TAXONOMIC RESOLUTION

The taxonomic resolution reached by identifying fossil or subfossil microspores depends on the degree of differentiation of morphological characteristics within the individual tribes. Good light-microscopy equipment with phase contrast is essential for the exact identification of pollen grains. In some cases a scanning electron microscope can be useful, but it is not recommended for general use due to the difficulties in preparing single-pollen slides from fossil material. Up until a few years ago, some pollen types were only identifiable to the family level, e.g. Apiaceae, Asteraceae (Asteroideae und Cichorioideae), Chenopodiaceae, Cyperaceae, Poaceae and others. New pollen-morphological studies now make an identification of at least some genera within these families possible. On the basis of pollen morphology, identification to the generic level is possible for most pollen-types, in particular for the woody plant species important for vegetation history studies. In the case of genera with few or even only one species, it is often possible to infer the most probable species for example Carpinus (betulus), Fagus (sylvatica), Hedera (helix), Picea (abies) and others. The definate identification of single species from pollen-morphology alone is only possible in a few exceptional cases, for example Myriophyllum spicatum, Sanguisorba minor or Sanguisorba officinalis. Usually, only species-groups can be identified below generic level, these are named "types" after the corresponding subgenus- section- or series-name or after a characteristic species, as in Pinus Diploxylon, Pinus Haploxylon or Quercus robur-type (all of which are deciduous oaks). Some types include several genera that cannot be separated using pollen morphological methods, for example Aster-type (Gnaphalium, Senecio, Tussilago, Antennaria, Inula, Solidago, Bellis, Aster, Arnica, Erigeron, Carduus etc.) and Ostrya-type (Ostrya carpinifolia and Carpinus betulus).