Calcium Oxalate Phytolith from Lemonade Sumac (Rhus integrifolia) leaves
This crystal is from the leaves of Lemonade Sumac (Rhus integrifolia). These phytoliths were collected by digesting Lemonade Sumac leaves in sodium hypochlorite solution (Bleach). This was collected from a plant near Banning, California.
Transmitted Circular Polarized Light Illumination
2. Franceschi, Vincent R. and Harry T. Horner Jr., "Calcium oxalate crystals in plants", THE BOTANICAL REVIEW, vol. 46, No. 4, Oct-Dec 1980, pp. 361-427.
3. Piperno, Dolores R., PHYTOLITHS, AltaMira Press, 2006.
4. Rapp, George Jr. and Susan C. Mulholland (eds), PHYTOLITH SYSTEMATICS, Plenum Press, 1992.
5. Madella, M., A. Alexandre, and T Ball, "International Code for Phytolith nomenclature 1.0", ANNALS OF BOTANY, 2005,available on line at http://aob.oxfordjournals.org/cgi/reprint/mci172v1
6. http://en.wikipedia.org/wiki/Phytoliths
Definition/Function:
KINGDOM: Plantae UNRANKED: Angiosperms UNRANKED: Eudicots UNRANKED: Rosids ORDER: Sapindales FAMILY: Anacardiaceae GENUS: Rhus SPECIES: integrifolia
Calcium oxalate phytoliths of lemonade sumac are whewellite, CaC2O4-H2O. They commonly form in various rhomboid crystals.Significance in the Environment:
Calcareous phytoliths may remain intact as the plant degrades. When the plant containing calcium oxalate phytoliths is burned the phytoliths go through a series of chemical reactions. First they begin to loose the waters of hydration. That begins at about 120 degrees Celsius. Next, carbon monoxide is released and calcium carbonate begins to form on the surface of the crystal. That begins at a temperature of about 420 degrees Celsius. At this point the crystal generally still maintains its original shape. The crystal shows the effect of the exposure to heat but the shape is still consistent with that characteristic of the original plant. Continued heating ultimately result in the formation of a calcium oxide, begining at about 620 Celsius. Cubical calcium oxide and hydroxide particles are common in the plume from the combustion of wood, often showing surface modification to the carbonate. The surface modification is evident as a birefringent film over part of the particle.Characteristic Features:
Whewellite is monoclinic with a beta angle of 107 degrees. The ratio of the cell parameters is 0.862 : 1 : 1.371, a:b:c. "b" = 7.29 Angstroms. The refractive indices are 1.490, 1.553, and 1.650 for a birefringence of 0.160. Whewellite is optically positive with a 2V of about 84 degrees.
Associated Particles:
References:
1. Blinnikov, Mikhail, "Phytoliths in plants and soils of the interior Pacific Northwest, USA", REVIEW OF PALAEOBOTANY & PALYNOLOGY, vol. 135, pp. 71-98, 20052. Franceschi, Vincent R. and Harry T. Horner Jr., "Calcium oxalate crystals in plants", THE BOTANICAL REVIEW, vol. 46, No. 4, Oct-Dec 1980, pp. 361-427.
3. Piperno, Dolores R., PHYTOLITHS, AltaMira Press, 2006.
4. Rapp, George Jr. and Susan C. Mulholland (eds), PHYTOLITH SYSTEMATICS, Plenum Press, 1992.
5. Madella, M., A. Alexandre, and T Ball, "International Code for Phytolith nomenclature 1.0", ANNALS OF BOTANY, 2005,available on line at http://aob.oxfordjournals.org/cgi/reprint/mci172v1
6. http://en.wikipedia.org/wiki/Phytoliths
