Dirt or water contamination in the microscope column interferes with the electron beam and reduces the quality of the image. This presents problems because the drying process causes shrinkage and can destroy the very things the botanist wishes to study. Most are dried through processes such as critical point drying or freeze drying.

In critical point drying the material is chemically fixed to preserve its living form. It is then gradually dehydrated by increasing concentrations of solvent to remove the water while minimising the risk of damage. It is placed in the critical point dryer and purged with liquid carbon dioxide to remove all traces of solvent. The sealed chamber is then heated to 31 degrees centigrade. The carbon dioxide can then be gradually vented without risk of surface damage.

Freeze drying causes less shrinkage than using a critical point dryer, but it takes longer before the specimens can be mounted.

Dry specimens are mounted on aluminum stubs and coated in metal using a sputter coater. Coating produces a conductive surface preventing the build up of negative charge which would otherwise cause image distortion. Coating also increases the secondary electron yield of the specimen thus improving the signal.

For botanists at the Royal Botanic Garden the scanning electron microscope provides an opportunity to study plant surface structure in minute detail. Factors such as the structures of pollen and seeds; the presence or absence of hairs or the appearance of leaf scales assist taxonomists in the identification and classification of plant species. The images included in this exhibition depict some of the characteristics studied and how microscopic structural differences may provide the taxonomist with valuable clues to species' classification.