Features Observed by Electron Microscopy as Generic Criteria

Abstract

Summary The advantages of greater resolution and depth of field provided by the scanning electron versus the light microscope have led to both a re‐evaluation of the usual microcharacters and discovery of novel ones not easily observed by other means. Comparative studies of SEM‐level characters in taxa of Compositae have shown that they are taxonomically useful, but that they are neither more nor less valuable as a means of generic delimitation than are macro‐ or micromorphological ones. As is true of taxonomic data from any source, it is the consistent occurrence of one or more SEM‐observed features as a part of a suite of correlated characters that provides sufficient information on which to base systematic decisions. Within this context, it is the newly discovered characters that prove most useful: the chance of finding correlated character suites rises with the number of characters observed. However, because the extent of infraspecific variation in these features has not been thoroughly explored, they should be employed with caution and in conjunction with numerous others in making taxonomic decisions at the generic (or any other) rank.

Micromorphological observation of seed coat of Eucalyptus species (Myrtaceae) using scanning electron microscopy technique

“…According to Barthlott (), the arrangement of epidermal cells usually has low taxonomic importance, apart from some families with high significance of particular type of cell arrangement for delimitation at genus or even up to species level. The confidence level of any characterization at certain taxonomic rank depends upon the consistency of character state taking place within or among taxa and their correlation with other characters (Lane, ). Seed morphological studies with the help of SEM can yield a wealth of information regarding ecological, evolutionary, and taxonomic insights.…”

“…Seed morphological characterization can solve some of the taxonomic confusions and can be successfully applied in the identification and classification of species (Hosny & Zareh, ). Micromorphological parameters provide sufficient information for systematic decisions due to their consistent presence (Lane, ). In some earlier studies, in the epidermal structure of some seeds considerable surface deformation, puckering of anticlinal wall and loss of typical cell shape have greatly been influenced with modification during desiccation (Moret, Couderc, Bari, & Delarue, ).…”