Tetragonal crystal system |
Bipyramidal simple |
Crystals characterized by the direct union of two pyramids [1616 Chvátal M. Cristalografia: Mineralogia para principiantes [Crystallography: Mineralogy for beginners]. 1st ed. Rio de Janeiro: Sociedade Brasileira de Geologia; 2007. 232 p., 1717 Uloth MB, Clode PL, You MP, Barbetti MJ. Calcium oxalate crystals: An integral component of the Sclerotinia sclerotiorum/ Brassia carinata Pathosystem. PLoS One. 2015;10(3):1-15.]. |
Stem |
Bipyramidal rectangular |
Crystals with a considerably thick, rectangle base, which connects the two pyramids at the ends [1717 Uloth MB, Clode PL, You MP, Barbetti MJ. Calcium oxalate crystals: An integral component of the Sclerotinia sclerotiorum/ Brassia carinata Pathosystem. PLoS One. 2015;10(3):1-15., 1818 Sun XY, Ouyang JM, Zhu WY, Li YB, Gan QZ. Size-dependent toxicity and interactions of calcium oxalate dihydrate crystals on vero renal epithelias cells. J. Mater. Chem. B. 2015;3(1):1864-78.]. |
Stem |
Pyramidal rectangular |
They are presented as a pyramid with a rectangle-shaped base [1616 Chvátal M. Cristalografia: Mineralogia para principiantes [Crystallography: Mineralogy for beginners]. 1st ed. Rio de Janeiro: Sociedade Brasileira de Geologia; 2007. 232 p.]. |
Stem |
Cuneiform |
Crystals resembling a rectangular prism with tapered ends. They got this term because they resemble a wedge [1313 Machado CD, Raman V, Rehman JU. Maia, B. H.; Meneghetti, E. K. Schinus molle: anatomy of leaves and stems, chemical composition and insecticidal activities of volatile oil against bed bug (Cimex lectularius). Rev. Bras. Farmacogn. 2019;29(1):1-10.]. |
Stem |
Druse |
Spherical aggregate of crystals, individually deposited, which can take different shapes (Rhomboidal, styloid) [1919 Franceschi VR, Horner HT. Calcium oxalate crystals in plants. Bot. Rev. 1980;46(4):361-16., 2020 He H, Bleby TM, Vaneklaas EJ, Lambers H, Kuo J. Morphologies and elemental compositions of calcium crystal in phyllodes and branchlets of Acacia robeorum (Leguminosae: Mimosideae). Ann. Bot. 2012;109(5):887-96.]. |
Stem, epidermis and apical cells of the glandular trichome |
Monoclinic crystal system |
Styloid |
They appear as elongated crystals, with pointed ends in frontal view, or truncated on the lateral face [1919 Franceschi VR, Horner HT. Calcium oxalate crystals in plants. Bot. Rev. 1980;46(4):361-16., 2121 Raman V, Horner HT, Khan IA. New and unusual forms of calcium oxalate raphide crystals in the plant kingdom. J. Plant Res. 2014;127(6):721-30.]. |
Stem, epidermis |
Rhomboidal |
Parallelogram with unequal adjacent sides [1313 Machado CD, Raman V, Rehman JU. Maia, B. H.; Meneghetti, E. K. Schinus molle: anatomy of leaves and stems, chemical composition and insecticidal activities of volatile oil against bed bug (Cimex lectularius). Rev. Bras. Farmacogn. 2019;29(1):1-10.]. |
Stem |
Arrow shaped |
It is characterized by having a pointed end and the opposite end with a "V" shaped indentation, resembling the tip of an arrow [2222 Raeski PA, Heiden G, Novatski A, Raman V, Khan IA, Manfron J. Calcium oxalate crystal macropattern and its usefulness in the taxonomy of Baccharis (Asteraceae). Microsc. Res. Tech. 2023;86(7):862-81.]. |
Stem |
Crystalline sand rounded |
Portrayed as a mass of small individual crystals, smaller than 3 µm. They can be of various shapes, as shown here: rounded, styloid and bow-tie-shaped [1919 Franceschi VR, Horner HT. Calcium oxalate crystals in plants. Bot. Rev. 1980;46(4):361-16.]. |
Stem |
Crystalline sand styloid |
Crystalline sand bow-tie-shaped |