Crystal sand

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Crystalline deposits of calcium oxalate are referred to as crystal sand , which are found in 36 families of the Bedecktsamer , mainly in foxtail , red and nightshade plants.

description

Crystal sand consists of 1 to 3 µm - in some cases up to 40 µm - large crystals. They are shaped like a tetrahedron .

Crystal sand is mostly found in the vacuoles of the cells near the vascular bundles of plants with diffuse vascular parenchyma . More rarely, crystals have also been found outside of plant cells, for example in the basic tissue of hemlocks ( tsuga ).

The importance of calcium oxalate crystals for plant growth is almost unclear. Most likely, the meaning will vary from case to case. Possible theories say, among other things, that the crystals represent a form of intermediate storage for calcium and oxalic acid or that they serve as a simple storage possibility for substances that act as cell toxins in other forms. In some aquatic plants, they could be used to aid in the formation of air spaces. Furthermore, crystal sand could have been developed in some plants as a protective mechanism against predators . The deposits of some arum plants (Araceae), especially tannia ( Xanthosoma sagittifolium ), are said to leave an unpleasant feeling in the mouth and throat when eaten .

exploration

Crystal sand was detected by Antoni van Leeuwenhoek as early as the 17th century ; the first microscopic observations were made in 1891. The crystals were found in the plants Solandra grandiflora , Solandra guttata , Solanum auriculatum , Datura arborea and Iochroma tubulosum . Current investigations are mainly carried out by light microscopy , polarization microscopy and, more recently, by crystal structure analysis and scanning electron microscopy .

literature

  • AM Cody and HT Horner: Analytical Resolution of the Crystalline Sand Pyramids. In: American Journal of Botany , Volume 72, Number 7, July 1985. Pages 1149-1158. doi : 10.2307 / 2443462
  • H. v. Philipsborn: About calcium oxalate in plant cells. In: Protoplasma , Volume 41, Number 4, December 1952. Pages 184-187. doi : 10.1007 / BF01254752
  • Christina J. Prychid and Paula J. Rudall: Calcium Oxalate Crystals in Monocotyledons: A Review of their Structure and Systematics. In: Annals of Botany , Volume 84, 1999. Pages 725-739. doi : 10.1006 / anbo.1999.0975

further reading