Crystal idioblasts in plant vacuoles made of calcium oxalate are structures that have long been studied by plant biologists. These structures are formed by the reaction of calcium and oxalate ions in high concentrations, and can be found in various shapes and sizes, including prisms, druses, raphides, and crystal sand. They are found in different tissues of plants, including leaves, stems, roots, and fruits, and are believed to play a role in plant defense against herbivores and pathogens.
One particular genus of plant that is known to have crystal idioblasts is Houttuynia. Houttuynia cordata, also known as the chameleon plant, is a herbaceous perennial that is native to Southeast Asia. The plant is known for its medicinal properties and has been used in traditional Chinese medicine for centuries. It is also grown as a garden plant in some areas.
Houttuynia cordata has unique crystal idioblasts that are shaped like long needles. These needles are arranged in a specific pattern, which gives the leaves of the plant a shiny appearance, similar to that of iridescence or the sparkle you see in gemstones. The crystal needles reflect and refract light in different directions which crests a shimmering effect. This effect is most prominent in the leaves of the plant, which have a heart-shaped appearance and are green with red veins. However the effect can also be seen in the stems easily as well.
The unique crystal idioblasts of Houttuynia cordata have obviously attracted the attention of researchers and collectors. Studies have shown that the crystals have antimicrobial properties and can inhibit the growth of certain bacteria and fungi. The plant has also been studied for its potential use as a natural dye, due to the presence of flavonoids in its leaves.
In addition to Houttuynia cordata, other plant species such as Begonia pavonina and Begonia prismatocarpa are also known for their iridescence caused by the arrangement of calcium oxalate crystals in the vacuoles of crystal idioblasts. These plants have elongated crystals with a hexagonal cross-section, which creates a periodic arrangement when packed together in the vacuole. This periodic arrangement creates a diffraction grating, which reflects and refracts light in a specific pattern not too far off from the sparkle in your favorite ring. The color of the iridescence depends on the angle of light incidence and the orientation of the crystal needles.
The phenomenon of iridescence in plants has not only attracted the attention of plant biologists and horticulturists, but also the interest of materials scientists. The structural color produced by crystal idioblasts has been used in the development of artificial structural colors.
Overval it’s a pretty darn neat topic, and an even neater plant! And now you know.