristics of those taxa in our flora).

Lycophytes Pteridophytes Gymnosperms Basal Angiosperms Eudicots Monocots
Leaf size Very small (< 20 mm long), or linear quill leaves in Isoetes Very small scale to very large Very small scale leaves to very large pinnately compound leaves Small to large (> 3 cm long) Very small scale to large Very small scale to giant leaves
Leaf complexity Simple Usually complexly compound (1-5× compound), but also simple or variously less complicatedly compound Simple and scale-like or needle-like (or 1-pinnately compound in Zamiaceae and Cycadaceae, and fan-shaped and dichotomously veined in Ginkgo) Simple (or dichotomously compound in Cabomba) Simple to complexly compound Simple with few exceptions (except palmately or pedately compound in Arisaema and palmately or pinnately compound in the giant leaves of Arecaceae)
Leaf or leaflet toothing Entire or minutely toothed Often toothed (diversely so), but sometimes entire Entire or minutely toothed Entire Entire or variously toothed Entire (often marginally scabrous or ciliate; rarely with spinulose teeth in some aquatics)
Leaf or leaflet lobing Leaves not lobed (leaflets never present) Leaves and/or leaflets often lobed (diversely so) Leaves or leaflets not lobed Leaves not lobed (except the base sometimes cordate or auriculate) Leaves and/or leaflets often lobed (diversely so) Leaves or leaflets not lobed
Leaf arrangement Alternate, opposite, or whorled Alternate Alternate, opposite, whorled, or fascicled Alternate (rarely opposite, in Cabomba, Calycanthus, and Asarum) Alternate, opposite, or whorled Almost always alternate (rarely opposite or whorled)
Leaf disposition Cauline scale leaves (basal quill leaves in Isoetes) Basal Cauline (or basal in Zamiaceae and Cycadaceae) Cauline (or basal in Nymphaeaceae and Brasenia) Cauline or basal Cauline or basal
Leaf venation A single unbranched vein Complex and variable, often with some dichotomous portions Single midvein or several parallel (dichotomous in Ginkgo) 1° and 2° veins pinnate or palmate, ultimate veins netted or free 1° and 2° veins pinnate or palmate, ultimate veins netted or free 1° and 2° veins parallel or penni-parallel, smaller veins cross-veins at right angles
Reproductive structures Spores, borne in sporangia axillary to scale leaves (or in Isoetes embedded in the base of quill leaves) Spores, mostly borne on the undersurface of leaves, but also in a variety of specialized structures (but not as in Lycophytes) Seeds, borne naked on scales, or in berry- or drupe-like structures Seeds, borne in fruits Seeds, borne in fruits Seeds, borne in fruits
Perianth N.A. N.A. N.A. Typically many-merous, the segments borne spirally or in whorls Typically 4-5-merous (sometimes many), the segments in whorls Typically 3-merous, the segments in whorls
# of carpels N.A. N.A. N.A. Typically > 6 (rarely 1-6) Typically 4-5 or 1-2, sometimes many, very rarely 3 Typically 3 (rarely 1, 2, 4, or 6)
Carpel fusion N.A. N.A. N.A. Usually separate (sometimes fused) Usually fused, sometimes separate Always fused
Perianth connation N.A. N.A. N.A. Perianth segments typically separate (fused in Nymphaeaceae or Aristolochiaceae) Perianth segments often fused, but also often separate Perianth segments typically separate (sometimes fused)

↑ Back to top of page