ONLINE IMAGE COLLECTION

About the Image

About 75% of flowering plants produce calcium oxalate crystals in some or all of their organs. Because these crystals occur in various shapes and hydration states that are specific and consistent within each organ, they have been used periodically as an internal taxonomic character. Since crystals and their macropatterns are usually retained in the mature leaves and stems even after they die or drop off the plant, such information should be useful for identification purposes, possibly in forensics. Only a few studies have followed the development of the crystals into what is called a macropattern in a mature organ such as a leaf. Such a study can aid our understanding of how different crystals form and how they relate to their specific organ tissues. Shown here are large, prismatic crystals in cleared mesophyll cells of a pomegranate leaf, observed between crossed polarizers. The prismatic crystal nearest the center of the image has a central, nonpolarizing core, and two of the crystals display epitactic or surface crystals.

Development of the calcium oxalate crystal macropattern in pomegranate (Punica granatum, Punicaceae)