Plant Identification

by Anna Lawrence

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  For the place of publication of names of vascular plants, whether synonyms or accepted ones, users can consult Index Kewensis or, on the internet, the International Plant Names Index (www.ipni.org/). These sources exclude infra-specific taxa and (Index Kewensis) ferns and their allies, and most frustratingly do not mention synonymy.

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  Type specimens are often not very accessible; but there is an increasing number of

  ‘virtual herbaria’ with detailed images of type specimens on the internet. Search for

  ‘type, specimens, virtual, herbarium’ on the internet to find the ones relevant to you.

  New species have to be named in a way that distinguishes them reliably from all other plants in the world, and for this reason taxonomists tend to focus most strongly on fertile characters (see Box 4.4). The fact that fertile characters are not always available in plants met in the field contributes to a continuing demand for field guides:

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  As your field guide will probably cover a limited area, you do not need to distinguish your species from all its close relatives in the rest of the world, so small fertile characters are usually not as important as they are in a monograph or Flora. Species

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  BOX 4.4 VEGETATIVE AND FERTILE CHARACTERS,

  AND STERILE SPECIMENS

  Flower- and fruit-related details are sometimes called fertile characters, in contrast to vegetative characters of leaf, stems, roots and general plant form. A specimen with only vegetative features is a sterile specimen. Vegetative characters usually vary more with climate and geography than fertile characters. For instance, a single species may have small leathery leaves when growing on mountain tops and larger, papery leaves when in the lowlands: fertile characters, like the hairs on stamens or petal length, usually vary less.

  Therefore, although some species are formally distinguished by vegetative features alone, taxonomists tend to emphasize fertile characters when species are first described.

  However, vegetative characteristics, such as leaf size, may be more obvious and useful differences between two species, and can be just as reliable if a field guide is very localized

  – for example, for one forest. The bias towards fertile details in new species descriptions tends to be carried through into the keys and descriptions of Floras and monographs, in general; but this is a bias that a field guide writer should not follow uncritically.

  rediscovered in the field often have surprisingly distinctive, but unrecorded, features

  – such as long plank buttresses or a strong smell – which the author of the name was unaware of in the herbarium.

  Common, scientific or both names in your field guide?

  Common names have many obvious advantages over scientific names: they are mostly memorable, often short and in tune with local patterns of speech and cultural association, hence local user friendly. They frequently out-survive the appropriate scientific names, which as we have seen can change overnight. So why should we not have a strong bias towards preferring such common names in field guides? Apart from the usual problems of names cited above, which are more serious than for the scientific equivalents, there are at least three over-riding reasons for using scientific names in addition to the common ones:

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  Science is global, and its nomenclature strives to be globally applicable, so its names are the keys to information available globally about the plants.

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  There is a continuous coordinated effort to improve and standardize scientific nomenclature; so any ambiguity is generally very limited compared to local names.

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  Scientific names do go out of use; but the old and alternative Latin names are documented rigorously, so it should be possible to translate any unused Latin name to the one (at worst, a few) name that is valid today.

  Field guides should therefore include at least a cross-reference to the plants’ scientific names, even if the aim of the guide is to show the plants in the context of a local community. This is for the same reason that books in libraries should have a global standard ISBN code number, as well as their title – these are universal, standard codes that allow published books to be catalogued and looked up regardless of the language.

  Your guide will be of more interest and use to people from various cultures if you mention the scientific names, as well as the most appropriate common names. However,

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  if it is to be used in a limited area it will obviously mean more to users, and will certainly be more culturally sensitive, if local names are there as well, even if they are ambiguous.

  If your guide in any way promotes local conservation or ethnobotanical interests, then you should mention both common and scientific names:

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  As a rule of thumb, include both scientific and common names, but consult with users and other key informants as explained in Chapter 3 to define which common names to use, and which to emphasize on the page.

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  Encourage your users to invent a plausible common name for species that have not been previously recognized (say where you have done so, to keep linguists happy), as the production of a field guide provides a rare chance to fix or standardize such names in the vernacular. Where one name covers several species, consider inventing qualifiers in the language of the existing common name to specify them – for example, like small asanfena and black mahogany.

  Referring to scientific names in field guides

  Although the Latin binomial is essential if you are referring to species names, there are some optional extras to the name.

  Authors

  Names in Floras and monographs always include the authors (see Box 4.2): should you include authors in your field guide? Although the cautious answer is yes, there are circumstances where they may be excluded without a problem, so explain their role to your users and see what they want. If the names can all be found in a Flora, it might make sense to save space by excluding them (as in field guides by Corner, 1988; Hawthorne, 1990; Ashton et al, 1997). On the other hand, it is a useful service to your readers to mention authors in the species index at the end of a book.

  Based on feedback from a few annoyed users of an earlier field guide (Hawthorne, 1990), where author names had been excluded for simplicity, author names have been included in a more comprehensive guide book (Hawthorne and Jongkind, 2006), particularly as the number of names altered since the Flora of West Tropical Africa (Hepper and Keay, 1954–1972) meant that the newer book will also function as a name reference list. Although directly useful in a small minority of cases, many users demand author names from field guides only because of a convention whereby journals demand these author names whenever a species is mentioned:

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  If in doubt, in a tourist guide where the names all refer to those in a standard Flora, a binomial is adequate. However, for all technical guides, include authors unless you can refer to a complete list of names in a previously published checklist or Flora.

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  You should not need to list authors more than once for a species: since they make the Latin names even more daunting to non-botanists, it is best to hide them in the species index, even using a smaller font.

  Infra-specific names?

  Infra-specific names are cumbersome, often representing only minor variants of plants, and very commonly for field guides only one such variant will occur in the region

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  anyway, so the infra-specific names add little information to your guide and will clutter up your pages. Infra-specific taxa are applied more inconsistently than species names, and some taxonomists ignore them altogether:

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  For simpler field guides, you may choose to ignore these names and you will still be scientifically correct.

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  On the other hand, even for simple guides you may find that there
are endemic infra-specific taxa, found only in your area: this is the sort of attribute that many users find interesting and conservationists demand. If you have such cases, include the names and all other infra-specific names as well to be consistent. Ask your users whether they think the names are useful; but where there is uncertainty, include infra-specific taxa in more technical guides.

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  If including infra-specific names, where only one infra-specific taxon occurs in your area, it is helpful to put the infra-specific part in brackets – for example, Antiaris toxicaria (subsp. toxicaria), to show that for your area all infra-specific taxa belong to this subspecies. When there are two or more infra-specific names for one species in your area, leave the brackets out to emphasize that there is more than one valid option.

  Be critical if you know your plants well and if the names available for the plants that you have to deal with in your guide do not do the variation justice. Scientific nomenclature is a work in progress, not engraved permanently in tablets of stone. You might even be driven to do the necessary weeks or months of work required to describe a new variety or species yourself (Winston, 1999). However, if you are not experienced, find a friendly taxonomist to help you. You will need to become familiar with the contents of a large national or regional herbarium:

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  Accept that the same name may well be applied to a plant 2000 miles away that does not look like yours, and perhaps mention this trend in your descriptive text; you do not always need names to describe variation.

  Synonyms and why you need to know about them

  It often becomes apparent, maybe during the preparation of your field guide, that two published names represent only one species. The newer name should then be discarded: it becomes a ‘synonym’ of the older (see Box 4.5).

  There is a simple format for publishing a synonym, basically stating that name B is a synonym of name A, with few other details required. Many authors give little or no justification when publishing a synonym; but it is always helpful to explain nonetheless.

  You can publish a synonym validly in your field guide; but you should then summarize all proposed changes in one place in the introduction or index. If your guide will not be widely dispersed, it is far better to publish your synonyms before the guide is published (along with any new species) in a peer-reviewed journal. Other botanists are more likely to follow your decision on synonymy if you do so.

  Experts of local flora often feel robbed when monographers dismissively sweep their local endemic plant away as a synonym, when it is said to be ‘insignificantly’ different from its relatives. If you feel strongly that such a mistake has been made, and you have done the required research to support your notion, you could:

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  BOX 4.5 SYNONYMS AND WHY SCIENTIFIC NAMES KEEP CHANGING

  Independent taxonomists in different countries may be unaware of each other’s publications and give different names to obviously identical plants (see Case study 4.3). Another reason for synonymy applies when, as time goes by and new names are invented for all variants of a range of plants, it becomes harder to work out to which of these species a new specimen belongs. Perhaps it has the fruit shape of species X and the petal shape of species Y. It may become increasingly obvious that all combinations of fruit and petal shape occur, like height and ear length in dogs. Maybe the flower size, so different in two type specimens, is eventually seen to increase gradually across the continent, with no single obvious place to divide the spectrum. One species name should now be used for all such plants, and the oldest name is then employed for all. All of the other names become redundant synonyms. In these cases, the species epithet will normally change; the genus part stays the same. For instance, Napoleonaea leonensis became a synonym of Napoleonaea vogelii when it was realized that intermediates existed. The placing of a name in synonymy represents a matter of opinion, and you are not obliged to stop using names once they have been published as synonyms if you are well informed and do not agree.

  In other cases, two genera may be merged, or a genus may be split into parts, usually because a taxonomist has revised all of the species and decided that this describes the variation pattern most realistically. In these cases, the old genus name is retained for some species, and new ones are brought into use for the others. When a name changes in these circumstances, the genus part will differ between synonyms; yet the species part usually stays the same (maybe with slight changes to the ending to match the gender of the genus name). For instance, Aningeria altissima becomes a synonym of Pouteria altissima (see Case study 4.2) when it was decided that African Aningeria species fell within the range of variation of American Pouteria species.

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  ignore the changes and keep using the synonym; but show that you are aware of the proposed name change and give good reasons for ignoring it, otherwise your readers may simply think you have overlooked the publication;

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  formally publish the synonym name as a subspecies, variety or forma (a less diver-gent form than a variety or subspecies) in the new species.

  However, the easiest solution might be to:

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  identify your ‘lost’ plant with an informal or vernacular name in inverted commas in your field guide, alongside the proper species name, with a footnote explaining your reasons.

  In this case, explain that taxonomists are to ignore these informal names. This will let users know both the globally accepted name and that you are referring to some minor local variant of it.

  You should not, however, ignore new names just because they are unfamiliar or because your users prefer the old name. Taxonomists will usually have a better picture of the global variation pattern of the species than field guide writers, and you will not be doing your readers any favours by supplying them with names that the rest of the world will soon no longer recognize:

  72 Plant Identification

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  On the minority of occasions when a taxonomist fortunately happens to have revised the names of one of your groups of plants, it would be churlish of you not to follow to the letter their generally careful and well-researched changes. Unless you have a very strong reason, you should follow the global expert’s opinion, not your own local perception. However, if the local Flora is quite recently published, so there are only a few minor changes to its names, and you want to keep the taxonomic content of your guide simple, then it is reasonable in a technically modest field guide to follow the Flora’s names for all species and to state that this is your sole source, in effect ignoring any subsequent taxonomic changes.

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  Decide whether you want your field guide just to provide ‘field support’ to any local Flora, or if you rather want it to provide added value by bringing the taxonomy up to date. If the Flora is old (say, more than 20 years since publication), then be prepared to follow the latter route or your guide will look sadly dated from the moment it is published.

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  If you have chosen to update a Flora (or checklist), include synonyms defined since its publication. Include also any other names recorded erroneously in your area in the Flora, based on specimens now allocated a different name, with a brief note to indicate the error. In addition, list in your index the synonyms that are widely used in (pre-Flora) textbooks, even if the Flora already has listed them as redundant. In all of these cases, the redundant index entry should cross-reference to the correct name. Any justification should then be included, maybe as a short footnote or endnote – for example, entries for redundant names in the index:

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  Morus newsp L., p20

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  Morus oldsp Jacq, see Morus newsp

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  Then, a footnote entry on page 20:

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  Morus oldsp was recorded in our area in the Flora; but this was based on specimen Fred 23, which is, in fact, Morus newsp L. (see Bloggs et al, 2003).

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&n
bsp; It is worth looking up original descriptions of disused and long-forgotten synonyms, particularly if the type specimen of that synonym was from your area. Older species names, which are the ones most likely to be in use, generally have less descriptive text and illustrations than more recently published synonyms, and there might be information in the synonym’s publication that is more pertinent to your specific area than the more general description in any Flora or monograph allows.

  THE SPECTRUM OF BOTANICAL LITERATURE

  Taxonomic monographs and revisions:

  ‘Spring-cleaning’ in taxonomy

  Periodically, taxonomists review all of the species that have been created in a genus or other group of related species, together with the new specimens collected since publication, and publish a synoptic paper. At its simplest, this is a ‘revision’ that may appear in botanical journals: revisions themselves often include new species names as a sort of conclusion of the work. With a larger amount of study and background information, a complete book about a particular group may be published, which is then normally referred to as a monograph.

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  The checklist–Flora–field guide spectrum

  Botanists identifying new specimens in herbaria often follow opinions of earlier experts recorded on the original specimen label or preferably on the most recent determination slip (a ‘det. slip’ is a small label on which a specialist simply records their identification of a specimen), rather than relying on original descriptions; but when new species are recorded in an area, botanists must rely on the literature. Various types of publication exist to help a region develop a more consistent application of scientific names than is possible with many people independently working with type specimens and original descriptions, or copying earlier determinations for similar specimens in herbaria.

  Revisions and monographs summarize all plants described of a particular genus, family or other plant group. For more practical use in a particular region, synopses are made of all the available monographs and other publications for all families of plants (usually restricted to a very broad set of plant families such as ‘trees’, ‘flowering plants’ or