Guidelines

The aim of this book is to provide a fully illustrated terminology and glossary of the most important palynological terms, including a substantial standardization of definitions. If terms are not considered here, then they appeared to us as insignificant, or they belong to the terminology of fern spores, which is not considered here. A comprehensive description of pollen grains with terms mentioned in "Pollen Terminology. An illustrated Handbook" is easily accomplishable.

A strict rationalization of terms on the basis of practical criteria has been attempted. For consistency, phrases are standardized as far as possible; for example, features of ornamentation are stereotypically defined as "pollen wall with ", and pollen wall features (or pollen shape and size) as "pollen grain with ".

Where it was necessary, definitions have been reworded, newly circumscribed, or brought into focus. In addition, consistent application of EM techniques and the nowadays better understanding of pollen features have made redefinition of some terms necessary. Moreover, we have classified terms according to applied techniques (LM, SEM, TEM) and their usage in morphological, anatomical and/or functional context. In chapter "Alphabetic Glossary" the entries are arranged alphabetically. The definitions are provided with numbers in bold referring to the respective page in chapter "Illustrated Glossary"1 and numbers in square brackets referring to important literature (see chapter "Bibliography").

Emphasis is given to the numerous illustrations. The worldwide largest database on pollen, PalDat (http://www.paldat.org/) is the main source of pictures. Each term is illustrated with LM or EM pictures in order to point out the character range of a term (or,

' Please note: literature references are not necessarily the earliest publication in which the term was used. The comprehensive literature list (see chapter "Bibliography") includes beside the references more and other (and preferably recent) publications which have been selected as sources of further information.

more precisely, to show the full range of a single character). Brief information on the method of preparation is often provided. In preparing pollen for SEM micrographs, acetolysis was avoided as far as possible.

Underrated pollen conditions, e.g., the physical condition of the turgescent, life-like pollen, are considered. The SEM micrographs usually represent the turgescent condition, without further notice. Consequently, pollen grains are often shown in dehydrated stage, marked as "dry pollen". The deviating characters in turgescent and dry pollen grains are designated by descriptive pictorial terms such as cup-shaped, boat-shaped and aperture sunken.

Comments are provided where this may help in the application of a term or to qualify the circumstances in which it is used.

Self-explanatory general terms are usually not defined; in such cases the context is noted (e.g., circular, see outline). For more information on these see the appropriate page(s) in chapter "Illustrated Glossary".

Three categories of terms are used: important terms are printed in bold and are usually illustrated; terms of minor importance are printed in regular script, usually without illustrations (if necessary, terms in chapter "Alphabetic Glossary" are sometimes also illustrated in a footnote); terms printed in italics are not recommended and often provided with an explanatory comment.

The chapter "Illustrated Glossary" is subdivided into larger topics, e.g., "Shape and Size" or "Ornamentation". The terms themselves are listed according to their resemblance in order to provide the user with a side-by-side spectrum of similar characters. For a quick orientation please use the last page of "Pollen Terminology. An illustrated Handbook". It is a fold-out page with terms alphabetically arranged. Numbers indicate the page in chapter "Illustrated Glossary".

In contrast to chapter "Illustrated Glossary" the terms in chapter "Alphabetic Glossary" are throughout arranged alphabetically as the noun and the corresponding adjectival form, if appropriate. Few terms are used exclusively as nouns or exclusively as adjectives. Sometimes two adjectival variants (-ate, -ar) are used but, if so, in two different meanings. For example: from the noun granulum (sculptural or structural element of differing size and shape, less than 1 |jm in diameter) derive the two adjectival forms granular and granulate (both meaning "with granules"); these are corresponding terms used in two quite different contexts: granular describes a distinct type of infra-tectum hence a structural feature whereas granulate refers to an ornamentation feature - a sculpturing element.

Both the singular and the plural are given consistently for Latin terms. The English spelling of the Latin term is added (porus, pl. pori, engl. pore) if the English form is preferable.

Cross-references are given to terms that are synonyms (the preferable one is printed in bold) or that indicate the opposite condition (antonyms), e.g., homo- and heterobrochate.

Numbered literature references are given for each term in chapter "Alphabetic Glossary" and are not necessarily the earliest publication in which the term was used.

PUNT et al. (2007) provide the basis of the present terminology. Many terms in palynology were coined at a time when only LM observations were available. Mainly for historical reasons, inconsequent nomen-clatural applications, enumerations of synonyms, and even differing definitions have been found for one and the same term.

During the 20th century questions of terminology became more and more problematic. The main reasons were the greatly increasing number of publications in palynology, dealing with sometimes insufficiently described or "uncommon" pollen features, and simultaneously the advent of manifold applied fields of palynology. For various reasons, nearly all authors used their own terminology. The situation became worse in the 1970s and 1980s, leading to a variety of terminological "schools".

Nonetheless, in the 1950s attempts were made to restrict the wording and to state the definitions of terms more precisely. A deserving, widely accepted but all-too restricted list of pollen morphological terms and definitions was published as early as 1950 by IVERSEN and TROELS-SMITH. Later, KREMP (1968), in his famous encyclopedia, provided a monumental enumeration of all known terms .

Being aware of the danger that pollen terminology tends to become foggy, REITSMA (1970) took the first resolute step to overcome this problem. A concise terminology now became available, though unfortunately not taking account of the range of variation of most of the palynological features, and without drawings or micrographs. F^GRI and IVERSEN (1989, 4th ed.) restricted their glossary to terms exclusively used in their book. MOORE et al. (1991, 2nd ed.) provided a glossary of selected terms used in their pollen and spore keys. Standardization came with the glossary by PUNT et al. (1994), updated in 2007. The main advance of their concise and comprehensive terminology is the consistent usage of drawings and the critical comments on terms and usage.

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