Introduction to existing field guides

Our online bibliography contains over 800 entries, but is far from exhaustive as there are many excellent locally produced guides that never reach botanical libraries in the UK. However, it does provide a strong indication of the sparse coverage of field guides in the tropics and current trends in field guide production.

There have been a few published reviews of field guides, from various perspectives. Frodin (2002) includes some major checklists and field guides. Guides to woody plants in the tropics, including field guides, monographs, revisions and ecological papers, are reviewed by  Rejmánek & Brewer Vegetative identification of tropical woody plants: state of the art and annotated bibliography (2001).

Schmidt (1999 & supplement) also provides literature references to some of the better-known tropical field guides, slightly biased towards North America and including animal and mineral guides. 

On this page, the wide range of field guides (the field guide spectrum) are subdivided into frankly rather vague categories as follows:

After this subdivision, there is an overview of Geographical coverage of field guides

The field guide spectrum

A plant field guide is a book, or maybe other portable 'device', that informs about plants in the field by facilitating identification of, and usually supplying subsidiary information about, a particular group of plants (e.g. 'trees') formal definition. "In the field" means in life, e.g. living plants in the forest or in the park. Most have many of the following properties or ingredients:

  • Less formal in a taxonomic sense than monographs, revisions, floras and checklists. No or few specimen citations
  • Portable, and suitable for field work.
  • Identification keys or other access methods, and/or descriptions and/or illustrations
  • Glossary to explain any jargon without referring to other books.
  • Emphasis on vegetative characters
However, we do not mean to be over-prescriptive, and wish to emphasise that the term is used for books with a particular 'niche' or position in the spectrum of botanical literature. Hence, field guides range from fact-filled, comprehensive and largely desk-bound books, half-way to Floras and called 'pragmatic floras' here, to popular, pocket-sized cheap and even potentially disposable guides with more emphasis on pretty illustrations than on identification accuracy. Botanists typically use various types of guide, depending on circumstances and opportunity.

The more technical and detailed field guides tend to be significantly more accurate than the less technical types, when used correctly.  However, less technical guides are often usable by a wider range of people, and usually have a primary purpose other than accuracy – perhaps earning money from sales or stimulation of interest. Therefore, it may well be the case that more plants end up being correctly named by more people with less technical guides.

 

Although early field guides were usually herbals, biased towards medicinal plants, over the last century tropical guide development has been driven more by a need for accurate tree identification for commercial forestry, and more recently for biodiversity inventories, environmental impact assessments, long-term ecological studies and eco-tourists. The demand for comprehensive tropical field guides is stronger than ever and the proliferation of popular field guides in Europe and America has shown tropical botanists what is possible, even if publishers are not over-excited by the market for such guide books in the tropics.

 

Pragmatic or 'field floras’ and similar detailed, technical field guides

Pragmatic Floras are identification guides for use in both the field and herbarium, more field-usable than true Floras, but with emphasis on accurate identification over portability when compared with other field guides. Most of the more recent ones help users to identify without flowers and fruits, bridging flora-level treatments and simpler field guides, if a Flora exists at all for the region, otherwise they substitute for them.

The target users are often botanists or other scientists, professional or amateur, and others working in forestry, conservation and related spheres  with a serious interest in plant identification. They support inventories and technical field work, are useful in both national herbaria and state agricultural or forestry offices, and act as key references for resource-related NGOs. An ecotourist would have to be unusually enthusiastic to consider buying one.

In most of the world’s biodiverse regions one cannot expect all unknown plants to be identified immediately in the field, even with the best field guide or Flora, if the names are to be accurate. Identification of difficult plants in the forest can rarely be definitive if it is to be quick and hurried. Specimens, inevitably often sterile, should be collected for the difficult plants. In these circumstances, field guides are most useful when they not only help identify plants in the field, but also help with the identity of sterile specimens in the herbarium or camp. This is a part of the niche of the extreme type of field guide we call a pragmatic Flora.

The repeated cycle of field then herbarium work is the best way to learn tropical botany, so by helping with both aspects of the work, these guides foster a deeper knowledge of plants in those with a serious interest. Pragmatic Floras have the following features:

  • Complete coverage of a broad plant type–often trees (in ‘Tree Floras’) or higher plants
  • They often cover a region of several countries, or at least a whole country or large sub-region.
  • Typically 500-3000 species
  • Taxonomically correct, but they concentrate on information necessary for identification. Some list synonyms.
  • Characters described are generally consistent across species, and fairly comprehensive for all basic morphological details.
  • Modern versions are well illustrated, for up to 100% of species.
  • They are useful, like a Flora, as a general plant name dictionary
  • They help production of simpler field guides by botanists or others: they are a source-book of field characters for such projects
  • Some botanical competence is assumed of the user; but they form an excellent foundation for an individual’s long term botanical education
  • Typically 2 -10 years to produce, for one or more people (often as a background job whilst doing other work); some take even longer. They are mostly made by experienced botanists with access to herbarium collections and taxonomic literature, but their production requires considerable fieldwork.

Slimmer, technical field guides

Over  the last fifty years, a vague trend can be seen from text-rich, less illustrated (Burtt, 1953, an unillustrated key for field use) or heavy ‘Tree Floras’ to slimmer and friendlier guides, often with a greater range of plants and greater use of illustration. With the facility of adding colour photographs , a new wave is breaking, where illustrations dominate, but where efforts have to be made to keep the book portable. The larger Pragmatic Floras are inconvenient for field use, even if the library allows them out. In order to reduce the weight and the amount of work required to make technical guides, but maintain the accuracy for those taxa that are covered, there are five main options:
  • Only deal with species of a particular (presumably problematic and important) narrow taxonomic group– the field monograph
  • Limit the information per species – slimmer, but all-species guides for many families –as in some concise, technical guides.
  • Limit the geographic area of interest – as in other concise, technical guides
  • Reduce the taxonomic resolution – Generic guides (e.g. genus level, often with short notes on some species)
  • Deal only with a subset of the species from many families – Incomplete set guides
  • .

By reducing the burden of information in all these ways at once, it is possible to make a very light field guide! These are then so lacking information that they will rarely be accurate, and with limited coverage such guides rarely aspire to high technical standards. On the other hand, they may serve other functions, as the following examples show.

Light and airy Guides: non-technical, often glossy & superficial

There are many guides of this type mostly with limited distribution. They are relatively quick to make, and usually introductory, for tourists or publicity, perhaps aimed at telling short-term visitors (e.g. day-trippers) something of interest for a small area of vegetation. In these circumstances, not all species need to be identified– often only the most obvious species are included. Species level accuracy is not crucial, whereas trivia, general interest and beauty are prime attributes. Often such guides include a diverse range of non-botanical information, and may include sections on animal life, history, geology or other subjects.

These texts in turn can be subdivided by degree of seriousness expected of readers – and they will often be casual readers rather than serious users (compare Seddon & Lennox (1980), Lack et al. (1998), Hawthorne et al, (2005) all aimed at Caribbean tourists, but with varied information content, the latter two verging on a slimmer type of technical field guide with coverage of all woody plants in the area specified).

Although the previous types should be eminently useable in schools, school-level texts, must be cheap, generalised but possibly usable in some cases on trips to a forest. It is helpful if examples can be made of widespread and common species, to facilitate utility in many areas. Very often, these include technical diagrams of various plant families. These can barely be considered general field guides, except those mentioned above  but are rather school class notes. Some material appropriate for schools also falls under the next heading.

 

Laminated Card and modular Guides

In recent years various guides have been published with pictures, often photographs or paintings, on a single laminated sheet of card. Some are laminated by more than a standard office laminator, more like credit cards, and can then even be used underwater. Cheaper ones become yellow or frayed at the edges over years of use. Schmidt (1999) lists many such cards covering mostly north American plants, pond life, birds, fish and so on. Although all sets deal with rather narrow groups of species, in often-limited areas, they can be recombined with other sets to extend the range. There are two main design approaches:
  • One approach is to arrange several species on a card according to themes, sometimes with text, or more pictures on the back. This approach is taken in the Chicago Field Museum ‘Rapid Color Guide’ cards, two sided laminated sheets with 20 species per side, often many cards per theme aimed mainly at researchers. Another highly user friendly and attractive type of laminated card guide, some of which fold out, are produced by the U.K. Field Studies council, each on one theme are aimed at schoolchildren or experts.
  • Another approach is to produce one card per species, such as the 67 species guide to aquatic plants, held together with a metal post, by Ramey (1995). This type of format apparently has untapped potential for biodiversity problems, and is the type investigated by us for Ghanaian trees.

A set of laminated cards covering the same species as a typical field guide need be no different in information content. Their main innovation is in the Access Method (See Modular guides).

Electronic Guides

Electronic media are fundamentally and positively affecting the manner of publication of some botanical information, both in terms of  interactive internet guides, including self-assembly field guides that can be printed for field use, based on the species and information you want in your guide, and applications with multi-access keys, potentially self-published on the internet.

 

Geographical coverage

We cannot estimate the proportion of the tropical flora covered by field guides directly, as the overlap between guides cannot be calculated without collating species. However, even though different regions could on average have higher numbers of species per guide, the ratio of species to guides in our database gives some indication of the regions that are most sparsely covered. These are the three regions of highest biodiversity, Colombia-Brazil, Central Africa and Indonesia, which also correspond to the main areas identified by Frodin (2001) as priorities for floristic work. They all have either no floras or very incomplete floras that have virtually stopped production.

Region/country No. of species No. of field guides Species/Guides
South America 98,800 122 800:1
  - Colombia-Brazil 70,000 44 1590:1
Central America 7,380 67 110:1
Southern Africa 23,000 72 320:1
West Africa 10,340 46 225:1
Central Africa 16,320 28 580:1
  - Cameroon 8,000 4 2000:1
  - Zaire 11,000 7 1570:1
East Africa 7,850 39 200:1
Madagascar 12,000 6 2000:1
Tropical Asia 79,500 138 580:1
  - Indonesia 20,000 8 2,500:1
Australia 25,000 50 500:1

Species totals are taken from Bramwell D., 2002. How many species are there? Plant Talk 28.

 

A Selection of field guides to flowering plants and conifers

Field guide development in the tropics has been largely driven over the last 70 years or so by a need for accurate tree identification by forest managers. Increasing demands on forest resources, a declining pool of expertise and growing identification needs for rapid inventories, environmental impact assessments and long-term ecological studies have increased the momentum over the last 20 years. An important influence has been the proliferation of popular guides to the plants and animals in Europe and America; tropical botanists have seen what is possible. Modern field guides are evolving to have less text and a primary emphasis on illustrations. Improvements in imaging and printing technologies over the last few years have helped to speed production and raise the quality of books.

Read a summary review »

Pteridophytes

The Pteridophytes are defined in the broadest sense to include the true ferns, Filicopsida, and fern allies, Lycopsida (Lycopodiaceae, Selaginaceae and Isoetaceae) and Equisetopsida (Equisetaceae). They are generally well covered in the floras, but there are few good tropical field guides and the list of useful models below consists mainly of temperate guides.

In some ways the ferns and allies present less of a challenge than the seed plants for field guide authors. Fern fronds, pinnae and sori are essentially two dimensional, and apart from illustrating habits and whole fronds, many useful images can be captured in the herbarium using digital photography or desktop scanning. Some guides resort to spore characters, but for most species the frond shape and details of the pinnae and sori should suffice. The shape of the indusium (the protective membrane around the sporangia), if present, is diagnostic for each genus.

Taxonomists often use spore characters for delimiting taxa, and the spores of most species are too small to provide many useful field characters. A good quality field microscope, or even a hand lens with the larger spores, should reveal some gross morphological features, such as the shape and the presence of large ridges. The finer detail that separates many taxa requires a research-grade light microscope. Anyone considering using spores for identification should consult Large & Braggins (1991) for a useful discussion of methods and an example of a key based on light microscope observations. They illustrate all species with images from both light and scanning electron microscopes, but the latter provide the clearest, most detailed and fully 3-dimensional images. Tryon & Lugardon (1990) is a reference work surveying the spores of 232 genera in 35 families, with scanning and transmission electron micrographs illustrating all genera and showing a range of species for the larger genera, e.g. Asplenium (73) and Selaginella (87).

Read a summary review »