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Hunt Institute for Botanical Documentation


Categorical Glossary for the Flora of North America Project

Compiled by Robert W. Kiger and Duncan M. Porter and published as the Categorical Glossary for the Flora of North America Project (2001), this selective glossary attempts to reconcile, integrate, and codify the traditional terminology of plant-taxonomic description, and should be especially useful for computer-based comparative databanking of such information.


This work has had a long gestation. It grew out of a coordinated outline and glossary for morphological and habitat description (Porter et al. 1973) produced while we were both with the Flora North America Program (original FNA, not to be confused with the current Flora of North America project) as Editor-in-Chief (Porter) and Associate Editor (Kiger). Together with the first part of the FNA guidebook (Shetler et al. 1973), that edition followed a seven-year period of planning and program design. That provisional version of the outline and glossary was the first product of an unprecedented attempt to reconcile, integrate, and codify the classical format and terminology of plant-taxonomic description, thus enabling computer-based comparative databanking of information on vascular plants.

Primary responsibility for the outline lay with Porter, for the glossary with Kiger. However, the strategy of the whole, by which the outline and glossary were coordinated both logically and functionally, was a joint product. Its execution required frequent mutual attention to fine detail, and each of us fully concurred with the other's ultimate decisions, sometimes reached only after much debate. Certainly, the glossary was not then, and still is not now, exhaustive, but we believe that in its present state it does cover a very high proportion of the total complement of structures, characters, and character states pertinent to detailed conventional description of the morphology and higher-level anatomy of plants other than algae.

Because we have consciously sought to eliminate pointless redundancy, this work is not a comprehensive dictionary of existing terminology nor a guide to all the varied, often idiosyncratic modes of descriptive expression. We have not hesitated to exclude, supplement, or modify elements of existing usage when logic and/or practicality so dictated, failing which the main object of the work would have been seriously compromised.

We urge users to suggest additions or modifications that may be appropriate for a future revision. Despite extensive "fine tuning" since it appeared in provisional form, the work surely is not perfect, and we welcome constructive criticism—that based on logical analysis, not merely uncritical dedication to parochial quirks or hoary tradition. Confronted with taxonomic chauvinism, we shall remain unmoved, having been at some pains to eliminate the unnecessary redundancies, ambiguities, and inconsistencies produced by that sort of allegiance. Our aim has been not to rigidify or sanctify, but rather to provide a more rigorous, logically consistent, and truly systematic, yet adaptively flexible, comprehensive framework for precise description of plants.


Many people associated with the Flora North America Program contributed in various ways to the evolution of the provisional edition, and thus to the present work. However, we are solely responsible for the content presented here, including any omissions or errors.

The morphological outline of the provisional edition was begun for the original FNA by John H. Thomas, and many of our basic ideas derive from his preliminary studies. John T. Mickel (ferns and "fern allies"), John J. Fay (Asteraceae), Frank W. Gould and Thomas R. Soderstrom (Poaceae), and Elbert L. Little (Pinophyta) provided extensive advice on their particular specialties. Robert W. Read and Lawrence E. Skog helped significantly with actual production of the preliminary version. Leo J. Hickey (leaf architecture), Richard H. Eyde (floral morphology), and Joan W. Nowicke (pollen) gave generous assistance with problems involving the structures, characters, and character states pertaining to their areas of special expertise.

The computer strategy for the original FNA was designed by Harriet R. Krauss, and the provisional edition of the outline and glossary would not have materialized without the contributions of our coauthor, Judith E. Honahan, who coordinated that strategy with our botanical design.

The other members of the original FNA Editorial Committee (John H. Beaman, Arthur Cronquist, Walter H. Lewis, John McNeill, John T. Mickel, Albert E. Radford, Peter H. Raven, Stanwyn G. Shetler, Roy L. Taylor, and John H. Thomas) and the other FNA Associate Editors (Orland J. Blanchard Jr., John J. Fay, Jerold L. Grashoff, Bruce MacBryde, Raymond J. Moore, Gary H. Morton, and Lawrence E. Skog) commented critically on drafts, both collectively and individually. Following the demise of original FNA, and after we had revised and expanded the outline and glossary, Lincoln Constance provided an extremely perceptive and valuable review of the entire scheme.

During the period since the inception of the current Flora of North America effort, drafts of the glossary adapted for use in that project have been reviewed in detail by John L. Strother and John W. Thieret, who made many helpful suggestions, and generally by other past and present members of the project's Editorial Committee.

We warmly thank all these colleagues, with special appreciation to Stanwyn G. Shetler, Program Director of the original FNA, for his varied and continuous assistance during that period of the work's genesis.

Major sources consulted in preparing the glossary include Martyn (1796), de Candolle (1844), Lindley (1847), Gray (1887), Jackson (1900), Moll (1934), Maheshwari (1950), G. H. M. Lawrence (1951, 1955), Smith (1955), Esau (1960, 1965), Eames (1961), Erdtman (1966), Rieger et al. (1968), Heusser (1971), Radford et al. (1972), Bold (1977), Hickey (1979), Lincoln et al. (1982), E. Lawrence (1989), and Stearn (1992).

We utilized all sources only as starting or reference points. The resulting product contains much for which no authority can be cited save our own analytical judgement. Indeed, the present work differs as much from the provisional outline as the latter did from its progenitors.


Plant taxonomists have been notoriously lax in their use of terms for morphological description, and glossaries are choked with synonyms, full and partial. Different terms often are applied to the same structure, character, or character state, and conversely, sometimes the same term is used for different things or conditions. The formatting of descriptions also leaves much to be desired, as few descriptions are truly comparable. We attempted to rectify this situation by compiling a coordinated outline and glossary to guide preparation of morphological descriptions for original FNA. The present glossary is a direct outgrowth, much amplified, from that initial effort, and the original outline of structures and characters to be described, while not presented explicitly here, is largely implicit in the organization of the present work.

In order that the glossary be more useful than others now available, we have attempted to define the terms unambiguously, while allowing for growth and revision as may be desirable. We have made no effort to take into account any but pragmatic reasons for including certain terms and not others; this is a practical work, not an exercise in evolutionary interpretation, and such implications are purposely excluded.

Original FNA sought to create and maintain a computer database of information on the vascular plants of North America north of Mexico. Contributing specialists and staff botanists would assemble data for each included taxon in a standard form suited to automated storage and retrieval. A prerequisite was that the traditional descriptive format and lexicon of vascular-plant taxonomy had to be reduced to a logically rigorous, internally consistent scheme—one that would be suited for machine storage, organization, manipulation, and representation of the data.

Although the initial product of original FNA was to have been a diagnostic manual of the flora, one similar to existing conventionally produced floras, the primary goal of the project was the formation of the database itself. This was to be a dynamic encyclopedia for North American vascular plants, one that would serve a great variety of both scientific and practical needs on a continuing basis. Its most important attribute was to be its capacity for meaningful comparison of data from one taxon to another by any categorical parameter(s). Such comparison is possible only when descriptions of taxa are strictly comparable (parallel) in format and coverage, and when they are terminologically consistent. Because floras are intended primarily as means for rapid and easy identification, their descriptions usually include only the most diagnostic characteristics of each taxon. But the characters (categories of characteristics) that are useful for diagnostic differentiation vary greatly among taxa. Consequently, the descriptions in any flora are rarely comparable from one family or genus to another, and often they are not comparable even among species of the same genus. In order to achieve such comparability, original FNA required a standardized outline of descriptands and a logically coordinated glossary of standardized descriptors. The provisional work from which the present one grew (Porter et al. 1973) represented a first approximation of such a scheme. After the demise of original FNA in early 1973, we continued refining the scheme, meanwhile adapting it for more general use, in either traditional or computerized applications. Still later, after the current FNA project became operational, we decided to present the glossary in a form tailored for use in that effort.


The hierarchical outline for describing plant morphology that we developed for original FNA, and that we subsequently expanded and refined, had eight levels. The first seven levels enumerated morphological entities, the eighth (lowest) specified the characters (attributes) that could be described for each entity, and the categories of character states (descriptors) in the coordinated glossary corresponded directly with the characters in the eighth level. As well, the glossary included definitions of all the terms designating the entities in the first seven levels of the outline, and of the terms designating the characters in the eighth level—that is, of all the descriptands.

The glossary in its present incarnation also includes both descriptands and descriptors. The records in the database include fields for: Term, Synonyms, Category, Limitation, and Definition. When a given term pertains to more than one category, each such application is represented by a separate record, and when the corresponding definitions are different, each distinct sense is indicated by an arabic numeral immediately following the term in each of the relevant records. Plural form(s), if irregular, and variant forms, if any, are also indicated in the Term field. Full, partial, and/or false synonymy is indicated in the Synonyms field. In the Category field, the relevant application is rendered in lower case if it is a category of descriptors, in upper case if a category of descriptands. Any restriction of the morphological scope of application, if not obvious from the context or definition, is indicated in the Limitation field. The Definition field includes the definition proper along with explanatory comments as appropriate.

A peculiar asymmetry in the structure of the glossary arises from the fact that traditionally some descriptands, notably plants, inflorescences, and fruits, may be described by either nominative or adjectival forms of descriptors—e.g., "plants shrubs" versus "plants fruticose," "inflorescences cymes" versus "inflorescences cymose," "fruits berries" versus "fruits baccate." In order to provide for the nominative option as well as the adjectival, we have included the former sets of terms in a category designated "nominative," the relevant descriptands being indicated as limitations of application.

Owing to the nature of existing terminology and usage, the matter of synonymy involves more than one-to-one correspondence in many cases. Terms may be only partially synonymous: their meanings may overlap; or the meaning of one may include but be broader than that of the other, but not vice versa. Sometimes terms that are not synonymous at all have been commonly and erroneously treated as such. In the glossary entries, full synonyms are given following an equal sign (=), separated by commas if more than one. Such a term is denotatively equivalent to and interchangeable with the entry term, though it may differ subtly in connotation because of different traditional contexts of use. Approximate synonyms are given following an approximately-equal sign (≈). Such a term is nearly equivalent to the entry term, but its denotation differs slightly in meaning and/or customary compass. Partially synonymous terms are given following a greater-than sign (>), when the meaning of the entry term includes the more restricted meaning of the synonym; or following a less-than sign (<), when the meaning of the entry term is included within the broader meaning of the synonym; or following both signs adjacent (><), when the meanings of the entry term and of the synonym overlap, neither fully including the other. False synonymy is indicated by the qualification "misapplied." All synonyms have their own full entries within the glossary, which thus is fully symmetrical as between entry terms and synonyms. We have indicated no preferences for the choice of some synonyms over others, except that we have qualified some terms as "not recommended," when they appear as either entry terms or synonyms, because they are vague or confusing (e.g., "bundle," "grain"), logically unsuited (e.g., "obsolete"), or botanically inappropriate (e.g., "dorsal," "nerve").

Throughout the glossary, terms such as "usually," "often," "sometimes," and "rarely" appear in definitions. These are used only in the sense of taxonomic occurrence—to indicate variation in some respect from one taxon to another. They are not used equivocally, but rather advisedly, and in the absence of clear indication to the contrary no sense of qualification within individual contexts of occurrence is intended. The term "generally" also is used, deliberately, throughout. In all cases, it connotes the sense of "overall" or "on the whole" rather than that of "usually." Thus, it is not meant to imply variation in any respect. Reference to essential, fundamental, or basic nature is expressed by the use of "essentially," "fundamentally," or "basically." These are used interchangeably throughout. The words "relative" and "relatively" also appear frequently in the definitions, always signifying comparison in the literal sense, the reference being definite, whether explicit or implicit. They are not merely equivocations or hedges, but rather indications of status relative to that in some other parallel context(s).


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