The silica in phytoliths has a refractive index ranging from 1.41 to 1.47, and a specific gravity from 1.5 to 2.3.
Scanning electron microscopy may also allow for a more detailed study of phytoliths.
Taxonomic resolution issues deriving from the multiplicity and redundancy problems can be dealt with by integrating phytolith analysis with other areas, such as micromorphology and morphometric approaches used in soil analysis.
Experimental studies have shown that the silicon dioxide in phytoliths may help to alleviate the damaging effects of toxic heavy metals, such as aluminum.
Finally, calcium oxalates serve as a reserve of carbon dioxide.
Phytoliths (from Greek, "plant stone") are rigid, microscopic structures made of silica, found in some plant tissues and persisting after the decay of the plant.
These plants take up silica from the soil, whereupon it is deposited within different intracellular and extracellular structures of the plant. Although some use "phytolith" to refer to all mineral secretions by plants, it more commonly refers to siliceous plant remains.
After processing, microscopy is used to identify the phytoliths.
Optical microscopes with magnifications of 200-400x are typically used to screen phytoliths.
Cacti use these as a reserve for photosynthesis during the day when they close their pores to avoid water loss; baobabs use this property to make their trunks more flame-resistant.
According to Dolores Piperno, an expert in the field of phytolith analysis, there have been four important stages of phytolith research throughout history.
By an unknown mechanism, which appears to be linked to genetics and metabolism, some of the silica is then laid down in the plant as silicon dioxide.